fix videos not autoplaying when using control arrows in android

Update `display` config to support `!important` flag.

.codespellrc

@@ -0,0 +1,8 @@
+[codespell]
+# Ref: https://github.com/codespell-project/codespell#using-a-config-file
+skip = .git*,package-lock.json,*.css,.codespellrc
+check-hidden = true
+# Ignore super long lines -- must be minimized etc, acronyms
+# and some near hit variables
+ignore-regex = ^.{120,}|\b(currentY|FOM)\b
+# ignore-words-list =

.github/workflows/spellcheck.yml

@@ -0,0 +1,23 @@
+# Codespell configuration is within .codespellrc
+---
+name: Spellcheck
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+
+permissions:
+  contents: read
+
+jobs:
+  codespell:
+    name: Check for spelling errors
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Codespell
+        uses: codespell-project/actions-codespell@v2

.github/workflows/test.yml

@@ -1,4 +1,4 @@
-name: tests
+name: Tests
 
 on:
   - push

README.md

@@ -4,7 +4,7 @@
   </a>
   <br><br>
   <a href="https://github.com/hakimel/reveal.js/actions"><img src="https://github.com/hakimel/reveal.js/workflows/tests/badge.svg"></a>
-  <a href="https://slides.com/"><img src="https://s3.amazonaws.com/static.slid.es/images/slides-github-banner-320x40.png?1" alt="Slides" width="160" height="20"></a>
+  <a href="https://slides.com/"><img src="https://static.slid.es/images/slides-github-banner-320x40.png?1" alt="Slides" width="160" height="20"></a>
 </p>
 
 reveal.js is an open source HTML presentation framework. It enables anyone with a web browser to create beautiful presentations for free. Check out the live demo at [revealjs.com](https://revealjs.com/).
@@ -17,26 +17,6 @@ Want to create reveal.js presentation in a graphical editor? Try <https://slides
 
 ---
 
-### Sponsors
-Hakim's open source work is supported by <a href="https://github.com/sponsors/hakimel">GitHub sponsors</a>. Special thanks to:
-<div align="center">
-  <table>
-    <td align="center">
-      <a href="https://workos.com/?utm_campaign=github_repo&utm_medium=referral&utm_content=revealjs&utm_source=github">
-        <div>
-          <img src="https://user-images.githubusercontent.com/629429/151508669-efb4c3b3-8fe3-45eb-8e47-e9510b5f0af1.svg" width="290" alt="WorkOS">
-        </div>
-        <b>Your app, enterprise-ready.</b>
-        <div>
-          <sub>Start selling to enterprise customers with just a few lines of code. Add Single Sign-On (and more) in minutes instead of months.</sup>
-        </div>
-      </a>
-    </td>
-  </table>
-</div>
-
----
-
 ### Getting started
 - 🚀 [Install reveal.js](https://revealjs.com/installation)
 - 👀 [View the demo presentation](https://revealjs.com/demo)

css/layout.scss

@@ -25,6 +25,7 @@
 // Stack multiple elements on top of each other
 .reveal .r-stack {
 	display: grid;
+	grid-template-rows: 100%;
 }
 
 .reveal .r-stack > * {

css/reveal.scss

@@ -1,5 +1,3 @@
-@use "sass:math";
-
 /**
  * reveal.js
  * http://revealjs.com
@@ -8,6 +6,7 @@
  * Copyright (C) Hakim El Hattab, https://hakim.se
  */
 
+@use "sass:math";
 @import 'layout';
 
 /*********************************************
@@ -19,7 +18,7 @@ html.reveal-full-page {
 	height: 100%;
 	height: 100vh;
 	height: calc( var(--vh, 1vh) * 100 );
-	height: 100svh;
+	height: 100dvh;
 	overflow: hidden;
 }
 
@@ -34,6 +33,16 @@ html.reveal-full-page {
 	color: #000;
 
 	--r-controls-spacing: 12px;
+	--r-overlay-header-height: 40px;
+	--r-overlay-margin: 0px;
+	--r-overlay-padding: 6px;
+	--r-overlay-gap: 5px;
+}
+
+@media screen and (max-width: 1024px), (max-height: 768px) {
+	.reveal-viewport {
+		--r-overlay-header-height: 26px;
+	}
 }
 
 // Force the presentation to cover the full viewport when we
@@ -631,11 +640,16 @@ $controlsArrowAngleActive: 36deg;
 	touch-action: pinch-zoom;
 }
 
-// Swiping on an embedded deck should not block page scrolling
+// Swiping on an embedded deck should not block page scrolling...
 .reveal.embedded {
 	touch-action: pan-y;
 }
 
+// ... unless we're on a vertical slide
+.reveal.embedded.is-vertical-slide {
+	touch-action: none;
+}
+
 .reveal .slides {
 	position: absolute;
 	width: 100%;
@@ -995,7 +1009,7 @@ $controlsArrowAngleActive: 36deg;
 		border-radius: 4px;
 		box-shadow: 0px 95px 25px rgba(0,0,0,0.2);
 
-		-webkit-transform: translateZ(-90px) rotateX( 65deg );
+		transform: translateZ(-90px) rotateX( 65deg );
 	}
 
 .reveal.page .slides>section.stack {
@@ -1314,12 +1328,6 @@ $controlsArrowAngleActive: 36deg;
 	perspective-origin: 50% 50%;
 	perspective: 700px;
 
-	.slides {
-		// Fixes overview rendering errors in FF48+, not applied to
-		// other browsers since it degrades performance
-		-moz-transform-style: preserve-3d;
-	}
-
 	.slides section {
 		height: 100%;
 		top: 0 !important;
@@ -1331,9 +1339,12 @@ $controlsArrowAngleActive: 36deg;
 	}
 	.slides section:hover,
 	.slides section.present {
-		outline: 10px solid rgba(150,150,150,0.4);
+		outline: 10px solid rgba(150,150,150,0.6);
 		outline-offset: 10px;
 	}
+	.slides section.present {
+		outline: 10px solid var(--r-link-color);
+	}
 	.slides section .fragment {
 		opacity: 1;
 		transition: none;
@@ -1352,10 +1363,6 @@ $controlsArrowAngleActive: 36deg;
 
 	.backgrounds {
 		perspective: inherit;
-
-		// Fixes overview rendering errors in FF48+, not applied to
-		// other browsers since it degrades performance
-		-moz-transform-style: preserve-3d;
 	}
 
 	.backgrounds .slide-background {
@@ -1435,160 +1442,234 @@ $controlsArrowAngleActive: 36deg;
  * OVERLAY FOR LINK PREVIEWS AND HELP
  *********************************************/
 
-$overlayHeaderHeight: 40px;
-$overlayHeaderPadding: 5px;
+@keyframes fade-in {
+	from { opacity: 0; }
+	to { opacity: 1; }
+}
 
-.reveal > .overlay {
+@keyframes scale-up {
+	from { transform: scale( 0.95 ); }
+	to { transform: scale( 1 ); }
+}
+
+.reveal [data-preview-image],
+.reveal [data-preview-video],
+.reveal [data-preview-link]:not(a):not([data-preview-link=false]) {
+	cursor: zoom-in;
+}
+
+.r-overlay {
 	position: absolute;
-	top: 0;
-	left: 0;
+	top: var(--r-overlay-margin);
+	right: var(--r-overlay-margin);
+	bottom: var(--r-overlay-margin);
+	left: var(--r-overlay-margin);
+	border-radius: min( var(--r-overlay-margin), 6px );
+	z-index: 99;
+	background: rgba( 0, 0, 0, 0.95 );
+	backdrop-filter: blur( 10px );
+	transition: all 0.3s ease;
+	color: #fff;
+	animation: fade-in 0.3s ease;
+	font-family: ui-sans-serif, system-ui, -apple-system, Helvetica, sans-serif;
+}
+
+.r-overlay-viewport {
+	position: absolute;
+	top: var(--r-overlay-padding);
+	right: var(--r-overlay-padding);
+	bottom: var(--r-overlay-padding);
+	left: var(--r-overlay-padding);
+	gap: var(--r-overlay-gap);
+	display: flex;
+	flex-direction: column;
+}
+
+.r-overlay-header {
+	display: flex;
+	z-index: 2;
+	box-sizing: border-box;
+	align-items: center;
+	justify-content: flex-end;
+	height: var(--r-overlay-header-height);
+	gap: 6px;
+}
+.r-overlay-header .r-overlay-button {
+	all: unset;
+	display: flex;
+	align-items: center;
+	justify-content: center;
+	min-width: var(--r-overlay-header-height);
+	min-height: var(--r-overlay-header-height);
+	padding: 0 calc(var(--r-overlay-header-height) / 4);
+	opacity: 1;
+	border-radius: 6px;
+	font-size: 18px;
+	gap: 8px;
+	cursor: pointer;
+
+	box-sizing: border-box;
+}
+.r-overlay-header .r-overlay-button:hover {
+	opacity: 1;
+	background-color: rgba( 255, 255, 255, 0.15 );
+}
+.r-overlay-header .icon {
+	display: inline-block;
+	width: 20px;
+	height: 20px;
+
+	background-position: 50% 50%;
+	background-size: 100%;
+	background-repeat: no-repeat;
+}
+.r-overlay-close .icon {
+	background-image: url(data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSIxNSIgaGVpZ2h0PSIxNSIgZmlsbD0ibm9uZSI+PHBhdGggZmlsbD0iI2ZmZiIgZmlsbC1ydWxlPSJldmVub2RkIiBkPSJNMTIuODU0IDIuODU0YS41LjUgMCAwIDAtLjcwOC0uNzA4TDcuNSA2Ljc5MyAyLjg1NCAyLjE0NmEuNS41IDAgMSAwLS43MDguNzA4TDYuNzkzIDcuNWwtNC42NDcgNC42NDZhLjUuNSAwIDAgMCAuNzA4LjcwOEw3LjUgOC4yMDdsNC42NDYgNC42NDdhLjUuNSAwIDAgMCAuNzA4LS43MDhMOC4yMDcgNy41bDQuNjQ3LTQuNjQ2WiIgY2xpcC1ydWxlPSJldmVub2RkIi8+PC9zdmc+);
+}
+.r-overlay-external .icon {
+	background-image: url(data:image/svg+xml;base64,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);
+}
+
+.r-overlay-content {
+	position: relative;
+	display: grid;
+	place-items: center;
+	border-radius: 6px;
+	overflow: hidden;
+	flex-grow: 1;
+	background-color: rgba(20, 20, 20, 0.8);
+	animation: scale-up 0.5s cubic-bezier(0.260, 0.860, 0.440, 0.985);
+}
+
+.r-overlay-spinner {
+	position: absolute;
+	display: block;
+	top: 50%;
+	left: 50%;
+	width: 32px;
+	height: 32px;
+	margin: -16px 0 0 -16px;
+	z-index: 10;
+	background-image: url(data:image/gif;base64,R0lGODlhIAAgAPMAAJmZmf%2F%2F%2F6%2Bvr8nJybW1tcDAwOjo6Nvb26ioqKOjo7Ozs%2FLy8vz8%2FAAAAAAAAAAAACH%2FC05FVFNDQVBFMi4wAwEAAAAh%2FhpDcmVhdGVkIHdpdGggYWpheGxvYWQuaW5mbwAh%2BQQJCgAAACwAAAAAIAAgAAAE5xDISWlhperN52JLhSSdRgwVo1ICQZRUsiwHpTJT4iowNS8vyW2icCF6k8HMMBkCEDskxTBDAZwuAkkqIfxIQyhBQBFvAQSDITM5VDW6XNE4KagNh6Bgwe60smQUB3d4Rz1ZBApnFASDd0hihh12BkE9kjAJVlycXIg7CQIFA6SlnJ87paqbSKiKoqusnbMdmDC2tXQlkUhziYtyWTxIfy6BE8WJt5YJvpJivxNaGmLHT0VnOgSYf0dZXS7APdpB309RnHOG5gDqXGLDaC457D1zZ%2FV%2FnmOM82XiHRLYKhKP1oZmADdEAAAh%2BQQJCgAAACwAAAAAIAAgAAAE6hDISWlZpOrNp1lGNRSdRpDUolIGw5RUYhhHukqFu8DsrEyqnWThGvAmhVlteBvojpTDDBUEIFwMFBRAmBkSgOrBFZogCASwBDEY%2FCZSg7GSE0gSCjQBMVG023xWBhklAnoEdhQEfyNqMIcKjhRsjEdnezB%2BA4k8gTwJhFuiW4dokXiloUepBAp5qaKpp6%2BHo7aWW54wl7obvEe0kRuoplCGepwSx2jJvqHEmGt6whJpGpfJCHmOoNHKaHx61WiSR92E4lbFoq%2BB6QDtuetcaBPnW6%2BO7wDHpIiK9SaVK5GgV543tzjgGcghAgAh%2BQQJCgAAACwAAAAAIAAgAAAE7hDISSkxpOrN5zFHNWRdhSiVoVLHspRUMoyUakyEe8PTPCATW9A14E0UvuAKMNAZKYUZCiBMuBakSQKG8G2FzUWox2AUtAQFcBKlVQoLgQReZhQlCIJesQXI5B0CBnUMOxMCenoCfTCEWBsJColTMANldx15BGs8B5wlCZ9Po6OJkwmRpnqkqnuSrayqfKmqpLajoiW5HJq7FL1Gr2mMMcKUMIiJgIemy7xZtJsTmsM4xHiKv5KMCXqfyUCJEonXPN2rAOIAmsfB3uPoAK%2B%2BG%2Bw48edZPK%2BM6hLJpQg484enXIdQFSS1u6UhksENEQAAIfkECQoAAAAsAAAAACAAIAAABOcQyEmpGKLqzWcZRVUQnZYg1aBSh2GUVEIQ2aQOE%2BG%2BcD4ntpWkZQj1JIiZIogDFFyHI0UxQwFugMSOFIPJftfVAEoZLBbcLEFhlQiqGp1Vd140AUklUN3eCA51C1EWMzMCezCBBmkxVIVHBWd3HHl9JQOIJSdSnJ0TDKChCwUJjoWMPaGqDKannasMo6WnM562R5YluZRwur0wpgqZE7NKUm%2BFNRPIhjBJxKZteWuIBMN4zRMIVIhffcgojwCF117i4nlLnY5ztRLsnOk%2BaV%2BoJY7V7m76PdkS4trKcdg0Zc0tTcKkRAAAIfkECQoAAAAsAAAAACAAIAAABO4QyEkpKqjqzScpRaVkXZWQEximw1BSCUEIlDohrft6cpKCk5xid5MNJTaAIkekKGQkWyKHkvhKsR7ARmitkAYDYRIbUQRQjWBwJRzChi9CRlBcY1UN4g0%2FVNB0AlcvcAYHRyZPdEQFYV8ccwR5HWxEJ02YmRMLnJ1xCYp0Y5idpQuhopmmC2KgojKasUQDk5BNAwwMOh2RtRq5uQuPZKGIJQIGwAwGf6I0JXMpC8C7kXWDBINFMxS4DKMAWVWAGYsAdNqW5uaRxkSKJOZKaU3tPOBZ4DuK2LATgJhkPJMgTwKCdFjyPHEnKxFCDhEAACH5BAkKAAAALAAAAAAgACAAAATzEMhJaVKp6s2nIkolIJ2WkBShpkVRWqqQrhLSEu9MZJKK9y1ZrqYK9WiClmvoUaF8gIQSNeF1Er4MNFn4SRSDARWroAIETg1iVwuHjYB1kYc1mwruwXKC9gmsJXliGxc%2BXiUCby9ydh1sOSdMkpMTBpaXBzsfhoc5l58Gm5yToAaZhaOUqjkDgCWNHAULCwOLaTmzswadEqggQwgHuQsHIoZCHQMMQgQGubVEcxOPFAcMDAYUA85eWARmfSRQCdcMe0zeP1AAygwLlJtPNAAL19DARdPzBOWSm1brJBi45soRAWQAAkrQIykShQ9wVhHCwCQCACH5BAkKAAAALAAAAAAgACAAAATrEMhJaVKp6s2nIkqFZF2VIBWhUsJaTokqUCoBq%2BE71SRQeyqUToLA7VxF0JDyIQh%2FMVVPMt1ECZlfcjZJ9mIKoaTl1MRIl5o4CUKXOwmyrCInCKqcWtvadL2SYhyASyNDJ0uIiRMDjI0Fd30%2FiI2UA5GSS5UDj2l6NoqgOgN4gksEBgYFf0FDqKgHnyZ9OX8HrgYHdHpcHQULXAS2qKpENRg7eAMLC7kTBaixUYFkKAzWAAnLC7FLVxLWDBLKCwaKTULgEwbLA4hJtOkSBNqITT3xEgfLpBtzE%2FjiuL04RGEBgwWhShRgQExHBAAh%2BQQJCgAAACwAAAAAIAAgAAAE7xDISWlSqerNpyJKhWRdlSAVoVLCWk6JKlAqAavhO9UkUHsqlE6CwO1cRdCQ8iEIfzFVTzLdRAmZX3I2SfZiCqGk5dTESJeaOAlClzsJsqwiJwiqnFrb2nS9kmIcgEsjQydLiIlHehhpejaIjzh9eomSjZR%2BipslWIRLAgMDOR2DOqKogTB9pCUJBagDBXR6XB0EBkIIsaRsGGMMAxoDBgYHTKJiUYEGDAzHC9EACcUGkIgFzgwZ0QsSBcXHiQvOwgDdEwfFs0sDzt4S6BK4xYjkDOzn0unFeBzOBijIm1Dgmg5YFQwsCMjp1oJ8LyIAACH5BAkKAAAALAAAAAAgACAAAATwEMhJaVKp6s2nIkqFZF2VIBWhUsJaTokqUCoBq%2BE71SRQeyqUToLA7VxF0JDyIQh%2FMVVPMt1ECZlfcjZJ9mIKoaTl1MRIl5o4CUKXOwmyrCInCKqcWtvadL2SYhyASyNDJ0uIiUd6GGl6NoiPOH16iZKNlH6KmyWFOggHhEEvAwwMA0N9GBsEC6amhnVcEwavDAazGwIDaH1ipaYLBUTCGgQDA8NdHz0FpqgTBwsLqAbWAAnIA4FWKdMLGdYGEgraigbT0OITBcg5QwPT4xLrROZL6AuQAPUS7bxLpoWidY0JtxLHKhwwMJBTHgPKdEQAACH5BAkKAAAALAAAAAAgACAAAATrEMhJaVKp6s2nIkqFZF2VIBWhUsJaTokqUCoBq%2BE71SRQeyqUToLA7VxF0JDyIQh%2FMVVPMt1ECZlfcjZJ9mIKoaTl1MRIl5o4CUKXOwmyrCInCKqcWtvadL2SYhyASyNDJ0uIiUd6GAULDJCRiXo1CpGXDJOUjY%2BYip9DhToJA4RBLwMLCwVDfRgbBAaqqoZ1XBMHswsHtxtFaH1iqaoGNgAIxRpbFAgfPQSqpbgGBqUD1wBXeCYp1AYZ19JJOYgH1KwA4UBvQwXUBxPqVD9L3sbp2BNk2xvvFPJd%2BMFCN6HAAIKgNggY0KtEBAAh%2BQQJCgAAACwAAAAAIAAgAAAE6BDISWlSqerNpyJKhWRdlSAVoVLCWk6JKlAqAavhO9UkUHsqlE6CwO1cRdCQ8iEIfzFVTzLdRAmZX3I2SfYIDMaAFdTESJeaEDAIMxYFqrOUaNW4E4ObYcCXaiBVEgULe0NJaxxtYksjh2NLkZISgDgJhHthkpU4mW6blRiYmZOlh4JWkDqILwUGBnE6TYEbCgevr0N1gH4At7gHiRpFaLNrrq8HNgAJA70AWxQIH1%2BvsYMDAzZQPC9VCNkDWUhGkuE5PxJNwiUK4UfLzOlD4WvzAHaoG9nxPi5d%2BjYUqfAhhykOFwJWiAAAIfkECQoAAAAsAAAAACAAIAAABPAQyElpUqnqzaciSoVkXVUMFaFSwlpOCcMYlErAavhOMnNLNo8KsZsMZItJEIDIFSkLGQoQTNhIsFehRww2CQLKF0tYGKYSg%2BygsZIuNqJksKgbfgIGepNo2cIUB3V1B3IvNiBYNQaDSTtfhhx0CwVPI0UJe0%2Bbm4g5VgcGoqOcnjmjqDSdnhgEoamcsZuXO1aWQy8KAwOAuTYYGwi7w5h%2BKr0SJ8MFihpNbx%2B4Erq7BYBuzsdiH1jCAzoSfl0rVirNbRXlBBlLX%2BBP0XJLAPGzTkAuAOqb0WT5AH7OcdCm5B8TgRwSRKIHQtaLCwg1RAAAOwAAAAAAAAAAAA%3D%3D);
+
+	visibility: hidden;
+	opacity: 0;
+}
+
+// Preview overlay
+.r-overlay-preview .r-overlay-content iframe {
 	width: 100%;
 	height: 100%;
-	z-index: 1000;
-	background: rgba( 0, 0, 0, 0.95 );
-	backdrop-filter: blur( 6px );
+	max-width: 100%;
+	max-height: 100%;
+	border: 0;
+
+	opacity: 0;
+	visibility: hidden;
 	transition: all 0.3s ease;
 }
 
-	.reveal > .overlay .spinner {
-		position: absolute;
-		display: block;
-		top: 50%;
-		left: 50%;
-		width: 32px;
-		height: 32px;
-		margin: -16px 0 0 -16px;
-		z-index: 10;
-		background-image: url(data:image/gif;base64,R0lGODlhIAAgAPMAAJmZmf%2F%2F%2F6%2Bvr8nJybW1tcDAwOjo6Nvb26ioqKOjo7Ozs%2FLy8vz8%2FAAAAAAAAAAAACH%2FC05FVFNDQVBFMi4wAwEAAAAh%2FhpDcmVhdGVkIHdpdGggYWpheGxvYWQuaW5mbwAh%2BQQJCgAAACwAAAAAIAAgAAAE5xDISWlhperN52JLhSSdRgwVo1ICQZRUsiwHpTJT4iowNS8vyW2icCF6k8HMMBkCEDskxTBDAZwuAkkqIfxIQyhBQBFvAQSDITM5VDW6XNE4KagNh6Bgwe60smQUB3d4Rz1ZBApnFASDd0hihh12BkE9kjAJVlycXIg7CQIFA6SlnJ87paqbSKiKoqusnbMdmDC2tXQlkUhziYtyWTxIfy6BE8WJt5YJvpJivxNaGmLHT0VnOgSYf0dZXS7APdpB309RnHOG5gDqXGLDaC457D1zZ%2FV%2FnmOM82XiHRLYKhKP1oZmADdEAAAh%2BQQJCgAAACwAAAAAIAAgAAAE6hDISWlZpOrNp1lGNRSdRpDUolIGw5RUYhhHukqFu8DsrEyqnWThGvAmhVlteBvojpTDDBUEIFwMFBRAmBkSgOrBFZogCASwBDEY%2FCZSg7GSE0gSCjQBMVG023xWBhklAnoEdhQEfyNqMIcKjhRsjEdnezB%2BA4k8gTwJhFuiW4dokXiloUepBAp5qaKpp6%2BHo7aWW54wl7obvEe0kRuoplCGepwSx2jJvqHEmGt6whJpGpfJCHmOoNHKaHx61WiSR92E4lbFoq%2BB6QDtuetcaBPnW6%2BO7wDHpIiK9SaVK5GgV543tzjgGcghAgAh%2BQQJCgAAACwAAAAAIAAgAAAE7hDISSkxpOrN5zFHNWRdhSiVoVLHspRUMoyUakyEe8PTPCATW9A14E0UvuAKMNAZKYUZCiBMuBakSQKG8G2FzUWox2AUtAQFcBKlVQoLgQReZhQlCIJesQXI5B0CBnUMOxMCenoCfTCEWBsJColTMANldx15BGs8B5wlCZ9Po6OJkwmRpnqkqnuSrayqfKmqpLajoiW5HJq7FL1Gr2mMMcKUMIiJgIemy7xZtJsTmsM4xHiKv5KMCXqfyUCJEonXPN2rAOIAmsfB3uPoAK%2B%2BG%2Bw48edZPK%2BM6hLJpQg484enXIdQFSS1u6UhksENEQAAIfkECQoAAAAsAAAAACAAIAAABOcQyEmpGKLqzWcZRVUQnZYg1aBSh2GUVEIQ2aQOE%2BG%2BcD4ntpWkZQj1JIiZIogDFFyHI0UxQwFugMSOFIPJftfVAEoZLBbcLEFhlQiqGp1Vd140AUklUN3eCA51C1EWMzMCezCBBmkxVIVHBWd3HHl9JQOIJSdSnJ0TDKChCwUJjoWMPaGqDKannasMo6WnM562R5YluZRwur0wpgqZE7NKUm%2BFNRPIhjBJxKZteWuIBMN4zRMIVIhffcgojwCF117i4nlLnY5ztRLsnOk%2BaV%2BoJY7V7m76PdkS4trKcdg0Zc0tTcKkRAAAIfkECQoAAAAsAAAAACAAIAAABO4QyEkpKqjqzScpRaVkXZWQEximw1BSCUEIlDohrft6cpKCk5xid5MNJTaAIkekKGQkWyKHkvhKsR7ARmitkAYDYRIbUQRQjWBwJRzChi9CRlBcY1UN4g0%2FVNB0AlcvcAYHRyZPdEQFYV8ccwR5HWxEJ02YmRMLnJ1xCYp0Y5idpQuhopmmC2KgojKasUQDk5BNAwwMOh2RtRq5uQuPZKGIJQIGwAwGf6I0JXMpC8C7kXWDBINFMxS4DKMAWVWAGYsAdNqW5uaRxkSKJOZKaU3tPOBZ4DuK2LATgJhkPJMgTwKCdFjyPHEnKxFCDhEAACH5BAkKAAAALAAAAAAgACAAAATzEMhJaVKp6s2nIkolIJ2WkBShpkVRWqqQrhLSEu9MZJKK9y1ZrqYK9WiClmvoUaF8gIQSNeF1Er4MNFn4SRSDARWroAIETg1iVwuHjYB1kYc1mwruwXKC9gmsJXliGxc%2BXiUCby9ydh1sOSdMkpMTBpaXBzsfhoc5l58Gm5yToAaZhaOUqjkDgCWNHAULCwOLaTmzswadEqggQwgHuQsHIoZCHQMMQgQGubVEcxOPFAcMDAYUA85eWARmfSRQCdcMe0zeP1AAygwLlJtPNAAL19DARdPzBOWSm1brJBi45soRAWQAAkrQIykShQ9wVhHCwCQCACH5BAkKAAAALAAAAAAgACAAAATrEMhJaVKp6s2nIkqFZF2VIBWhUsJaTokqUCoBq%2BE71SRQeyqUToLA7VxF0JDyIQh%2FMVVPMt1ECZlfcjZJ9mIKoaTl1MRIl5o4CUKXOwmyrCInCKqcWtvadL2SYhyASyNDJ0uIiRMDjI0Fd30%2FiI2UA5GSS5UDj2l6NoqgOgN4gksEBgYFf0FDqKgHnyZ9OX8HrgYHdHpcHQULXAS2qKpENRg7eAMLC7kTBaixUYFkKAzWAAnLC7FLVxLWDBLKCwaKTULgEwbLA4hJtOkSBNqITT3xEgfLpBtzE%2FjiuL04RGEBgwWhShRgQExHBAAh%2BQQJCgAAACwAAAAAIAAgAAAE7xDISWlSqerNpyJKhWRdlSAVoVLCWk6JKlAqAavhO9UkUHsqlE6CwO1cRdCQ8iEIfzFVTzLdRAmZX3I2SfZiCqGk5dTESJeaOAlClzsJsqwiJwiqnFrb2nS9kmIcgEsjQydLiIlHehhpejaIjzh9eomSjZR%2BipslWIRLAgMDOR2DOqKogTB9pCUJBagDBXR6XB0EBkIIsaRsGGMMAxoDBgYHTKJiUYEGDAzHC9EACcUGkIgFzgwZ0QsSBcXHiQvOwgDdEwfFs0sDzt4S6BK4xYjkDOzn0unFeBzOBijIm1Dgmg5YFQwsCMjp1oJ8LyIAACH5BAkKAAAALAAAAAAgACAAAATwEMhJaVKp6s2nIkqFZF2VIBWhUsJaTokqUCoBq%2BE71SRQeyqUToLA7VxF0JDyIQh%2FMVVPMt1ECZlfcjZJ9mIKoaTl1MRIl5o4CUKXOwmyrCInCKqcWtvadL2SYhyASyNDJ0uIiUd6GGl6NoiPOH16iZKNlH6KmyWFOggHhEEvAwwMA0N9GBsEC6amhnVcEwavDAazGwIDaH1ipaYLBUTCGgQDA8NdHz0FpqgTBwsLqAbWAAnIA4FWKdMLGdYGEgraigbT0OITBcg5QwPT4xLrROZL6AuQAPUS7bxLpoWidY0JtxLHKhwwMJBTHgPKdEQAACH5BAkKAAAALAAAAAAgACAAAATrEMhJaVKp6s2nIkqFZF2VIBWhUsJaTokqUCoBq%2BE71SRQeyqUToLA7VxF0JDyIQh%2FMVVPMt1ECZlfcjZJ9mIKoaTl1MRIl5o4CUKXOwmyrCInCKqcWtvadL2SYhyASyNDJ0uIiUd6GAULDJCRiXo1CpGXDJOUjY%2BYip9DhToJA4RBLwMLCwVDfRgbBAaqqoZ1XBMHswsHtxtFaH1iqaoGNgAIxRpbFAgfPQSqpbgGBqUD1wBXeCYp1AYZ19JJOYgH1KwA4UBvQwXUBxPqVD9L3sbp2BNk2xvvFPJd%2BMFCN6HAAIKgNggY0KtEBAAh%2BQQJCgAAACwAAAAAIAAgAAAE6BDISWlSqerNpyJKhWRdlSAVoVLCWk6JKlAqAavhO9UkUHsqlE6CwO1cRdCQ8iEIfzFVTzLdRAmZX3I2SfYIDMaAFdTESJeaEDAIMxYFqrOUaNW4E4ObYcCXaiBVEgULe0NJaxxtYksjh2NLkZISgDgJhHthkpU4mW6blRiYmZOlh4JWkDqILwUGBnE6TYEbCgevr0N1gH4At7gHiRpFaLNrrq8HNgAJA70AWxQIH1%2BvsYMDAzZQPC9VCNkDWUhGkuE5PxJNwiUK4UfLzOlD4WvzAHaoG9nxPi5d%2BjYUqfAhhykOFwJWiAAAIfkECQoAAAAsAAAAACAAIAAABPAQyElpUqnqzaciSoVkXVUMFaFSwlpOCcMYlErAavhOMnNLNo8KsZsMZItJEIDIFSkLGQoQTNhIsFehRww2CQLKF0tYGKYSg%2BygsZIuNqJksKgbfgIGepNo2cIUB3V1B3IvNiBYNQaDSTtfhhx0CwVPI0UJe0%2Bbm4g5VgcGoqOcnjmjqDSdnhgEoamcsZuXO1aWQy8KAwOAuTYYGwi7w5h%2BKr0SJ8MFihpNbx%2B4Erq7BYBuzsdiH1jCAzoSfl0rVirNbRXlBBlLX%2BBP0XJLAPGzTkAuAOqb0WT5AH7OcdCm5B8TgRwSRKIHQtaLCwg1RAAAOwAAAAAAAAAAAA%3D%3D);
+.r-overlay-preview[data-state="loaded"] iframe {
+	opacity: 1;
+	visibility: visible;
+}
 
-		visibility: visible;
-		opacity: 0.6;
-		transition: all 0.3s ease;
-	}
+.r-overlay-preview .r-overlay-content img,
+.r-overlay-preview .r-overlay-content video {
+	position: absolute;
+	max-width: 100%;
+	max-height: 100%;
+	width: 100%;
+	height: 100%;
+	margin: 0;
+	object-fit: scale-down;
+}
 
-	.reveal > .overlay header {
-		position: absolute;
-		left: 0;
-		top: 0;
-		width: 100%;
-		padding: $overlayHeaderPadding;
-		z-index: 2;
-		box-sizing: border-box;
-	}
-		.reveal > .overlay header a {
-			display: inline-block;
-			width: $overlayHeaderHeight;
-			height: $overlayHeaderHeight;
-			line-height: 36px;
-			padding: 0 10px;
-			float: right;
-			opacity: 0.6;
+.r-overlay-preview[data-preview-fit="none"] img,
+.r-overlay-preview[data-preview-fit="none"] video {
+	object-fit: none;
+}
 
-			box-sizing: border-box;
-		}
-			.reveal > .overlay header a:hover {
-				opacity: 1;
-			}
-			.reveal > .overlay header a .icon {
-				display: inline-block;
-				width: 20px;
-				height: 20px;
+.r-overlay-preview[data-preview-fit="scale-down"] img,
+.r-overlay-preview[data-preview-fit="scale-down"] video {
+	object-fit: scale-down;
+}
 
-				background-position: 50% 50%;
-				background-size: 100%;
-				background-repeat: no-repeat;
-			}
-			.reveal > .overlay header a.close .icon {
-				background-image: url(data:image/png;base64,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);
-			}
-			.reveal > .overlay header a.external .icon {
-				background-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAYAAABzenr0AAAAcElEQVRYR+2WSQoAIQwEzf8f7XiOMkUQxUPlGkM3hVmiQfQR9GYnH1SsAQlI4DiBqkCMoNb9y2e90IAEJPAcgdznU9+engMaeJ7Azh5Y1U67gAho4DqBqmB1buAf0MB1AlVBek83ZPkmJMGc1wAR+AAqod/B97TRpQAAAABJRU5ErkJggg==);
-			}
+.r-overlay-preview[data-preview-fit="contain"] img,
+.r-overlay-preview[data-preview-fit="contain"] video {
+	object-fit: contain;
+}
 
-	.reveal > .overlay .viewport {
-		position: absolute;
-		display: flex;
-		top: $overlayHeaderHeight + $overlayHeaderPadding*2;
-		right: 0;
-		bottom: 0;
-		left: 0;
-	}
+.r-overlay-preview[data-preview-fit="cover"] img,
+.r-overlay-preview[data-preview-fit="cover"] video {
+	object-fit: cover;
+}
 
-	.reveal > .overlay.overlay-preview .viewport iframe {
-		width: 100%;
-		height: 100%;
-		max-width: 100%;
-		max-height: 100%;
-		border: 0;
+.r-overlay-preview[data-state="loaded"] .r-overlay-content-inner  {
+	position: absolute;
+	z-index: -1;
+	left: 0;
+	top: 45%;
+	width: 100%;
+	text-align: center;
+	letter-spacing: normal;
+}
+.r-overlay-preview .r-overlay-error {
+	font-size: 18px;
+	color: orange;
+}
 
-		opacity: 0;
-		visibility: hidden;
-		transition: all 0.3s ease;
-	}
+.r-overlay-preview .x-frame-error  {
+	opacity: 0;
+	transition: opacity 0.3s ease 0.3s;
+}
+.r-overlay-preview[data-state="loaded"] .x-frame-error  {
+	opacity: 1;
+}
 
-	.reveal > .overlay.overlay-preview.loaded .viewport iframe {
-		opacity: 1;
-		visibility: visible;
-	}
+.r-overlay-preview[data-state="loading"] .r-overlay-spinner {
+	opacity: 0.6;
+	visibility: visible;
+}
 
-	.reveal > .overlay.overlay-preview.loaded .viewport-inner  {
-		position: absolute;
-		z-index: -1;
-		left: 0;
-		top: 45%;
-		width: 100%;
-		text-align: center;
-		letter-spacing: normal;
-	}
-	.reveal > .overlay.overlay-preview .x-frame-error  {
-		opacity: 0;
-		transition: opacity 0.3s ease 0.3s;
-	}
-	.reveal > .overlay.overlay-preview.loaded .x-frame-error  {
-		opacity: 1;
-	}
+// Help overlay
+.r-overlay-help .r-overlay-content {
+	overflow: auto;
+}
 
-	.reveal > .overlay.overlay-preview.loaded .spinner {
-		opacity: 0;
-		visibility: hidden;
-		transform: scale(0.2);
-	}
+.r-overlay-help-content {
+	max-width: 560px;
+	padding: 20px 0;
+	margin: auto;
+	text-align: center;
+	letter-spacing: normal;
+}
 
-	.reveal > .overlay.overlay-help .viewport {
-		overflow: auto;
-		color: #fff;
-	}
+.r-overlay-help-content .title {
+	font-size: 20px;
+	margin-top: 0;
+}
 
-	.reveal > .overlay.overlay-help .viewport .viewport-inner {
-		width: 600px;
-		margin: auto;
-		padding: 20px 20px 80px 20px;
-		text-align: center;
-		letter-spacing: normal;
-	}
+/* Specificity battle with reveal.js theme table styles */
+.r-overlay-help .r-overlay-help-content table {
+	border: 1px solid #fff;
+	border-collapse: collapse;
+	font-size: 16px;
+	text-align: left;
+}
 
-	.reveal > .overlay.overlay-help .viewport .viewport-inner .title {
-		font-size: 20px;
-	}
+.r-overlay-help .r-overlay-help-content table th,
+.r-overlay-help .r-overlay-help-content table td {
+	width: 240px;
+	padding: 14px;
+	border: 1px solid #fff;
+	vertical-align: middle;
+}
 
-	.reveal > .overlay.overlay-help .viewport .viewport-inner table {
-		border: 1px solid #fff;
-		border-collapse: collapse;
-		font-size: 16px;
-	}
-
-	.reveal > .overlay.overlay-help .viewport .viewport-inner table th,
-	.reveal > .overlay.overlay-help .viewport .viewport-inner table td {
-		width: 200px;
-		padding: 14px;
-		border: 1px solid #fff;
-		vertical-align: middle;
-	}
-
-	.reveal > .overlay.overlay-help .viewport .viewport-inner table th {
-		padding-top: 20px;
-		padding-bottom: 20px;
-	}
+.r-overlay-help .r-overlay-help-content table th {
+	padding-top: 20px;
+	padding-bottom: 20px;
+}
 
 /*********************************************
  * PLAYBACK COMPONENT
@@ -1901,7 +1982,7 @@ $notesWidthPercent: 25%;
 		display: none !important;
 	}
 
-	.overlay,
+	.r-overlay,
 	.pause-overlay {
 		position: fixed;
 	}

css/theme/source/beige.scss

@@ -6,6 +6,7 @@
 
 
 // Default mixins and settings -----------------
+@use "sass:color";
 @import "../template/mixins";
 @import "../template/settings";
 // ---------------------------------------------
@@ -23,7 +24,7 @@ $headingColor: #333;
 $headingTextShadow: none;
 $backgroundColor: #f7f3de;
 $linkColor: #8b743d;
-$linkColorHover: lighten( $linkColor, 20% );
+$linkColorHover: color.scale( $linkColor, $lightness: 20% );
 $selectionBackgroundColor: rgba(79, 64, 28, 0.99);
 $heading1TextShadow: 0 1px 0 #ccc, 0 2px 0 #c9c9c9, 0 3px 0 #bbb, 0 4px 0 #b9b9b9, 0 5px 0 #aaa, 0 6px 1px rgba(0,0,0,.1), 0 0 5px rgba(0,0,0,.1), 0 1px 3px rgba(0,0,0,.3), 0 3px 5px rgba(0,0,0,.2), 0 5px 10px rgba(0,0,0,.25), 0 20px 20px rgba(0,0,0,.15);
 

css/theme/source/black-contrast.scss

@@ -9,6 +9,7 @@
 
 
 // Default mixins and settings -----------------
+@use "sass:color";
 @import "../template/mixins";
 @import "../template/settings";
 // ---------------------------------------------
@@ -32,8 +33,8 @@ $headingLetterSpacing: normal;
 $headingTextTransform: uppercase;
 $headingFontWeight: 600;
 $linkColor: #42affa;
-$linkColorHover: lighten( $linkColor, 15% );
-$selectionBackgroundColor: lighten( $linkColor, 25% );
+$linkColorHover: color.scale( $linkColor, $lightness: 15% );
+$selectionBackgroundColor: color.scale( $linkColor, $lightness: 25% );
 
 $heading1Size: 2.5em;
 $heading2Size: 1.6em;

css/theme/source/black.scss

@@ -6,6 +6,7 @@
 
 
 // Default mixins and settings -----------------
+@use "sass:color";
 @import "../template/mixins";
 @import "../template/settings";
 // ---------------------------------------------
@@ -29,7 +30,7 @@ $headingLetterSpacing: normal;
 $headingTextTransform: uppercase;
 $headingFontWeight: 600;
 $linkColor: #42affa;
-$linkColorHover: lighten( $linkColor, 15% );
+$linkColorHover: color.scale( $linkColor, $lightness: 15% );
 $selectionBackgroundColor: rgba( $linkColor, 0.75 );
 
 $heading1Size: 2.5em;

css/theme/source/blood.scss

@@ -10,7 +10,8 @@
  *
  */
 
- // Default mixins and settings -----------------
+// Default mixins and settings -----------------
+@use "sass:color";
 @import "../template/mixins";
 @import "../template/settings";
 // ---------------------------------------------
@@ -40,7 +41,7 @@ $heading1TextShadow: 0 1px 0 #ccc, 0 2px 0 #c9c9c9, 0 3px 0 #bbb, 0 4px 0 #b9b9b
 
 // Links
 $linkColor: $blood;
-$linkColorHover: lighten( $linkColor, 20% );
+$linkColorHover: color.scale( $linkColor, $lightness: 20% );
 
 // Text selection
 $selectionBackgroundColor: $blood;

css/theme/source/dracula.scss

@@ -9,9 +9,10 @@
 @import "../template/settings";
 // ---------------------------------------------
 
-
-
 // Include theme-specific fonts
+@import url(./fonts/league-gothic/league-gothic.css);
+@import url(https://fonts.googleapis.com/css?family=Lato:400,700,400italic,700italic);
+
 $systemFontsSansSerif: -apple-system,
 					   BlinkMacSystemFont,
 					   avenir next,

css/theme/source/moon.scss

@@ -5,6 +5,7 @@
 
 
 // Default mixins and settings -----------------
+@use "sass:color";
 @import "../template/mixins";
 @import "../template/settings";
 // ---------------------------------------------
@@ -43,7 +44,7 @@ $headingColor: $base2;
 $headingTextShadow: none;
 $backgroundColor: $base03;
 $linkColor: $blue;
-$linkColorHover: lighten( $linkColor, 20% );
+$linkColorHover: color.scale( $linkColor, $lightness: 20% );
 $selectionBackgroundColor: $magenta;
 
 // Change text colors against light slide backgrounds

css/theme/source/night.scss

@@ -6,6 +6,7 @@
 
 
 // Default mixins and settings -----------------
+@use "sass:color";
 @import "../template/mixins";
 @import "../template/settings";
 // ---------------------------------------------
@@ -21,7 +22,7 @@ $backgroundColor: #111;
 
 $mainFont: 'Open Sans', sans-serif;
 $linkColor: #e7ad52;
-$linkColorHover: lighten( $linkColor, 20% );
+$linkColorHover: color.scale( $linkColor, $lightness: 20% );
 $headingFont: 'Montserrat', Impact, sans-serif;
 $headingTextShadow: none;
 $headingLetterSpacing: -0.03em;

css/theme/source/serif.scss

@@ -7,6 +7,7 @@
 
 
 // Default mixins and settings -----------------
+@use "sass:color";
 @import "../template/mixins";
 @import "../template/settings";
 // ---------------------------------------------
@@ -22,7 +23,7 @@ $headingTextShadow: none;
 $headingTextTransform: none;
 $backgroundColor: #F0F1EB;
 $linkColor: #51483D;
-$linkColorHover: lighten( $linkColor, 20% );
+$linkColorHover: color.scale( $linkColor, $lightness: 20% );
 $selectionBackgroundColor: #26351C;
 
 $overlayElementBgColor: 0, 0, 0;

css/theme/source/simple.scss

@@ -8,6 +8,7 @@
 
 
 // Default mixins and settings -----------------
+@use "sass:color";
 @import "../template/mixins";
 @import "../template/settings";
 // ---------------------------------------------
@@ -28,7 +29,7 @@ $headingTextShadow: none;
 $headingTextTransform: none;
 $backgroundColor: #fff;
 $linkColor: #00008B;
-$linkColorHover: lighten( $linkColor, 20% );
+$linkColorHover: color.scale( $linkColor, $lightness: 20% );
 $selectionBackgroundColor: rgba(0, 0, 0, 0.99);
 
 $overlayElementBgColor: 0, 0, 0;

css/theme/source/sky.scss

@@ -6,6 +6,7 @@
 
 
 // Default mixins and settings -----------------
+@use "sass:color";
 @import "../template/mixins";
 @import "../template/settings";
 // ---------------------------------------------
@@ -26,7 +27,7 @@ $headingLetterSpacing: -0.08em;
 $headingTextShadow: none;
 $backgroundColor: #f7fbfc;
 $linkColor: #3b759e;
-$linkColorHover: lighten( $linkColor, 20% );
+$linkColorHover: color.scale( $linkColor, $lightness: 20% );
 $selectionBackgroundColor: #134674;
 
 $overlayElementBgColor: 0, 0, 0;

css/theme/source/solarized.scss

@@ -5,6 +5,7 @@
 
 
 // Default mixins and settings -----------------
+@use "sass:color";
 @import "../template/mixins";
 @import "../template/settings";
 // ---------------------------------------------
@@ -48,7 +49,7 @@ $headingColor: $base01;
 $headingTextShadow: none;
 $backgroundColor: $base3;
 $linkColor: $blue;
-$linkColorHover: lighten( $linkColor, 20% );
+$linkColorHover: color.scale( $linkColor, $lightness: 20% );
 $selectionBackgroundColor: $magenta;
 
 $overlayElementBgColor: 0, 0, 0;

css/theme/source/white-contrast.scss

@@ -9,6 +9,7 @@
 
 
 // Default mixins and settings -----------------
+@use "sass:color";
 @import "../template/mixins";
 @import "../template/settings";
 // ---------------------------------------------
@@ -32,8 +33,8 @@ $headingLetterSpacing: normal;
 $headingTextTransform: uppercase;
 $headingFontWeight: 600;
 $linkColor: #2a76dd;
-$linkColorHover: lighten( $linkColor, 15% );
-$selectionBackgroundColor: lighten( $linkColor, 25% );
+$linkColorHover: color.scale( $linkColor, $lightness: 15% );
+$selectionBackgroundColor: color.scale( $linkColor, $lightness: 25% );
 
 $heading1Size: 2.5em;
 $heading2Size: 1.6em;

css/theme/source/white.scss

@@ -6,6 +6,7 @@
 
 
 // Default mixins and settings -----------------
+@use "sass:color";
 @import "../template/mixins";
 @import "../template/settings";
 // ---------------------------------------------
@@ -29,8 +30,8 @@ $headingLetterSpacing: normal;
 $headingTextTransform: uppercase;
 $headingFontWeight: 600;
 $linkColor: #2a76dd;
-$linkColorHover: lighten( $linkColor, 15% );
-$selectionBackgroundColor: lighten( $linkColor, 25% );
+$linkColorHover: color.scale( $linkColor, $lightness: 15% );
+$selectionBackgroundColor: color.scale( $linkColor, $lightness: 25% );
 
 $heading1Size: 2.5em;
 $heading2Size: 1.6em;

css/theme/template/exposer.scss

@@ -1,4 +1,6 @@
-// Exposes theme's variables for easy re-use in CSS for plugin authors
+// Exposes theme's variables for easy reuse in CSS for plugin authors
+
+@use "sass:color";
 
 :root {
   --r-background-color: #{$backgroundColor};
@@ -21,7 +23,7 @@
   --r-heading4-size: #{$heading4Size};
   --r-code-font: #{$codeFont};
   --r-link-color: #{$linkColor};
-  --r-link-color-dark: #{darken($linkColor , 15% )};
+  --r-link-color-dark: #{color.scale( $linkColor, $lightness: -15% )};
   --r-link-color-hover: #{$linkColorHover};
   --r-selection-background-color: #{$selectionBackgroundColor};
   --r-selection-color: #{$selectionColor};

css/theme/template/settings.scss

@@ -1,3 +1,5 @@
+@use "sass:color";
+
 // Base settings for all themes that can optionally be
 // overridden by the super-theme
 
@@ -32,7 +34,7 @@ $codeFont: monospace;
 
 // Links and actions
 $linkColor: #13DAEC;
-$linkColorHover: lighten( $linkColor, 20% );
+$linkColorHover: color.scale( $linkColor, $lightness: 20% );
 
 // Text selection
 $selectionBackgroundColor: #FF5E99;

css/theme/template/theme.scss

@@ -278,8 +278,7 @@
 
 .reveal .roll span:after {
 	color: #fff;
-	// background: darken( var(--r-link-color), 15% );
-	 background: var(--r-link-color-dark);
+	background: var(--r-link-color-dark);
 
 }
 

demo.html

@@ -165,9 +165,9 @@
 				</section>
 				<section data-auto-animate data-auto-animate-easing="cubic-bezier(0.770, 0.000, 0.175, 1.000)">
 					<div class="r-stack">
-						<div data-id="box1" style="background: cyan; width: 300px; height: 300px; border-radius: 200px;"></div>
-						<div data-id="box2" style="background: magenta; width: 200px; height: 200px; border-radius: 200px;"></div>
-						<div data-id="box3" style="background: yellow; width: 100px; height: 100px; border-radius: 200px;"></div>
+						<div data-id="box1" style="background: cyan; width: 300px; height: 300px;"></div>
+						<div data-id="box2" style="background: magenta; width: 200px; height: 200px;"></div>
+						<div data-id="box3" style="background: yellow; width: 100px; height: 100px;"></div>
 					</div>
 					<h2 style="margin-top: 20px;">Auto-Animate</h2>
 				</section>
@@ -197,6 +197,25 @@
 					</script>
 				</section>
 
+				<section>
+					<h2>Lightbox</h2>
+					Turn any element into a <a href="https://revealjs.com/lightbox/">lightbox</a> using <strong>data‑preview‑image</strong> & <strong>data‑preview‑video</strong>.
+					<div class="r-hstack" style="gap: 2rem;">
+						<div>
+							<pre style="font-size: 12px; width: 100%"><code class="html" data-trim>
+								&lt;img src="image.png" data-preview-image="image.png"&gt;
+							</code></pre>
+							<img src="https://static.slid.es/logo/v2/slides-symbol-1024x1024.png" height="100" data-preview-image>
+						</div>
+						<div>
+							<pre style="font-size: 12px; width: 100%"><code class="html" data-trim>
+								&lt;img src="video.png" data-preview-video="video.mp4"&gt;
+							</code></pre>
+							<img src="https://static.slid.es/site/homepage/v1/homepage-video-editor.png" height="100" data-preview-video="https://static.slid.es/site/homepage/v1/homepage-video-editor.mp4">
+						</div>
+					</div>
+				</section>
+
 				<section>
 					<p>Add the <code>r-fit-text</code> class to auto-size text</p>
 					<h2 class="r-fit-text">FIT TEXT</h2>

dist/theme/beige.css

@@ -33,8 +33,8 @@ section.has-dark-background, section.has-dark-background h1, section.has-dark-ba
   --r-heading4-size: 1em;
   --r-code-font: monospace;
   --r-link-color: #8b743d;
-  --r-link-color-dark: #564826;
-  --r-link-color-hover: #c0a86e;
+  --r-link-color-dark: rgb(118.15, 98.6, 51.85);
+  --r-link-color-hover: rgb(179.36, 150.84, 82.64);
   --r-selection-background-color: rgba(79, 64, 28, 0.99);
   --r-selection-color: #fff;
   --r-overlay-element-bg-color: 0, 0, 0;

dist/theme/black-contrast.css

@@ -35,9 +35,9 @@ section.has-light-background, section.has-light-background h1, section.has-light
   --r-heading4-size: 1em;
   --r-code-font: monospace;
   --r-link-color: #42affa;
-  --r-link-color-dark: #068de9;
-  --r-link-color-hover: #8dcffc;
-  --r-selection-background-color: #bee4fd;
+  --r-link-color-dark: rgb(19.8216494845, 155.4536082474, 248.7783505155);
+  --r-link-color-hover: rgb(94.35, 187, 250.75);
+  --r-selection-background-color: rgb(113.25, 195, 251.25);
   --r-selection-color: #fff;
   --r-overlay-element-bg-color: 240, 240, 240;
   --r-overlay-element-fg-color: 0, 0, 0;

dist/theme/black.css

@@ -32,8 +32,8 @@ section.has-light-background, section.has-light-background h1, section.has-light
   --r-heading4-size: 1em;
   --r-code-font: monospace;
   --r-link-color: #42affa;
-  --r-link-color-dark: #068de9;
-  --r-link-color-hover: #8dcffc;
+  --r-link-color-dark: rgb(19.8216494845, 155.4536082474, 248.7783505155);
+  --r-link-color-hover: rgb(94.35, 187, 250.75);
   --r-selection-background-color: rgba(66, 175, 250, 0.75);
   --r-selection-color: #fff;
   --r-overlay-element-bg-color: 240, 240, 240;

dist/theme/blood.css

@@ -38,8 +38,8 @@ section.has-light-background, section.has-light-background h1, section.has-light
   --r-heading4-size: 1em;
   --r-code-font: monospace;
   --r-link-color: #a23;
-  --r-link-color-dark: #6a1520;
-  --r-link-color-hover: #dd5566;
+  --r-link-color-dark: rgb(144.5, 28.9, 43.35);
+  --r-link-color-hover: rgb(214.2, 51, 71.4);
   --r-selection-background-color: #a23;
   --r-selection-color: #fff;
   --r-overlay-element-bg-color: 240, 240, 240;

dist/theme/dracula.css

@@ -2,6 +2,8 @@
  * Dracula Dark theme for reveal.js.
  * Based on https://draculatheme.com
  */
+@import url(./fonts/league-gothic/league-gothic.css);
+@import url(https://fonts.googleapis.com/css?family=Lato:400,700,400italic,700italic);
 /**
  * Dracula colors by Zeno Rocha
  * https://draculatheme.com/contribute
@@ -39,7 +41,7 @@ section.has-light-background, section.has-light-background h1, section.has-light
   --r-heading4-size: 1em;
   --r-code-font: Fira Code, Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
   --r-link-color: #FF79C6;
-  --r-link-color-dark: #ff2da5;
+  --r-link-color-dark: rgb(255, 64.6, 174.0089552239);
   --r-link-color-hover: #8BE9FD;
   --r-selection-background-color: #44475A;
   --r-selection-color: #fff;

dist/theme/league.css

@@ -35,8 +35,8 @@ section.has-light-background, section.has-light-background h1, section.has-light
   --r-heading4-size: 1em;
   --r-code-font: monospace;
   --r-link-color: #13DAEC;
-  --r-link-color-dark: #0d99a5;
-  --r-link-color-hover: #71e9f4;
+  --r-link-color-dark: rgb(16.15, 185.3, 200.6);
+  --r-link-color-hover: rgb(66.2, 225.4, 239.8);
   --r-selection-background-color: #FF5E99;
   --r-selection-color: #fff;
   --r-overlay-element-bg-color: 240, 240, 240;

dist/theme/moon.css

@@ -35,8 +35,8 @@ section.has-light-background, section.has-light-background h1, section.has-light
   --r-heading4-size: 1em;
   --r-code-font: monospace;
   --r-link-color: #268bd2;
-  --r-link-color-dark: #1a6091;
-  --r-link-color-hover: #78b9e6;
+  --r-link-color-dark: rgb(32.3, 118.15, 178.5);
+  --r-link-color-hover: rgb(77.5161290323, 162.8774193548, 222.8838709677);
   --r-selection-background-color: #d33682;
   --r-selection-color: #fff;
   --r-overlay-element-bg-color: 240, 240, 240;

dist/theme/night.css

@@ -33,8 +33,8 @@ section.has-light-background, section.has-light-background h1, section.has-light
   --r-heading4-size: 1em;
   --r-code-font: monospace;
   --r-link-color: #e7ad52;
-  --r-link-color-dark: #d08a1d;
-  --r-link-color-hover: #f3d7ac;
+  --r-link-color-dark: rgb(225.2802030457, 153.4573604061, 40.7697969543);
+  --r-link-color-hover: rgb(235.8, 189.4, 116.6);
   --r-selection-background-color: #e7ad52;
   --r-selection-color: #fff;
   --r-overlay-element-bg-color: 240, 240, 240;

dist/theme/serif.css

@@ -36,8 +36,8 @@ section.has-dark-background, section.has-dark-background h1, section.has-dark-ba
   --r-heading4-size: 1em;
   --r-code-font: monospace;
   --r-link-color: #51483D;
-  --r-link-color-dark: #25211c;
-  --r-link-color-hover: #8b7c69;
+  --r-link-color-dark: rgb(68.85, 61.2, 51.85);
+  --r-link-color-hover: rgb(122.9830985915, 109.3183098592, 92.6169014085);
   --r-selection-background-color: #26351C;
   --r-selection-color: #fff;
   --r-overlay-element-bg-color: 0, 0, 0;

dist/theme/simple.css

@@ -35,8 +35,8 @@ section.has-dark-background, section.has-dark-background h1, section.has-dark-ba
   --r-heading4-size: 1em;
   --r-code-font: monospace;
   --r-link-color: #00008B;
-  --r-link-color-dark: #00003f;
-  --r-link-color-hover: #0000f1;
+  --r-link-color-dark: rgb(0, 0, 118.15);
+  --r-link-color-hover: rgb(0, 0, 213.2);
   --r-selection-background-color: rgba(0, 0, 0, 0.99);
   --r-selection-color: #fff;
   --r-overlay-element-bg-color: 0, 0, 0;

dist/theme/sky.css

@@ -37,8 +37,8 @@ section.has-dark-background, section.has-dark-background h1, section.has-dark-ba
   --r-heading4-size: 1em;
   --r-code-font: monospace;
   --r-link-color: #3b759e;
-  --r-link-color-dark: #264c66;
-  --r-link-color-hover: #74a7cb;
+  --r-link-color-dark: rgb(50.15, 99.45, 134.3);
+  --r-link-color-hover: rgb(84.330875576, 146.9815668203, 191.269124424);
   --r-selection-background-color: #134674;
   --r-selection-color: #fff;
   --r-overlay-element-bg-color: 0, 0, 0;

dist/theme/solarized.css

@@ -36,8 +36,8 @@ html * {
   --r-heading4-size: 1em;
   --r-code-font: monospace;
   --r-link-color: #268bd2;
-  --r-link-color-dark: #1a6091;
-  --r-link-color-hover: #78b9e6;
+  --r-link-color-dark: rgb(32.3, 118.15, 178.5);
+  --r-link-color-hover: rgb(77.5161290323, 162.8774193548, 222.8838709677);
   --r-selection-background-color: #d33682;
   --r-selection-color: #fff;
   --r-overlay-element-bg-color: 0, 0, 0;

dist/theme/white-contrast.css

@@ -35,9 +35,9 @@ section.has-dark-background, section.has-dark-background h1, section.has-dark-ba
   --r-heading4-size: 1em;
   --r-code-font: monospace;
   --r-link-color: #2a76dd;
-  --r-link-color-dark: #1a53a1;
-  --r-link-color-hover: #6ca0e8;
-  --r-selection-background-color: #98bdef;
+  --r-link-color-dark: rgb(30.7720647773, 99.5566801619, 192.7779352227);
+  --r-link-color-hover: rgb(73.95, 138.55, 226.1);
+  --r-selection-background-color: rgb(95.25, 152.25, 229.5);
   --r-selection-color: #fff;
   --r-overlay-element-bg-color: 0, 0, 0;
   --r-overlay-element-fg-color: 240, 240, 240;

dist/theme/white.css

@@ -32,9 +32,9 @@ section.has-dark-background, section.has-dark-background h1, section.has-dark-ba
   --r-heading4-size: 1em;
   --r-code-font: monospace;
   --r-link-color: #2a76dd;
-  --r-link-color-dark: #1a53a1;
-  --r-link-color-hover: #6ca0e8;
-  --r-selection-background-color: #98bdef;
+  --r-link-color-dark: rgb(30.7720647773, 99.5566801619, 192.7779352227);
+  --r-link-color-hover: rgb(73.95, 138.55, 226.1);
+  --r-selection-background-color: rgb(95.25, 152.25, 229.5);
   --r-selection-color: #fff;
   --r-overlay-element-bg-color: 0, 0, 0;
   --r-overlay-element-fg-color: 240, 240, 240;

examples/backgrounds.html

@@ -89,7 +89,7 @@
 					<h2>Same background twice (2/2)</h2>
 				</section>
 
-				<section data-background-video="https://s3.amazonaws.com/static.slid.es/site/homepage/v1/homepage-video-editor.mp4,https://s3.amazonaws.com/static.slid.es/site/homepage/v1/homepage-video-editor.webm">
+				<section data-background-video="https://static.slid.es/site/homepage/v1/homepage-video-editor.mp4,https://static.slid.es/site/homepage/v1/homepage-video-editor.webm">
 					<h2>Video background</h2>
 				</section>
 

examples/lightbox.html

@@ -0,0 +1,144 @@
+<!doctype html>
+<html lang="en">
+
+	<head>
+		<meta charset="utf-8">
+
+		<title>reveal.js - Ligthbox</title>
+
+		<link rel="stylesheet" href="../dist/reveal.css">
+		<link rel="stylesheet" href="../dist/theme/black.css" id="theme">
+
+		<style>
+			.reveal {
+				font-size: 24px;
+			}
+			.reveal figure {
+				margin: 0 0 1rem 0;
+				text-align: left;
+			}
+			.reveal figure img,
+			.reveal figure video {
+				margin: 0.25rem 0 0 0;
+			}
+			figcaption, a {
+				font-size: 16px;
+			}
+		</style>
+	</head>
+
+	<body>
+
+		<div class="reveal">
+
+			<div class="slides">
+
+				<section>
+
+					<h2>Preview Overlays</h2>
+
+					<div class="r-hstack items-start">
+						<div class="r-vstack items-start">
+							<h5>Images</h5>
+							<figure>
+								<figcaption>Preview with default settings:</figcaption>
+								<img height="50" src="https://static.slid.es/images/alphabet/v1/a.png" data-preview-image>
+							</figure>
+							<figure>
+								<figcaption>Preview with data-preview-fit="contain"</figcaption>
+								<img height="50" src="https://static.slid.es/images/alphabet/v1/a.png" data-preview-image data-preview-fit="contain">
+							</figure>
+							<figure>
+								<figcaption>Preview with data-preview-fit="cover"</figcaption>
+								<img height="50" src="https://static.slid.es/images/alphabet/v1/a.png" data-preview-image data-preview-fit="cover">
+							</figure>
+							<figure>
+								<figcaption>Preview another image (c)</figcaption>
+								<img height="50" src="https://static.slid.es/images/alphabet/v1/b.png" data-preview-image="https://static.slid.es/images/alphabet/v1/c.png">
+							</figure>
+							<a href="#" data-preview-image="https://static.slid.es/images/alphabet/v1/x.png">
+								Preview image from a link.
+							</a>
+						</div>
+
+						<div style="width: 1px; height: 30vh; margin: 0 3rem;background-color: #999;"></div>
+
+						<div class="r-vstack items-start">
+							<h5>Videos</h5>
+							<figure>
+								<figcaption>Preview video</figcaption>
+								<img height="50" src="https://static.slid.es/images/alphabet/v1/x.png" data-preview-video="https://static.slid.es/site/homepage/v1/homepage-video-editor.mp4">
+							</figure>
+							<figure>
+								<figcaption>Preview video</figcaption>
+								<video height="50" src="https://static.slid.es/site/homepage/v1/homepage-video-editor.mp4" data-preview-video></video>
+							</figure>
+							<a href="#" data-preview-video="https://static.slid.es/site/homepage/v1/homepage-video-editor.mp4">
+								Preview video from a link.
+							</a>
+						</div>
+
+						<div style="width: 1px; height: 30vh; margin: 0 3rem;background-color: #999;"></div>
+
+						<div class="r-vstack items-start">
+							<h5>Iframes</h5>
+							<a href="https://hakim.se">https://hakim.se | data-preview-link</a>
+							<a data-preview-link href="https://hakim.se">https://hakim.se | data-preview-link</a>
+							<br />
+							<a data-preview-link="false" href="https://hakim.se">https://hakim.se | data-preview-link=false</a>
+							<br />
+							<figure>
+								<figcaption>Preview link from an image</figcaption>
+								<img height="50" src="https://static.slid.es/images/alphabet/v1/a.png" data-preview-link="https://hakim.se">
+							</figure>
+						</div>
+					</div>
+
+				</section>
+
+				<section style="text-align: left;">
+
+					<h2>Lightbox</h2>
+
+					<div class="r-hstack items-start justify-start">
+						<div class="r-vstack items-start">
+							<h5>Images</h5>
+							<figure>
+								<img height="100" src="https://static.slid.es/images/alphabet/v1/a.png" data-preview-image data-preview-fit="contain">
+							</figure>
+						</div>
+
+						<div style="width: 1px; height: 20vh; margin: 0 3rem;background-color: #222;"></div>
+
+						<div class="r-vstack items-start">
+							<h5>Videos</h5>
+							<figure>
+								<video height="100" src="https://static.slid.es/site/homepage/v1/homepage-video-editor.mp4" data-preview-video></video>
+							</figure>
+						</div>
+
+						<div style="width: 1px; height: 20vh; margin: 0 3rem;background-color: #222;"></div>
+
+						<div class="r-vstack items-start">
+							<h5>Iframes</h5>
+							<a style="font-size: 28px;" data-preview-link href="https://hakim.se">https://hakim.se</a>
+						</div>
+					</div>
+
+				</section>
+
+			</div>
+
+		</div>
+
+		<script src="../dist/reveal.js"></script>
+		<script>
+			Reveal.initialize({
+				previewLinks: false,
+				width: 1280,
+				height: 720
+			});
+		</script>
+
+	</body>
+</html>

examples/markdown.html

@@ -121,7 +121,7 @@
                 <!-- Images -->
                 <section data-markdown>
                     <script type="text/template">
-                        ![Sample image](https://s3.amazonaws.com/static.slid.es/logo/v2/slides-symbol-512x512.png)
+                        ![Sample image](https://static.slid.es/logo/v2/slides-symbol-512x512.png)
                     </script>
                 </section>
 

examples/markdown.md

@@ -33,7 +33,7 @@ Content 3.2
 
 ## External 3.3 (Image)
 
-![External Image](https://s3.amazonaws.com/static.slid.es/logo/v2/slides-symbol-512x512.png)
+![External Image](https://static.slid.es/logo/v2/slides-symbol-512x512.png)
 
 
 ## External 3.4 (Math)

examples/media.html

@@ -33,10 +33,10 @@
 
 				<section>
 					<h2>Video</h2>
-					<video src="http://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4" data-autoplay></video>
+					<video src="https://static.slid.es/site/homepage/v1/homepage-video-editor.mp4" data-autoplay></video>
 				</section>
 
-				<section data-background-video="http://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4">
+				<section data-background-video="https://static.slid.es/site/homepage/v1/homepage-video-editor.mp4">
 					<h2>Background Video</h2>
 				</section>
 

examples/scroll.html

@@ -91,8 +91,10 @@
           <section data-background="https://static.slid.es/reveal/image-placeholder.png" id="image-bg">
             <h2>Image Backgrounds</h2>
           </section>
-          <section data-background-video-muted data-background-video="https://s3.amazonaws.com/static.slid.es/site/homepage/v1/homepage-video-editor.mp4,https://s3.amazonaws.com/static.slid.es/site/homepage/v1/homepage-video-editor.webm">
-            <h2>Video background</h2>
+          <section data-background-video-muted data-background-video="https://static.slid.es/site/homepage/v1/homepage-video-editor.mp4,https://static.slid.es/site/homepage/v1/homepage-video-editor.webm">
+            <div style="background-color: rgba(0, 0, 0, 0.9); color: #fff; padding: 20px;">
+              <h2>Video background</h2>
+            </div>
           </section>
         </section>
 				<section><h2>The end</h2></section>

gulpfile.js

@@ -1,3 +1,4 @@
+const fs = require('fs');
 const pkg = require('./package.json')
 const glob = require('glob')
 const yargs = require('yargs')
@@ -12,9 +13,8 @@ const resolve = require('@rollup/plugin-node-resolve').default
 const sass = require('sass')
 
 const gulp = require('gulp')
-const tap = require('gulp-tap')
 const zip = require('gulp-zip')
-const header = require('gulp-header')
+const header = require('gulp-header-comment')
 const eslint = require('gulp-eslint')
 const minify = require('gulp-clean-css')
 const connect = require('gulp-connect')
@@ -24,13 +24,21 @@ const root = yargs.argv.root || '.'
 const port = yargs.argv.port || 8000
 const host = yargs.argv.host || 'localhost'
 
-const banner = `/*!
-* reveal.js ${pkg.version}
-* ${pkg.homepage}
-* MIT licensed
-*
-* Copyright (C) 2011-2024 Hakim El Hattab, https://hakim.se
-*/\n`
+const cssLicense = `
+reveal.js ${pkg.version}
+${pkg.homepage}
+MIT licensed
+
+Copyright (C) 2011-2024 Hakim El Hattab, https://hakim.se
+`;
+
+const jsLicense = `/*!
+ * reveal.js ${pkg.version}
+ * ${pkg.homepage}
+ * MIT licensed
+ *
+ * Copyright (C) 2011-2024 Hakim El Hattab, https://hakim.se
+ */\n`;
 
 // Prevents warnings from opening too many test pages
 process.setMaxListeners(20);
@@ -86,7 +94,7 @@ gulp.task('js-es5', () => {
             name: 'Reveal',
             file: './dist/reveal.js',
             format: 'umd',
-            banner: banner,
+            banner: jsLicense,
             sourcemap: true
         });
     });
@@ -108,7 +116,7 @@ gulp.task('js-es6', () => {
         return bundle.write({
             file: './dist/reveal.esm.js',
             format: 'es',
-            banner: banner,
+            banner: jsLicense,
             sourcemap: true
         });
     });
@@ -161,6 +169,7 @@ function compileSass() {
     const transformedFile = vinylFile.clone();
 
     sass.render({
+        silenceDeprecations: ['legacy-js-api'],
         data: transformedFile.contents.toString(),
         file: transformedFile.path,
     }, ( err, result ) => {
@@ -184,7 +193,7 @@ gulp.task('css-core', () => gulp.src(['css/reveal.scss'])
     .pipe(compileSass())
     .pipe(autoprefixer())
     .pipe(minify({compatibility: 'ie9'}))
-    .pipe(header(banner))
+    .pipe(header(cssLicense))
     .pipe(gulp.dest('./dist')))
 
 gulp.task('css', gulp.parallel('css-themes', 'css-core'))
@@ -211,7 +220,7 @@ gulp.task('qunit', () => {
                 targetUrl: `http://${serverConfig.host}:${serverConfig.port}/${filename}`,
                 timeout: 20000,
                 redirectConsole: false,
-                puppeteerArgs: ['--allow-file-access-from-files']
+                puppeteerArgs: ['--allow-file-access-from-files', '--no-sandbox']
             })
                 .then(result => {
                     if( result.stats.failed > 0 ) {
@@ -266,22 +275,23 @@ gulp.task('default', gulp.series(gulp.parallel('js', 'css', 'plugins'), 'test'))
 
 gulp.task('build', gulp.parallel('js', 'css', 'plugins'))
 
-gulp.task('package', gulp.series(() =>
+gulp.task('package', gulp.series(async () => {
 
-    gulp.src(
-        [
-            './index.html',
-            './dist/**',
-            './lib/**',
-            './images/**',
-            './plugin/**',
-            './**/*.md'
-        ],
-        { base: './' }
-    )
+    let dirs = [
+        './index.html',
+        './dist/**',
+        './plugin/**',
+        './*/*.md'
+    ];
+
+    if (fs.existsSync('./lib')) dirs.push('./lib/**');
+    if (fs.existsSync('./images')) dirs.push('./images/**');
+    if (fs.existsSync('./slides')) dirs.push('./slides/**');
+
+    return gulp.src( dirs, { base: './', encoding: false } )
     .pipe(zip('reveal-js-presentation.zip')).pipe(gulp.dest('./'))
 
-))
+}))
 
 gulp.task('reload', () => gulp.src(['index.html'])
     .pipe(connect.reload()));

js/config.js

@@ -15,7 +15,10 @@ export default {
 	minScale: 0.2,
 	maxScale: 2.0,
 
-	// Display presentation control arrows
+	// Display presentation control arrows.
+	// - true: Display controls on all screens
+	// - false: Hide controls on all screens
+	// - "speaker-only": Only display controls in the speaker view
 	controls: true,
 
 	// Help the user learn the controls by providing hints, for example by
@@ -74,7 +77,7 @@ export default {
 	// Enable keyboard shortcuts for navigation
 	keyboard: true,
 
-	// Optional function that blocks keyboard events when retuning false
+	// Optional function that blocks keyboard events when returning false
 	//
 	// If you set this to 'focused', we will only capture keyboard events
 	// for embedded decks when they are in focus

js/controllers/autoanimate.js

@@ -31,10 +31,13 @@ export default class AutoAnimate {
 		let toSlideIndex = allSlides.indexOf( toSlide );
 		let fromSlideIndex = allSlides.indexOf( fromSlide );
 
-		// Ensure that both slides are auto-animate targets with the same data-auto-animate-id value
-		// (including null if absent on both) and that data-auto-animate-restart isn't set on the
-		// physically latter slide (independent of slide direction)
-		if( fromSlide.hasAttribute( 'data-auto-animate' ) && toSlide.hasAttribute( 'data-auto-animate' )
+		// Ensure that;
+		// 1. Both slides exist.
+		// 2. Both slides are auto-animate targets with the same
+		//    data-auto-animate-id value (including null if absent on both).
+		// 3. data-auto-animate-restart isn't set on the physically latter
+		//    slide (independent of slide direction).
+		if( fromSlide && toSlide && fromSlide.hasAttribute( 'data-auto-animate' ) && toSlide.hasAttribute( 'data-auto-animate' )
 				&& fromSlide.getAttribute( 'data-auto-animate-id' ) === toSlide.getAttribute( 'data-auto-animate-id' ) 
 				&& !( toSlideIndex > fromSlideIndex ? toSlide : fromSlide ).hasAttribute( 'data-auto-animate-restart' ) ) {
 
@@ -175,28 +178,12 @@ export default class AutoAnimate {
 		let fromProps = this.getAutoAnimatableProperties( 'from', from, elementOptions ),
 			toProps = this.getAutoAnimatableProperties( 'to', to, elementOptions );
 
-		// Maintain fragment visibility for matching elements when
-		// we're navigating forwards, this way the viewer won't need
-		// to step through the same fragments twice
 		if( to.classList.contains( 'fragment' ) ) {
 
 			// Don't auto-animate the opacity of fragments to avoid
 			// conflicts with fragment animations
 			delete toProps.styles['opacity'];
 
-			if( from.classList.contains( 'fragment' ) ) {
-
-				let fromFragmentStyle = ( from.className.match( FRAGMENT_STYLE_REGEX ) || [''] )[0];
-				let toFragmentStyle = ( to.className.match( FRAGMENT_STYLE_REGEX ) || [''] )[0];
-
-				// Only skip the fragment if the fragment animation style
-				// remains unchanged
-				if( fromFragmentStyle === toFragmentStyle && animationOptions.slideDirection === 'forward' ) {
-					to.classList.add( 'visible', 'disabled' );
-				}
-
-			}
-
 		}
 
 		// If translation and/or scaling are enabled, css transform
@@ -468,7 +455,7 @@ export default class AutoAnimate {
 
 		// Text
 		this.findAutoAnimateMatches( pairs, fromSlide, toSlide, textNodes, node => {
-			return node.nodeName + ':::' + node.innerText;
+			return node.nodeName + ':::' + node.textContent.trim();
 		} );
 
 		// Media
@@ -478,7 +465,7 @@ export default class AutoAnimate {
 
 		// Code
 		this.findAutoAnimateMatches( pairs, fromSlide, toSlide, codeNodes, node => {
-			return node.nodeName + ':::' + node.innerText;
+			return node.nodeName + ':::' + node.textContent.trim();
 		} );
 
 		pairs.forEach( pair => {

js/controllers/backgrounds.js

@@ -268,14 +268,15 @@ export default class Backgrounds {
 	 */
 	update( includeAll = false ) {
 
+		let config = this.Reveal.getConfig();
 		let currentSlide = this.Reveal.getCurrentSlide();
 		let indices = this.Reveal.getIndices();
 
 		let currentBackground = null;
 
 		// Reverse past/future classes when in RTL mode
-		let horizontalPast = this.Reveal.getConfig().rtl ? 'future' : 'past',
-			horizontalFuture = this.Reveal.getConfig().rtl ? 'past' : 'future';
+		let horizontalPast = config.rtl ? 'future' : 'past',
+			horizontalFuture = config.rtl ? 'past' : 'future';
 
 		// Update the classes of all backgrounds to match the
 		// states of their slides (past/present/future)
@@ -321,15 +322,53 @@ export default class Backgrounds {
 
 		} );
 
+		// The previous background may refer to a DOM element that has
+		// been removed after a presentation is synced & bgs are recreated
+		if( this.previousBackground && !this.previousBackground.closest( 'body' ) ) {
+			this.previousBackground = null;
+		}
+
+		if( currentBackground && this.previousBackground ) {
+
+			// Don't transition between identical backgrounds. This
+			// prevents unwanted flicker.
+			let previousBackgroundHash = this.previousBackground.getAttribute( 'data-background-hash' );
+			let currentBackgroundHash = currentBackground.getAttribute( 'data-background-hash' );
+
+			if( currentBackgroundHash && currentBackgroundHash === previousBackgroundHash && currentBackground !== this.previousBackground ) {
+				this.element.classList.add( 'no-transition' );
+
+				// If multiple slides have the same background video, carry
+				// the <video> element forward so that it plays continuously
+				// across multiple slides
+				const currentVideo = currentBackground.querySelector( 'video' );
+				const previousVideo = this.previousBackground.querySelector( 'video' );
+
+				if( currentVideo && previousVideo ) {
+
+					const currentVideoParent = currentVideo.parentNode;
+					const previousVideoParent = previousVideo.parentNode;
+
+					// Swap the two videos
+					previousVideoParent.appendChild( currentVideo );
+					currentVideoParent.appendChild( previousVideo );
+
+				}
+			}
+
+		}
+
+		const backgroundChanged = currentBackground !== this.previousBackground;
+
 		// Stop content inside of previous backgrounds
-		if( this.previousBackground ) {
+		if( backgroundChanged && this.previousBackground ) {
 
 			this.Reveal.slideContent.stopEmbeddedContent( this.previousBackground, { unloadIframes: !this.Reveal.slideContent.shouldPreload( this.previousBackground ) } );
 
 		}
 
 		// Start content in the current background
-		if( currentBackground ) {
+		if( backgroundChanged && currentBackground ) {
 
 			this.Reveal.slideContent.startEmbeddedContent( currentBackground );
 
@@ -347,14 +386,6 @@ export default class Backgrounds {
 
 			}
 
-			// Don't transition between identical backgrounds. This
-			// prevents unwanted flicker.
-			let previousBackgroundHash = this.previousBackground ? this.previousBackground.getAttribute( 'data-background-hash' ) : null;
-			let currentBackgroundHash = currentBackground.getAttribute( 'data-background-hash' );
-			if( currentBackgroundHash && currentBackgroundHash === previousBackgroundHash && currentBackground !== this.previousBackground ) {
-				this.element.classList.add( 'no-transition' );
-			}
-
 			this.previousBackground = currentBackground;
 
 		}
@@ -368,7 +399,7 @@ export default class Backgrounds {
 		// Allow the first background to apply without transition
 		setTimeout( () => {
 			this.element.classList.remove( 'no-transition' );
-		}, 1 );
+		}, 10 );
 
 	}
 

js/controllers/controls.js

@@ -1,4 +1,4 @@
-import { queryAll } from '../utils/util.js'
+import { queryAll, enterFullscreen } from '../utils/util.js'
 import { isAndroid } from '../utils/device.js'
 
 /**
@@ -12,6 +12,7 @@ import { isAndroid } from '../utils/device.js'
  * - .navigate-left
  * - .navigate-next
  * - .navigate-prev
+ * - .enter-fullscreen
  */
 export default class Controls {
 
@@ -25,6 +26,7 @@ export default class Controls {
 		this.onNavigateDownClicked = this.onNavigateDownClicked.bind( this );
 		this.onNavigatePrevClicked = this.onNavigatePrevClicked.bind( this );
 		this.onNavigateNextClicked = this.onNavigateNextClicked.bind( this );
+		this.onEnterFullscreen = this.onEnterFullscreen.bind( this );
 
 	}
 
@@ -50,6 +52,7 @@ export default class Controls {
 		this.controlsDown = queryAll( revealElement, '.navigate-down' );
 		this.controlsPrev = queryAll( revealElement, '.navigate-prev' );
 		this.controlsNext = queryAll( revealElement, '.navigate-next' );
+		this.controlsFullscreen = queryAll( revealElement, '.enter-fullscreen' );
 
 		// The left, right and down arrows in the standard reveal.js controls
 		this.controlsRightArrow = this.element.querySelector( '.navigate-right' );
@@ -63,7 +66,10 @@ export default class Controls {
 	 */
 	configure( config, oldConfig ) {
 
-		this.element.style.display = config.controls ? 'block' : 'none';
+		this.element.style.display = (
+			config.controls &&
+			(config.controls !== 'speaker-only' || this.Reveal.isSpeakerNotes())
+		) ? 'block' : 'none';
 
 		this.element.setAttribute( 'data-controls-layout', config.controlsLayout );
 		this.element.setAttribute( 'data-controls-back-arrows', config.controlsBackArrows );
@@ -77,9 +83,10 @@ export default class Controls {
 		let pointerEvents = [ 'touchstart', 'click' ];
 
 		// Only support touch for Android, fixes double navigations in
-		// stock browser
+		// stock browser. Use touchend for it to be considered a valid
+		// user interaction (so we're allowed to autoplay media).
 		if( isAndroid ) {
-			pointerEvents = [ 'touchstart' ];
+			pointerEvents = [ 'touchend' ];
 		}
 
 		pointerEvents.forEach( eventName => {
@@ -89,19 +96,21 @@ export default class Controls {
 			this.controlsDown.forEach( el => el.addEventListener( eventName, this.onNavigateDownClicked, false ) );
 			this.controlsPrev.forEach( el => el.addEventListener( eventName, this.onNavigatePrevClicked, false ) );
 			this.controlsNext.forEach( el => el.addEventListener( eventName, this.onNavigateNextClicked, false ) );
+			this.controlsFullscreen.forEach( el => el.addEventListener( eventName, this.onEnterFullscreen, false ) );
 		} );
 
 	}
 
 	unbind() {
 
-		[ 'touchstart', 'click' ].forEach( eventName => {
+		[ 'touchstart', 'touchend', 'click' ].forEach( eventName => {
 			this.controlsLeft.forEach( el => el.removeEventListener( eventName, this.onNavigateLeftClicked, false ) );
 			this.controlsRight.forEach( el => el.removeEventListener( eventName, this.onNavigateRightClicked, false ) );
 			this.controlsUp.forEach( el => el.removeEventListener( eventName, this.onNavigateUpClicked, false ) );
 			this.controlsDown.forEach( el => el.removeEventListener( eventName, this.onNavigateDownClicked, false ) );
 			this.controlsPrev.forEach( el => el.removeEventListener( eventName, this.onNavigatePrevClicked, false ) );
 			this.controlsNext.forEach( el => el.removeEventListener( eventName, this.onNavigateNextClicked, false ) );
+			this.controlsFullscreen.forEach( el => el.removeEventListener( eventName, this.onEnterFullscreen, false ) );
 		} );
 
 	}
@@ -141,9 +150,14 @@ export default class Controls {
 			if( fragmentsRoutes.prev ) this.controlsPrev.forEach( el => { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute( 'disabled' ); } );
 			if( fragmentsRoutes.next ) this.controlsNext.forEach( el => { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute( 'disabled' ); } );
 
+			const isVerticalStack = this.Reveal.isVerticalSlide( currentSlide );
+			const hasVerticalSiblings = isVerticalStack &&
+																	currentSlide.parentElement &&
+																	currentSlide.parentElement.querySelectorAll( ':scope > section' ).length > 1;
+
 			// Apply fragment decorators to directional buttons based on
 			// what slide axis they are in
-			if( this.Reveal.isVerticalSlide( currentSlide ) ) {
+			if( isVerticalStack && hasVerticalSiblings ) {
 				if( fragmentsRoutes.prev ) this.controlsUp.forEach( el => { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute( 'disabled' ); } );
 				if( fragmentsRoutes.next ) this.controlsDown.forEach( el => { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute( 'disabled' ); } );
 			}
@@ -262,5 +276,13 @@ export default class Controls {
 
 	}
 
+	onEnterFullscreen( event ) {
+
+		const config = this.Reveal.getConfig();
+		const viewport = this.Reveal.getViewportElement();
+
+		enterFullscreen( config.embedded ? viewport : viewport.parentElement );
+
+	}
 
 }

js/controllers/jumptoslide.js

@@ -74,7 +74,7 @@ export default class JumpToSlide {
 		let query = this.jumpInput.value.trim( '' );
 		let indices;
 
-		// When slide numbers are formatted to be a single linear mumber
+		// When slide numbers are formatted to be a single linear number
 		// (instead of showing a separate horizontal/vertical index) we
 		// use the same format for slide jumps
 		if( /^\d+$/.test( query ) ) {

js/controllers/keyboard.js

@@ -167,7 +167,7 @@ export default class Keyboard {
 		let activeElementIsNotes = document.activeElement && document.activeElement.className && /speaker-notes/i.test( document.activeElement.className);
 
 		// Whitelist certain modifiers for slide navigation shortcuts
-		let keyCodeUsesModifier = [32, 37, 38, 39, 40, 78, 80, 191].indexOf( event.keyCode ) !== -1;
+		let keyCodeUsesModifier = [32, 37, 38, 39, 40, 63, 78, 80, 191].indexOf( event.keyCode ) !== -1;
 
 		// Prevent all other events when a modifier is pressed
 		let unusedModifier = 	!( keyCodeUsesModifier && event.shiftKey || event.altKey ) &&
@@ -190,6 +190,10 @@ export default class Keyboard {
 			}
 		}
 
+		if( this.Reveal.isOverlayOpen() && !["Escape", "f", "c", "b", "."].includes(event.key) ) {
+			return false;
+		}
+
 		if( this.Reveal.isPaused() && resumeKeyCodes.indexOf( keyCode ) === -1 ) {
 			return false;
 		}
@@ -271,7 +275,12 @@ export default class Keyboard {
 					this.Reveal.slide( 0 );
 				}
 				else if( !this.Reveal.overview.isActive() && useLinearMode ) {
-					this.Reveal.prev({skipFragments: event.altKey});
+					if( config.rtl ) {
+						this.Reveal.next({skipFragments: event.altKey});
+					}
+					else {
+						this.Reveal.prev({skipFragments: event.altKey});
+					}
 				}
 				else {
 					this.Reveal.left({skipFragments: event.altKey});
@@ -283,7 +292,12 @@ export default class Keyboard {
 					this.Reveal.slide( this.Reveal.getHorizontalSlides().length - 1 );
 				}
 				else if( !this.Reveal.overview.isActive() && useLinearMode ) {
-					this.Reveal.next({skipFragments: event.altKey});
+					if( config.rtl ) {
+						this.Reveal.prev({skipFragments: event.altKey});
+					}
+					else {
+						this.Reveal.next({skipFragments: event.altKey});
+					}
 				}
 				else {
 					this.Reveal.right({skipFragments: event.altKey});
@@ -353,8 +367,12 @@ export default class Keyboard {
 					this.Reveal.toggleJumpToSlide();
 				}
 			}
+			// C
+			else if( keyCode === 67 && this.Reveal.isOverlayOpen() ) {
+				this.Reveal.closeOverlay();
+			}
 			// ?
-			else if( keyCode === 191 && event.shiftKey ) {
+			else if( ( keyCode === 63 || keyCode === 191 ) && event.shiftKey ) {
 				this.Reveal.toggleHelp();
 			}
 			// F1
@@ -380,6 +398,12 @@ export default class Keyboard {
 
 			event.preventDefault && event.preventDefault();
 		}
+		
+		// Enter to exit overview mode
+		else if (keyCode === 13 && this.Reveal.overview.isActive()) {
+			this.Reveal.overview.deactivate();
+			event.preventDefault && event.preventDefault();
+		}
 
 		// If auto-sliding is enabled we need to cue up
 		// another timeout

js/controllers/overlay.js

@@ -0,0 +1,389 @@
+/**
+ * Handles the display of reveal.js' overlay elements used
+ * to preview iframes, images & videos.
+ */
+export default class Overlay {
+
+	constructor( Reveal ) {
+
+		this.Reveal = Reveal;
+
+		this.onSlidesClicked = this.onSlidesClicked.bind( this );
+
+		this.iframeTriggerSelector = null;
+		this.mediaTriggerSelector = '[data-preview-image], [data-preview-video]';
+
+		this.stateProps = ['previewIframe', 'previewImage', 'previewVideo', 'previewFit'];
+		this.state = {};
+
+	}
+
+	update() {
+
+		// Enable link previews globally
+		if( this.Reveal.getConfig().previewLinks ) {
+			this.iframeTriggerSelector = 'a[href]:not([data-preview-link=false]), [data-preview-link]:not(a):not([data-preview-link=false])';
+		}
+		// Enable link previews for individual elements
+		else {
+			this.iframeTriggerSelector = '[data-preview-link]:not([data-preview-link=false])';
+		}
+
+		const hasLinkPreviews = this.Reveal.getSlidesElement().querySelectorAll( this.iframeTriggerSelector ).length > 0;
+		const hasMediaPreviews = this.Reveal.getSlidesElement().querySelectorAll( this.mediaTriggerSelector ).length > 0;
+
+		// Only add the listener when there are previewable elements in the slides
+		if( hasLinkPreviews || hasMediaPreviews ) {
+			this.Reveal.getSlidesElement().addEventListener( 'click', this.onSlidesClicked, false );
+		}
+		else {
+			this.Reveal.getSlidesElement().removeEventListener( 'click', this.onSlidesClicked, false );
+		}
+
+	}
+
+	createOverlay( className ) {
+
+		this.dom = document.createElement( 'div' );
+		this.dom.classList.add( 'r-overlay' );
+		this.dom.classList.add( className );
+
+		this.viewport = document.createElement( 'div' );
+		this.viewport.classList.add( 'r-overlay-viewport' );
+
+		this.dom.appendChild( this.viewport );
+		this.Reveal.getRevealElement().appendChild( this.dom );
+
+	}
+
+	/**
+	 * Opens a lightbox that previews the target URL.
+	 *
+	 * @param {string} url - url for lightbox iframe src
+	 */
+	previewIframe( url ) {
+
+		this.close();
+
+		this.state = { previewIframe: url };
+
+		this.createOverlay( 'r-overlay-preview' );
+		this.dom.dataset.state = 'loading';
+
+		this.viewport.innerHTML =
+			`<header class="r-overlay-header">
+				<a class="r-overlay-button r-overlay-external" href="${url}" target="_blank"><span class="icon"></span></a>
+				<button class="r-overlay-button r-overlay-close"><span class="icon"></span></button>
+			</header>
+			<div class="r-overlay-spinner"></div>
+			<div class="r-overlay-content">
+				<iframe src="${url}"></iframe>
+				<small class="r-overlay-content-inner">
+					<span class="r-overlay-error x-frame-error">Unable to load iframe. This is likely due to the site's policy (x-frame-options).</span>
+				</small>
+			</div>`;
+
+		this.dom.querySelector( 'iframe' ).addEventListener( 'load', event => {
+			this.dom.dataset.state = 'loaded';
+		}, false );
+
+		this.dom.querySelector( '.r-overlay-close' ).addEventListener( 'click', event => {
+			this.close();
+			event.preventDefault();
+		}, false );
+
+		this.dom.querySelector( '.r-overlay-external' ).addEventListener( 'click', event => {
+			this.close();
+		}, false );
+
+		this.Reveal.dispatchEvent({ type: 'previewiframe', data: { url } });
+
+	}
+
+	/**
+	 * Opens a lightbox window that provides a larger view of the
+	 * given image/video.
+	 *
+	 * @param {string} url - url to the image/video to preview
+	 * @param {image|video} mediaType
+	 * @param {string} [fitMode] - the fit mode to use for the preview
+	 */
+	previewMedia( url, mediaType, fitMode ) {
+
+		if( mediaType !== 'image' && mediaType !== 'video' ) {
+			console.warn( 'Please specify a valid media type to preview (image|video)' );
+			return;
+		}
+
+		this.close();
+
+		fitMode = fitMode || 'scale-down';
+
+		this.createOverlay( 'r-overlay-preview' );
+		this.dom.dataset.state = 'loading';
+		this.dom.dataset.previewFit = fitMode;
+
+		this.viewport.innerHTML =
+			`<header class="r-overlay-header">
+				<button class="r-overlay-button r-overlay-close">Esc <span class="icon"></span></button>
+			</header>
+			<div class="r-overlay-spinner"></div>
+			<div class="r-overlay-content"></div>`;
+
+		const contentElement = this.dom.querySelector( '.r-overlay-content' );
+
+		if( mediaType === 'image' ) {
+
+			this.state = { previewImage: url, previewFit: fitMode }
+
+			const img = document.createElement( 'img', {} );
+			img.src = url;
+			contentElement.appendChild( img );
+
+			img.addEventListener( 'load', () => {
+				this.dom.dataset.state = 'loaded';
+			}, false );
+
+			img.addEventListener( 'error', () => {
+				this.dom.dataset.state = 'error';
+				contentElement.innerHTML =
+						`<span class="r-overlay-error">Unable to load image.</span>`
+			}, false );
+
+			// Hide image overlays when clicking outside the overlay
+			this.dom.style.cursor = 'zoom-out';
+			this.dom.addEventListener( 'click', ( event ) => {
+				this.close();
+			}, false );
+
+			this.Reveal.dispatchEvent({ type: 'previewimage', data: { url } });
+
+		}
+		else if( mediaType === 'video' ) {
+
+			this.state = { previewVideo: url, previewFit: fitMode }
+
+			const video = document.createElement( 'video' );
+			video.autoplay = this.dom.dataset.previewAutoplay === 'false' ? false : true;
+			video.controls = this.dom.dataset.previewControls === 'false' ? false : true;
+			video.loop = this.dom.dataset.previewLoop === 'true' ? true : false;
+			video.muted = this.dom.dataset.previewMuted === 'true' ? true : false;
+			video.playsInline = true;
+			video.src = url;
+			contentElement.appendChild( video );
+
+			video.addEventListener( 'loadeddata', () => {
+				this.dom.dataset.state = 'loaded';
+			}, false );
+
+			video.addEventListener( 'error', () => {
+				this.dom.dataset.state = 'error';
+				contentElement.innerHTML =
+					`<span class="r-overlay-error">Unable to load video.</span>`;
+			}, false );
+
+			this.Reveal.dispatchEvent({ type: 'previewvideo', data: { url } });
+
+		}
+		else {
+			throw new Error( 'Please specify a valid media type to preview' );
+		}
+
+		this.dom.querySelector( '.r-overlay-close' ).addEventListener( 'click', ( event ) => {
+			this.close();
+			event.preventDefault();
+		}, false );
+
+	}
+
+	previewImage( url, fitMode ) {
+
+		this.previewMedia( url, 'image', fitMode );
+
+	}
+
+	previewVideo( url, fitMode ) {
+
+		this.previewMedia( url, 'video', fitMode );
+
+	}
+
+	/**
+	 * Open or close help overlay window.
+	 *
+	 * @param {Boolean} [override] Flag which overrides the
+	 * toggle logic and forcibly sets the desired state. True means
+	 * help is open, false means it's closed.
+	 */
+	toggleHelp( override ) {
+
+		if( typeof override === 'boolean' ) {
+			override ? this.showHelp() : this.close();
+		}
+		else {
+			if( this.dom ) {
+				this.close();
+			}
+			else {
+				this.showHelp();
+			}
+		}
+	}
+
+	/**
+	 * Opens an overlay window with help material.
+	 */
+	showHelp() {
+
+		if( this.Reveal.getConfig().help ) {
+
+			this.close();
+
+			this.createOverlay( 'r-overlay-help' );
+
+			let html = '<p class="title">Keyboard Shortcuts</p>';
+
+			let shortcuts = this.Reveal.keyboard.getShortcuts(),
+				bindings = this.Reveal.keyboard.getBindings();
+
+			html += '<table><th>KEY</th><th>ACTION</th>';
+			for( let key in shortcuts ) {
+				html += `<tr><td>${key}</td><td>${shortcuts[ key ]}</td></tr>`;
+			}
+
+			// Add custom key bindings that have associated descriptions
+			for( let binding in bindings ) {
+				if( bindings[binding].key && bindings[binding].description ) {
+					html += `<tr><td>${bindings[binding].key}</td><td>${bindings[binding].description}</td></tr>`;
+				}
+			}
+
+			html += '</table>';
+
+			this.viewport.innerHTML = `
+				<header class="r-overlay-header">
+					<button class="r-overlay-button r-overlay-close">Esc <span class="icon"></span></button>
+				</header>
+				<div class="r-overlay-content">
+					<div class="r-overlay-help-content">${html}</div>
+				</div>
+			`;
+
+			this.dom.querySelector( '.r-overlay-close' ).addEventListener( 'click', event => {
+				this.close();
+				event.preventDefault();
+			}, false );
+
+			this.Reveal.dispatchEvent({ type: 'showhelp' });
+
+		}
+
+	}
+
+	isOpen() {
+
+		return !!this.dom;
+
+	}
+
+	/**
+	 * Closes any currently open overlay.
+	 */
+	close() {
+
+		if( this.dom ) {
+			this.dom.remove();
+			this.dom = null;
+
+			this.state = {};
+
+			this.Reveal.dispatchEvent({ type: 'closeoverlay' });
+
+			return true;
+		}
+
+		return false;
+
+	}
+
+	getState() {
+
+		return this.state;
+
+	}
+
+	setState( state ) {
+
+		// Ignore the incoming state if none of the preview related
+		// props have changed
+		if( this.stateProps.every( key => this.state[ key ] === state[ key ] ) ) {
+			return;
+		}
+
+		if( state.previewIframe ) {
+			this.previewIframe( state.previewIframe );
+		}
+		else if( state.previewImage ) {
+			this.previewImage( state.previewImage, state.previewFit );
+		}
+		else if( state.previewVideo ) {
+			this.previewVideo( state.previewVideo, state.previewFit );
+		}
+		else {
+			this.close();
+		}
+
+	}
+
+	onSlidesClicked( event ) {
+
+		const target = event.target;
+
+		const linkTarget = target.closest( this.iframeTriggerSelector );
+		const mediaTarget = target.closest( this.mediaTriggerSelector );
+
+		// Was an iframe lightbox trigger clicked?
+		if( linkTarget ) {
+			if( event.metaKey || event.shiftKey || event.altKey ) {
+				// Let the browser handle meta keys naturally so users can cmd+click
+				return;
+			}
+			let url = linkTarget.getAttribute( 'href' ) || linkTarget.getAttribute( 'data-preview-link' );
+			if( url ) {
+				this.previewIframe( url );
+				event.preventDefault();
+			}
+		}
+		// Was a media lightbox trigger clicked?
+		else if( mediaTarget ) {
+			if( mediaTarget.hasAttribute( 'data-preview-image' ) ) {
+				let url = mediaTarget.dataset.previewImage || mediaTarget.getAttribute( 'src' );
+				if( url ) {
+					this.previewImage( url, mediaTarget.dataset.previewFit );
+					event.preventDefault();
+				}
+			}
+			else if( mediaTarget.hasAttribute( 'data-preview-video' ) ) {
+				let url = mediaTarget.dataset.previewVideo || mediaTarget.getAttribute( 'src' );
+				if( !url ) {
+					let source = mediaTarget.querySelector( 'source' );
+					if( source ) {
+						url = source.getAttribute( 'src' );
+					}
+				}
+				if( url ) {
+					this.previewVideo( url, mediaTarget.dataset.previewFit );
+					event.preventDefault();
+				}
+			}
+		}
+
+	}
+
+	destroy() {
+
+		this.close();
+
+	}
+
+}

js/controllers/scrollview.js

@@ -449,6 +449,10 @@ export default class ScrollView {
 			rangeStart = trigger.range[1];
 		} );
 
+		// Ensure the last trigger extends to the end of the page, otherwise
+		// rounding errors can cause the last trigger to end at 0.999999...
+		this.slideTriggers[this.slideTriggers.length - 1].range[1] = 1;
+
 	}
 
 	/**

js/controllers/slidecontent.js

@@ -9,11 +9,14 @@ import fitty from 'fitty';
  */
 export default class SlideContent {
 
+	allowedToPlay = true;
+
 	constructor( Reveal ) {
 
 		this.Reveal = Reveal;
 
 		this.startEmbeddedIframe = this.startEmbeddedIframe.bind( this );
+		this.ensureMobileMediaPlaying = this.ensureMobileMediaPlaying.bind( this );
 
 	}
 
@@ -51,7 +54,13 @@ export default class SlideContent {
 	load( slide, options = {} ) {
 
 		// Show the slide element
-		slide.style.display = this.Reveal.getConfig().display;
+		const displayValue = this.Reveal.getConfig().display;
+		if( displayValue.includes('!important') ) {
+			const value = displayValue.replace(/\s*!important\s*$/, '').trim();
+			slide.style.setProperty('display', value, 'important');
+		} else {
+			slide.style.display = displayValue;
+		}
 
 		// Media elements with data-src attributes
 		queryAll( slide, 'img[data-src], video[data-src], audio[data-src], iframe[data-src]' ).forEach( element => {
@@ -119,14 +128,14 @@ export default class SlideContent {
 					}
 				}
 				// Videos
-				else if ( backgroundVideo && !this.Reveal.isSpeakerNotes() ) {
+				else if ( backgroundVideo ) {
 					let video = document.createElement( 'video' );
 
 					if( backgroundVideoLoop ) {
 						video.setAttribute( 'loop', '' );
 					}
 
-					if( backgroundVideoMuted ) {
+					if( backgroundVideoMuted || this.Reveal.isSpeakerNotes() ) {
 						video.muted = true;
 					}
 
@@ -280,7 +289,9 @@ export default class SlideContent {
 	 */
 	startEmbeddedContent( element ) {
 
-		if( element && !this.Reveal.isSpeakerNotes() ) {
+		if( element ) {
+
+			const isSpeakerNotesWindow = this.Reveal.isSpeakerNotes();
 
 			// Restart GIFs
 			queryAll( element, 'img[src$=".gif"]' ).forEach( el => {
@@ -306,6 +317,9 @@ export default class SlideContent {
 
 				if( autoplay && typeof el.play === 'function' ) {
 
+					// In the speaker view we only auto-play muted media
+					if( isSpeakerNotesWindow && !el.muted ) return;
+
 					// If the media is ready, start playback
 					if( el.readyState > 1 ) {
 						this.startEmbeddedMedia( { target: el } );
@@ -315,10 +329,16 @@ export default class SlideContent {
 					else if( isMobile ) {
 						let promise = el.play();
 
+						el.addEventListener( 'canplay', this.ensureMobileMediaPlaying );
+
 						// If autoplay does not work, ensure that the controls are visible so
 						// that the viewer can start the media on their own
 						if( promise && typeof promise.catch === 'function' && el.controls === false ) {
-							promise.catch( () => {
+							promise
+							.then( () => {
+								this.allowedToPlay = true;
+							})
+							.catch( () => {
 								el.controls = true;
 
 								// Once the video does start playing, hide the controls again
@@ -337,32 +357,72 @@ export default class SlideContent {
 				}
 			} );
 
-			// Normal iframes
-			queryAll( element, 'iframe[src]' ).forEach( el => {
-				if( closest( el, '.fragment' ) && !closest( el, '.fragment.visible' ) ) {
-					return;
-				}
+			// Don't play iframe content in the speaker view since we can't
+			// guarantee that it's muted
+			if( !isSpeakerNotesWindow ) {
 
-				this.startEmbeddedIframe( { target: el } );
-			} );
+				// Normal iframes
+				queryAll( element, 'iframe[src]' ).forEach( el => {
+					if( closest( el, '.fragment' ) && !closest( el, '.fragment.visible' ) ) {
+						return;
+					}
 
-			// Lazy loading iframes
-			queryAll( element, 'iframe[data-src]' ).forEach( el => {
-				if( closest( el, '.fragment' ) && !closest( el, '.fragment.visible' ) ) {
-					return;
-				}
+					this.startEmbeddedIframe( { target: el } );
+				} );
 
-				if( el.getAttribute( 'src' ) !== el.getAttribute( 'data-src' ) ) {
-					el.removeEventListener( 'load', this.startEmbeddedIframe ); // remove first to avoid dupes
-					el.addEventListener( 'load', this.startEmbeddedIframe );
-					el.setAttribute( 'src', el.getAttribute( 'data-src' ) );
-				}
-			} );
+				// Lazy loading iframes
+				queryAll( element, 'iframe[data-src]' ).forEach( el => {
+					if( closest( el, '.fragment' ) && !closest( el, '.fragment.visible' ) ) {
+						return;
+					}
+
+					if( el.getAttribute( 'src' ) !== el.getAttribute( 'data-src' ) ) {
+						el.removeEventListener( 'load', this.startEmbeddedIframe ); // remove first to avoid dupes
+						el.addEventListener( 'load', this.startEmbeddedIframe );
+						el.setAttribute( 'src', el.getAttribute( 'data-src' ) );
+					}
+				} );
+
+			}
 
 		}
 
 	}
 
+	/**
+	 * Ensure that an HTMLMediaElement is playing on mobile devices.
+	 *
+	 * This is a workaround for a bug in mobile Safari where
+	 * the media fails to display if many videos are started
+	 * at the same moment. When this happens, Mobile Safari
+	 * reports the video is playing, and the current time
+	 * advances, but nothing is visible.
+	 *
+	 * @param {Event} event
+	 */
+	ensureMobileMediaPlaying( event ) {
+
+		const el = event.target;
+
+		// Ignore this check incompatible browsers
+		if( typeof el.getVideoPlaybackQuality !== 'function' ) {
+			return;
+		}
+
+		setTimeout( () => {
+
+			const playing = el.paused === false;
+			const totalFrames = el.getVideoPlaybackQuality().totalVideoFrames;
+
+			if( playing && totalFrames === 0 ) {
+				el.load();
+				el.play();
+			}
+
+		}, 1000 );
+
+	}
+
 	/**
 	 * Starts playing an embedded video/audio element after
 	 * it has finished loading.
@@ -375,8 +435,23 @@ export default class SlideContent {
 			isVisible  		= !!closest( event.target, '.present' );
 
 		if( isAttachedToDOM && isVisible ) {
-			event.target.currentTime = 0;
-			event.target.play();
+			// Don't restart if media is already playing
+			if( event.target.paused || event.target.ended ) {
+				event.target.currentTime = 0;
+				const promise = event.target.play();
+
+				if( promise && typeof promise.catch === 'function' ) {
+					promise
+						.then( () => {
+							this.allowedToPlay = true;
+						} )
+						.catch( ( error ) => {
+							if( error.name === 'NotAllowedError' ) {
+								this.allowedToPlay = false;
+							}
+						} );
+				}
+			}
 		}
 
 		event.target.removeEventListener( 'loadeddata', this.startEmbeddedMedia );
@@ -447,6 +522,10 @@ export default class SlideContent {
 				if( !el.hasAttribute( 'data-ignore' ) && typeof el.pause === 'function' ) {
 					el.setAttribute('data-paused-by-reveal', '');
 					el.pause();
+
+					if( isMobile ) {
+						el.removeEventListener( 'canplay', this.ensureMobileMediaPlaying );
+					}
 				}
 			} );
 
@@ -483,4 +562,15 @@ export default class SlideContent {
 
 	}
 
+	/**
+	 * Checks whether media playback is blocked by the browser. This
+	 * typically happens when media playback is initiated without a
+	 * direct user interaction.
+	 */
+	isNotAllowedToPlay() {
+
+		return !this.allowedToPlay;
+
+	}
+
 }

js/controllers/touch.js

@@ -84,7 +84,7 @@ export default class Touch {
 	isSwipePrevented( target ) {
 
 		// Prevent accidental swipes when scrubbing timelines
-		if( matches( target, 'video, audio' ) ) return true;
+		if( matches( target, 'video[controls], audio[controls]' ) ) return true;
 
 		while( target && typeof target.hasAttribute === 'function' ) {
 			if( target.hasAttribute( 'data-prevent-swipe' ) ) return true;
@@ -103,6 +103,8 @@ export default class Touch {
 	 */
 	onTouchStart( event ) {
 
+		this.touchCaptured = false;
+
 		if( this.isSwipePrevented( event.target ) ) return true;
 
 		this.touchStartX = event.touches[0].clientX;
@@ -214,6 +216,14 @@ export default class Touch {
 	 */
 	onTouchEnd( event ) {
 
+		// Media playback is only allowed as a direct result of a
+		// user interaction. Some mobile devices do not consider a
+		// 'touchmove' to be a direct user action. If this is the
+		// case, we fall back to starting playback here instead.
+		if( this.touchCaptured && this.Reveal.slideContent.isNotAllowedToPlay() ) {
+			this.Reveal.startEmbeddedContent( this.Reveal.getCurrentSlide() );
+		}
+
 		this.touchCaptured = false;
 
 	}

js/reveal.js

@@ -13,6 +13,7 @@ import Controls from './controllers/controls.js'
 import Progress from './controllers/progress.js'
 import Pointer from './controllers/pointer.js'
 import Plugins from './controllers/plugins.js'
+import Overlay from './controllers/overlay.js'
 import Touch from './controllers/touch.js'
 import Focus from './controllers/focus.js'
 import Notes from './controllers/notes.js'
@@ -28,7 +29,7 @@ import {
 } from './utils/constants.js'
 
 // The reveal.js version
-export const VERSION = '5.0.5';
+export const VERSION = '5.2.1';
 
 /**
  * reveal.js
@@ -51,6 +52,9 @@ export default function( revealElement, options ) {
 	// Configuration defaults, can be overridden at initialization time
 	let config = {},
 
+		// Flags if initialize() has been invoked for this reveal instance
+		initialized = false,
+
 		// Flags if reveal.js is loaded (has dispatched the 'ready' event)
 		ready = false,
 
@@ -116,6 +120,7 @@ export default function( revealElement, options ) {
 		progress = new Progress( Reveal ),
 		pointer = new Pointer( Reveal ),
 		plugins = new Plugins( Reveal ),
+		overlay = new Overlay( Reveal ),
 		focus = new Focus( Reveal ),
 		touch = new Touch( Reveal ),
 		notes = new Notes( Reveal );
@@ -127,6 +132,10 @@ export default function( revealElement, options ) {
 
 		if( !revealElement ) throw 'Unable to find presentation root (<div class="reveal">).';
 
+		if( initialized ) throw 'Reveal.js has already been initialized.';
+
+		initialized = true;
+
 		// Cache references to key DOM elements
 		dom.wrapper = revealElement;
 		dom.slides = revealElement.querySelector( '.slides' );
@@ -185,6 +194,9 @@ export default function( revealElement, options ) {
 	 */
 	function start() {
 
+		// Don't proceed if this instance has been destroyed
+		if( initialized === false ) return;
+
 		ready = true;
 
 		// Remove slides hidden with data-visibility
@@ -382,7 +394,7 @@ export default function( revealElement, options ) {
 
 		// Text node
 		if( node.nodeType === 3 ) {
-			text += node.textContent;
+			text += node.textContent.trim();
 		}
 		// Element node
 		else if( node.nodeType === 1 ) {
@@ -391,10 +403,25 @@ export default function( revealElement, options ) {
 			let isDisplayHidden = window.getComputedStyle( node )['display'] === 'none';
 			if( isAriaHidden !== 'true' && !isDisplayHidden ) {
 
+				// Capture alt text from img and video elements
+				if( node.tagName === 'IMG' || node.tagName === 'VIDEO' ) {
+					let altText = node.getAttribute( 'alt' );
+					if( altText ) {
+						text += ensurePunctuation( altText );
+					}
+				}
+
 				Array.from( node.childNodes ).forEach( child => {
 					text += getStatusText( child );
 				} );
 
+				// Add period after block-level text elements to improve
+				// screen reader experience
+				const textElements = ['P', 'DIV', 'UL', 'OL', 'LI', 'H1', 'H2', 'H3', 'H4', 'H5', 'H6', 'BLOCKQUOTE'];
+				if( textElements.includes( node.tagName ) && text.trim() !== '' ) {
+					text = ensurePunctuation( text );
+				}
+
 			}
 
 		}
@@ -405,6 +432,22 @@ export default function( revealElement, options ) {
 
 	}
 
+	/**
+	 * Ensures text ends with proper punctuation by adding a period
+	 * if it doesn't already end with punctuation.
+	 */
+	function ensurePunctuation( text ) {
+
+		const trimmedText = text.trim();
+
+		if( trimmedText === '' ) {
+			return text;
+		}
+
+		return !/[.!?]$/.test(trimmedText) ? trimmedText + '.' : trimmedText;
+
+	}
+
 	/**
 	 * This is an unfortunate necessity. Some actions – such as
 	 * an input field being focused in an iframe or using the
@@ -500,16 +543,6 @@ export default function( revealElement, options ) {
 			resume();
 		}
 
-		// Iframe link previews
-		if( config.previewLinks ) {
-			enablePreviewLinks();
-			disablePreviewLinks( '[data-preview-link=false]' );
-		}
-		else {
-			disablePreviewLinks();
-			enablePreviewLinks( '[data-preview-link]:not([data-preview-link=false])' );
-		}
-
 		// Reset all changes made by auto-animations
 		autoAnimate.reset();
 
@@ -604,13 +637,19 @@ export default function( revealElement, options ) {
 	 */
 	function destroy() {
 
+		initialized = false;
+
+		// There's nothing to destroy if this instance hasn't finished
+		// initializing
+		if( ready === false ) return;
+
 		removeEventListeners();
 		cancelAutoSlide();
-		disablePreviewLinks();
 
 		// Destroy controllers
 		notes.destroy();
 		focus.destroy();
+		overlay.destroy();
 		plugins.destroy();
 		pointer.destroy();
 		controls.destroy();
@@ -760,164 +799,6 @@ export default function( revealElement, options ) {
 
 	}
 
-	/**
-	 * Bind preview frame links.
-	 *
-	 * @param {string} [selector=a] - selector for anchors
-	 */
-	function enablePreviewLinks( selector = 'a' ) {
-
-		Array.from( dom.wrapper.querySelectorAll( selector ) ).forEach( element => {
-			if( /^(http|www)/gi.test( element.getAttribute( 'href' ) ) ) {
-				element.addEventListener( 'click', onPreviewLinkClicked, false );
-			}
-		} );
-
-	}
-
-	/**
-	 * Unbind preview frame links.
-	 */
-	function disablePreviewLinks( selector = 'a' ) {
-
-		Array.from( dom.wrapper.querySelectorAll( selector ) ).forEach( element => {
-			if( /^(http|www)/gi.test( element.getAttribute( 'href' ) ) ) {
-				element.removeEventListener( 'click', onPreviewLinkClicked, false );
-			}
-		} );
-
-	}
-
-	/**
-	 * Opens a preview window for the target URL.
-	 *
-	 * @param {string} url - url for preview iframe src
-	 */
-	function showPreview( url ) {
-
-		closeOverlay();
-
-		dom.overlay = document.createElement( 'div' );
-		dom.overlay.classList.add( 'overlay' );
-		dom.overlay.classList.add( 'overlay-preview' );
-		dom.wrapper.appendChild( dom.overlay );
-
-		dom.overlay.innerHTML =
-			`<header>
-				<a class="close" href="#"><span class="icon"></span></a>
-				<a class="external" href="${url}" target="_blank"><span class="icon"></span></a>
-			</header>
-			<div class="spinner"></div>
-			<div class="viewport">
-				<iframe src="${url}"></iframe>
-				<small class="viewport-inner">
-					<span class="x-frame-error">Unable to load iframe. This is likely due to the site's policy (x-frame-options).</span>
-				</small>
-			</div>`;
-
-		dom.overlay.querySelector( 'iframe' ).addEventListener( 'load', event => {
-			dom.overlay.classList.add( 'loaded' );
-		}, false );
-
-		dom.overlay.querySelector( '.close' ).addEventListener( 'click', event => {
-			closeOverlay();
-			event.preventDefault();
-		}, false );
-
-		dom.overlay.querySelector( '.external' ).addEventListener( 'click', event => {
-			closeOverlay();
-		}, false );
-
-	}
-
-	/**
-	 * Open or close help overlay window.
-	 *
-	 * @param {Boolean} [override] Flag which overrides the
-	 * toggle logic and forcibly sets the desired state. True means
-	 * help is open, false means it's closed.
-	 */
-	function toggleHelp( override ){
-
-		if( typeof override === 'boolean' ) {
-			override ? showHelp() : closeOverlay();
-		}
-		else {
-			if( dom.overlay ) {
-				closeOverlay();
-			}
-			else {
-				showHelp();
-			}
-		}
-	}
-
-	/**
-	 * Opens an overlay window with help material.
-	 */
-	function showHelp() {
-
-		if( config.help ) {
-
-			closeOverlay();
-
-			dom.overlay = document.createElement( 'div' );
-			dom.overlay.classList.add( 'overlay' );
-			dom.overlay.classList.add( 'overlay-help' );
-			dom.wrapper.appendChild( dom.overlay );
-
-			let html = '<p class="title">Keyboard Shortcuts</p><br/>';
-
-			let shortcuts = keyboard.getShortcuts(),
-				bindings = keyboard.getBindings();
-
-			html += '<table><th>KEY</th><th>ACTION</th>';
-			for( let key in shortcuts ) {
-				html += `<tr><td>${key}</td><td>${shortcuts[ key ]}</td></tr>`;
-			}
-
-			// Add custom key bindings that have associated descriptions
-			for( let binding in bindings ) {
-				if( bindings[binding].key && bindings[binding].description ) {
-					html += `<tr><td>${bindings[binding].key}</td><td>${bindings[binding].description}</td></tr>`;
-				}
-			}
-
-			html += '</table>';
-
-			dom.overlay.innerHTML = `
-				<header>
-					<a class="close" href="#"><span class="icon"></span></a>
-				</header>
-				<div class="viewport">
-					<div class="viewport-inner">${html}</div>
-				</div>
-			`;
-
-			dom.overlay.querySelector( '.close' ).addEventListener( 'click', event => {
-				closeOverlay();
-				event.preventDefault();
-			}, false );
-
-		}
-
-	}
-
-	/**
-	 * Closes any currently open overlay.
-	 */
-	function closeOverlay() {
-
-		if( dom.overlay ) {
-			dom.overlay.parentNode.removeChild( dom.overlay );
-			dom.overlay = null;
-			return true;
-		}
-
-		return false;
-
-	}
-
 	/**
 	 * Applies JavaScript-controlled layout rules to the
 	 * presentation.
@@ -1243,7 +1124,7 @@ export default function( revealElement, options ) {
 
 	/**
 	 * Returns true if we're currently on the last slide in
-	 * the presenation. If the last slide is a stack, we only
+	 * the presentation. If the last slide is a stack, we only
 	 * consider this the last slide if it's at the end of the
 	 * stack.
 	 */
@@ -1446,6 +1327,9 @@ export default function( revealElement, options ) {
 		let currentHorizontalSlide = horizontalSlides[ indexh ],
 			currentVerticalSlides = currentHorizontalSlide.querySelectorAll( 'section' );
 
+		// Indicate when we're on a vertical slide
+		revealElement.classList.toggle( 'is-vertical-slide', currentVerticalSlides.length > 1 );
+
 		// Store references to the previous and current slides
 		currentSlide = currentVerticalSlides[ indexv ] || currentHorizontalSlide;
 
@@ -1671,6 +1555,7 @@ export default function( revealElement, options ) {
 
 		notes.update();
 		notes.updateVisibility();
+		overlay.update();
 		backgrounds.update( true );
 		slideNumber.update();
 		slideContent.formatEmbeddedContent();
@@ -1928,14 +1813,16 @@ export default function( revealElement, options ) {
 
 		if( horizontalSlidesLength && typeof indexh !== 'undefined' ) {
 
+			const isOverview = overview.isActive();
+
 			// The number of steps away from the present slide that will
 			// be visible
-			let viewDistance = overview.isActive() ? 10 : config.viewDistance;
+			let viewDistance = isOverview ? 10 : config.viewDistance;
 
 			// Shorten the view distance on devices that typically have
 			// less resources
 			if( Device.isMobile ) {
-				viewDistance = overview.isActive() ? 6 : config.mobileViewDistance;
+				viewDistance = isOverview ? 6 : config.mobileViewDistance;
 			}
 
 			// All slides need to be visible when exporting to PDF
@@ -1968,7 +1855,7 @@ export default function( revealElement, options ) {
 
 				if( verticalSlidesLength ) {
 
-					let oy = getPreviousVerticalIndex( horizontalSlide );
+					let oy = isOverview ? 0 : getPreviousVerticalIndex( horizontalSlide );
 
 					for( let y = 0; y < verticalSlidesLength; y++ ) {
 						let verticalSlide = verticalSlides[y];
@@ -2356,7 +2243,8 @@ export default function( revealElement, options ) {
 			indexv: indices.v,
 			indexf: indices.f,
 			paused: isPaused(),
-			overview: overview.isActive()
+			overview: overview.isActive(),
+			...overlay.getState()
 		};
 
 	}
@@ -2382,6 +2270,8 @@ export default function( revealElement, options ) {
 			if( typeof overviewFlag === 'boolean' && overviewFlag !== overview.isActive() ) {
 				overview.toggle( overviewFlag );
 			}
+
+			overlay.setState( state );
 		}
 
 	}
@@ -2595,6 +2485,9 @@ export default function( revealElement, options ) {
 					let h = indexh - 1;
 					slide( h, v );
 				}
+				else if( config.rtl ) {
+					navigateRight({skipFragments});
+				}
 				else {
 					navigateLeft({skipFragments});
 				}
@@ -2783,24 +2676,6 @@ export default function( revealElement, options ) {
 
 	}
 
-	/**
-	 * Handles clicks on links that are set to preview in the
-	 * iframe overlay.
-	 *
-	 * @param {object} event
-	 */
-	function onPreviewLinkClicked( event ) {
-
-		if( event.currentTarget && event.currentTarget.hasAttribute( 'href' ) ) {
-			let url = event.currentTarget.getAttribute( 'href' );
-			if( url ) {
-				showPreview( url );
-				event.preventDefault();
-			}
-		}
-
-	}
-
 	/**
 	 * Handles click on the auto-sliding controls element.
 	 *
@@ -2879,7 +2754,7 @@ export default function( revealElement, options ) {
 		availableFragments: fragments.availableRoutes.bind( fragments ),
 
 		// Toggles a help overlay with keyboard shortcuts
-		toggleHelp,
+		toggleHelp: overlay.toggleHelp.bind( overlay ),
 
 		// Toggles the overview mode on/off
 		toggleOverview: overview.toggle.bind( overview ),
@@ -2909,7 +2784,7 @@ export default function( revealElement, options ) {
 		isSpeakerNotes: notes.isSpeakerNotesWindow.bind( notes ),
 		isOverview: overview.isActive.bind( overview ),
 		isFocused: focus.isFocused.bind( focus ),
-
+		isOverlayOpen: overlay.isOpen.bind( overlay ),
 		isScrollView: scrollView.isActive.bind( scrollView ),
 		isPrintView: printView.isActive.bind( printView ),
 
@@ -2920,13 +2795,17 @@ export default function( revealElement, options ) {
 		loadSlide: slideContent.load.bind( slideContent ),
 		unloadSlide: slideContent.unload.bind( slideContent ),
 
-		// Media playback
+		// Start/stop all media inside of the current slide
 		startEmbeddedContent: () => slideContent.startEmbeddedContent( currentSlide ),
 		stopEmbeddedContent: () => slideContent.stopEmbeddedContent( currentSlide, { unloadIframes: false } ),
 
-		// Preview management
-		showPreview,
-		hidePreview: closeOverlay,
+		// Lightbox previews
+		previewIframe: overlay.previewIframe.bind( overlay ),
+		previewImage: overlay.previewImage.bind( overlay ),
+		previewVideo: overlay.previewVideo.bind( overlay ),
+
+		showPreview: overlay.previewIframe.bind( overlay ), // deprecated in favor of showIframeLightbox
+		hidePreview: overlay.close.bind( overlay ),
 
 		// Adds or removes all internal event listeners
 		addEventListeners,
@@ -3040,13 +2919,14 @@ export default function( revealElement, options ) {
 		controls,
 		location,
 		overview,
+		keyboard,
 		fragments,
 		backgrounds,
 		slideContent,
 		slideNumber,
 
 		onUserInput,
-		closeOverlay,
+		closeOverlay: overlay.close.bind( overlay ),
 		updateSlidesVisibility,
 		layoutSlideContents,
 		transformSlides,

js/utils/color.js

@@ -44,7 +44,7 @@ export const colorToRgb = ( color ) => {
 		};
 	}
 
-	let rgba = color.match( /^rgba\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*\,\s*([\d]+|[\d]*.[\d]+)\s*\)$/i );
+	let rgba = color.match( /^rgba\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*,\s*([\d]+|[\d]*.[\d]+)\s*\)$/i );
 	if( rgba ) {
 		return {
 			r: parseInt( rgba[1], 10 ),

package.json

@@ -1,6 +1,6 @@
 {
   "name": "reveal.js",
-  "version": "5.0.5",
+  "version": "5.2.1",
   "description": "The HTML Presentation Framework",
   "homepage": "https://revealjs.com",
   "subdomain": "revealjs",
@@ -42,25 +42,29 @@
     "core-js": "^3.33.1",
     "fitty": "^2.3.7",
     "glob": "^10.3.10",
-    "gulp": "^4.0.2",
+    "gulp": "^5.0.0",
     "gulp-autoprefixer": "^8.0.0",
     "gulp-clean-css": "^4.3.0",
     "gulp-connect": "^5.7.0",
     "gulp-eslint": "^6.0.0",
-    "gulp-header": "^2.0.9",
-    "gulp-tap": "^2.0.0",
+    "gulp-header-comment": "^0.10.0",
     "gulp-zip": "^5.1.0",
     "highlight.js": "^11.9.0",
     "marked": "^4.3.0",
-    "node-qunit-puppeteer": "^2.1.2",
-    "qunit": "^2.20.0",
+    "node-qunit-puppeteer": "^2.2.0",
+    "through2": "^4.0.2",
+    "qunit": "^2.22.0",
     "rollup": "^4.1.5",
-    "sass": "^1.69.5",
+    "sass": "^1.79.4",
     "yargs": "^17.7.2"
   },
   "overrides": {
-    "chokidar": "3.5.3",
-    "glob-parent": "6.0.2"
+    "gulp-connect": {
+      "send": "0.19.0"
+    },
+    "gulp-header-comment": {
+      "moment": "2.30.1"
+    }
   },
   "browserslist": "> 2%, not dead",
   "eslintConfig": {

plugin/highlight/plugin.js

@@ -52,7 +52,7 @@ const Plugin = {
 				block.innerHTML = betterTrim( block );
 			}
 
-			// Escape HTML tags unless the "data-noescape" attrbute is present
+			// Escape HTML tags unless the "data-noescape" attribute is present
 			if( config.escapeHTML && !block.hasAttribute( 'data-noescape' )) {
 				block.innerHTML = block.innerHTML.replace( /</g,"&lt;").replace(/>/g, '&gt;' );
 			}

plugin/math/katex.js

@@ -16,7 +16,7 @@ export const KaTeX = () => {
 			{left: '\\(', right: '\\)', display: false},
 			{left: '\\[', right: '\\]', display: true}
 		],
-		ignoredTags: ['script', 'noscript', 'style', 'textarea', 'pre']
+		ignoredTags: ['script', 'noscript', 'style', 'textarea', 'pre', 'code']
 	}
 
 	const loadCss = src => {

plugin/math/math.esm.js

@@ -1,6 +1,6 @@
-const t=()=>{let t,e={messageStyle:"none",tex2jax:{inlineMath:[["$","$"],["\\(","\\)"]],skipTags:["script","noscript","style","textarea","pre"]},skipStartupTypeset:!0};return{id:"mathjax2",init:function(a){t=a;let n=t.getConfig().mathjax2||t.getConfig().math||{},i={...e,...n},s=(i.mathjax||"https://cdn.jsdelivr.net/npm/mathjax@2/MathJax.js")+"?config="+(i.config||"TeX-AMS_HTML-full");i.tex2jax={...e.tex2jax,...n.tex2jax},i.mathjax=i.config=null,function(t,e){let a=document.querySelector("head"),n=document.createElement("script");n.type="text/javascript",n.src=t;let i=()=>{"function"==typeof e&&(e.call(),e=null)};n.onload=i,n.onreadystatechange=()=>{"loaded"===this.readyState&&i()},a.appendChild(n)}(s,(function(){MathJax.Hub.Config(i),MathJax.Hub.Queue(["Typeset",MathJax.Hub,t.getRevealElement()]),MathJax.Hub.Queue(t.layout),t.on("slidechanged",(function(t){MathJax.Hub.Queue(["Typeset",MathJax.Hub,t.currentSlide])}))}))}}},e=t;
+const t=()=>{let t,e={messageStyle:"none",tex2jax:{inlineMath:[["$","$"],["\\(","\\)"]],skipTags:["script","noscript","style","textarea","pre","code"]},skipStartupTypeset:!0};return{id:"mathjax2",init:function(a){t=a;let n=t.getConfig().mathjax2||t.getConfig().math||{},i={...e,...n},s=(i.mathjax||"https://cdn.jsdelivr.net/npm/mathjax@2/MathJax.js")+"?config="+(i.config||"TeX-AMS_HTML-full");i.tex2jax={...e.tex2jax,...n.tex2jax},i.mathjax=i.config=null,function(t,e){let a=document.querySelector("head"),n=document.createElement("script");n.type="text/javascript",n.src=t;let i=()=>{"function"==typeof e&&(e.call(),e=null)};n.onload=i,n.onreadystatechange=()=>{"loaded"===this.readyState&&i()},a.appendChild(n)}(s,(function(){MathJax.Hub.Config(i),MathJax.Hub.Queue(["Typeset",MathJax.Hub,t.getRevealElement()]),MathJax.Hub.Queue(t.layout),t.on("slidechanged",(function(t){MathJax.Hub.Queue(["Typeset",MathJax.Hub,t.currentSlide])}))}))}}},e=t;
 /*!
  * This plugin is a wrapper for the MathJax2,
  * MathJax3 and KaTeX typesetter plugins.
  */
-var a=Plugin=Object.assign(e(),{KaTeX:()=>{let t,e={version:"latest",delimiters:[{left:"$$",right:"$$",display:!0},{left:"$",right:"$",display:!1},{left:"\\(",right:"\\)",display:!1},{left:"\\[",right:"\\]",display:!0}],ignoredTags:["script","noscript","style","textarea","pre"]};const a=t=>new Promise(((e,a)=>{const n=document.createElement("script");n.type="text/javascript",n.onload=e,n.onerror=a,n.src=t,document.head.append(n)}));return{id:"katex",init:function(n){t=n;let i=t.getConfig().katex||{},s={...e,...i};const{local:l,version:o,extensions:r,...c}=s;let d=s.local||"https://cdn.jsdelivr.net/npm/katex",p=s.local?"":"@"+s.version,u=d+p+"/dist/katex.min.css",h=d+p+"/dist/contrib/mhchem.min.js",x=d+p+"/dist/contrib/auto-render.min.js",m=[d+p+"/dist/katex.min.js"];s.extensions&&s.extensions.includes("mhchem")&&m.push(h),m.push(x);const f=()=>{renderMathInElement(n.getSlidesElement(),c),t.layout()};(t=>{let e=document.createElement("link");e.rel="stylesheet",e.href=t,document.head.appendChild(e)})(u),async function(t){for(const e of t)await a(e)}(m).then((()=>{t.isReady()?f():t.on("ready",f.bind(this))}))}}},MathJax2:t,MathJax3:()=>{let t,e={tex:{inlineMath:[["$","$"],["\\(","\\)"]]},options:{skipHtmlTags:["script","noscript","style","textarea","pre"]},startup:{ready:()=>{MathJax.startup.defaultReady(),MathJax.startup.promise.then((()=>{Reveal.layout()}))}}};return{id:"mathjax3",init:function(a){t=a;let n=t.getConfig().mathjax3||{},i={...e,...n};i.tex={...e.tex,...n.tex},i.options={...e.options,...n.options},i.startup={...e.startup,...n.startup};let s=i.mathjax||"https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js";i.mathjax=null,window.MathJax=i,function(t,e){let a=document.createElement("script");a.type="text/javascript",a.id="MathJax-script",a.src=t,a.async=!0,a.onload=()=>{"function"==typeof e&&(e.call(),e=null)},document.head.appendChild(a)}(s,(function(){Reveal.addEventListener("slidechanged",(function(t){MathJax.typeset()}))}))}}}});export{a as default};
+var a=Plugin=Object.assign(e(),{KaTeX:()=>{let t,e={version:"latest",delimiters:[{left:"$$",right:"$$",display:!0},{left:"$",right:"$",display:!1},{left:"\\(",right:"\\)",display:!1},{left:"\\[",right:"\\]",display:!0}],ignoredTags:["script","noscript","style","textarea","pre","code"]};const a=t=>new Promise(((e,a)=>{const n=document.createElement("script");n.type="text/javascript",n.onload=e,n.onerror=a,n.src=t,document.head.append(n)}));return{id:"katex",init:function(n){t=n;let i=t.getConfig().katex||{},s={...e,...i};const{local:o,version:l,extensions:r,...c}=s;let d=s.local||"https://cdn.jsdelivr.net/npm/katex",p=s.local?"":"@"+s.version,u=d+p+"/dist/katex.min.css",h=d+p+"/dist/contrib/mhchem.min.js",x=d+p+"/dist/contrib/auto-render.min.js",m=[d+p+"/dist/katex.min.js"];s.extensions&&s.extensions.includes("mhchem")&&m.push(h),m.push(x);const f=()=>{renderMathInElement(n.getSlidesElement(),c),t.layout()};(t=>{let e=document.createElement("link");e.rel="stylesheet",e.href=t,document.head.appendChild(e)})(u),async function(t){for(const e of t)await a(e)}(m).then((()=>{t.isReady()?f():t.on("ready",f.bind(this))}))}}},MathJax2:t,MathJax3:()=>{let t,e={tex:{inlineMath:[["$","$"],["\\(","\\)"]]},options:{skipHtmlTags:["script","noscript","style","textarea","pre","code"]},startup:{ready:()=>{MathJax.startup.defaultReady(),MathJax.startup.promise.then((()=>{t.layout()}))}}};return{id:"mathjax3",init:function(a){t=a;let n=t.getConfig().mathjax3||{},i={...e,...n};i.tex={...e.tex,...n.tex},i.options={...e.options,...n.options},i.startup={...e.startup,...n.startup};let s=i.mathjax||"https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js";i.mathjax=null,window.MathJax=i,function(t,e){let a=document.createElement("script");a.type="text/javascript",a.id="MathJax-script",a.src=t,a.async=!0,a.onload=()=>{"function"==typeof e&&(e.call(),e=null)},document.head.appendChild(a)}(s,(function(){t.addEventListener("slidechanged",(function(t){MathJax.typeset()}))}))}}}});export{a as default};

plugin/math/math.js

@@ -1 +1 @@
-!function(t,e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define(e):(t="undefined"!=typeof globalThis?globalThis:t||self).RevealMath=e()}(this,(function(){"use strict";const t=()=>{let t,e={messageStyle:"none",tex2jax:{inlineMath:[["$","$"],["\\(","\\)"]],skipTags:["script","noscript","style","textarea","pre"]},skipStartupTypeset:!0};return{id:"mathjax2",init:function(n){t=n;let a=t.getConfig().mathjax2||t.getConfig().math||{},i={...e,...a},s=(i.mathjax||"https://cdn.jsdelivr.net/npm/mathjax@2/MathJax.js")+"?config="+(i.config||"TeX-AMS_HTML-full");i.tex2jax={...e.tex2jax,...a.tex2jax},i.mathjax=i.config=null,function(t,e){let n=document.querySelector("head"),a=document.createElement("script");a.type="text/javascript",a.src=t;let i=()=>{"function"==typeof e&&(e.call(),e=null)};a.onload=i,a.onreadystatechange=()=>{"loaded"===this.readyState&&i()},n.appendChild(a)}(s,(function(){MathJax.Hub.Config(i),MathJax.Hub.Queue(["Typeset",MathJax.Hub,t.getRevealElement()]),MathJax.Hub.Queue(t.layout),t.on("slidechanged",(function(t){MathJax.Hub.Queue(["Typeset",MathJax.Hub,t.currentSlide])}))}))}}},e=t;return Plugin=Object.assign(e(),{KaTeX:()=>{let t,e={version:"latest",delimiters:[{left:"$$",right:"$$",display:!0},{left:"$",right:"$",display:!1},{left:"\\(",right:"\\)",display:!1},{left:"\\[",right:"\\]",display:!0}],ignoredTags:["script","noscript","style","textarea","pre"]};const n=t=>new Promise(((e,n)=>{const a=document.createElement("script");a.type="text/javascript",a.onload=e,a.onerror=n,a.src=t,document.head.append(a)}));return{id:"katex",init:function(a){t=a;let i=t.getConfig().katex||{},s={...e,...i};const{local:o,version:l,extensions:r,...c}=s;let d=s.local||"https://cdn.jsdelivr.net/npm/katex",u=s.local?"":"@"+s.version,p=d+u+"/dist/katex.min.css",h=d+u+"/dist/contrib/mhchem.min.js",x=d+u+"/dist/contrib/auto-render.min.js",m=[d+u+"/dist/katex.min.js"];s.extensions&&s.extensions.includes("mhchem")&&m.push(h),m.push(x);const f=()=>{renderMathInElement(a.getSlidesElement(),c),t.layout()};(t=>{let e=document.createElement("link");e.rel="stylesheet",e.href=t,document.head.appendChild(e)})(p),async function(t){for(const e of t)await n(e)}(m).then((()=>{t.isReady()?f():t.on("ready",f.bind(this))}))}}},MathJax2:t,MathJax3:()=>{let t,e={tex:{inlineMath:[["$","$"],["\\(","\\)"]]},options:{skipHtmlTags:["script","noscript","style","textarea","pre"]},startup:{ready:()=>{MathJax.startup.defaultReady(),MathJax.startup.promise.then((()=>{Reveal.layout()}))}}};return{id:"mathjax3",init:function(n){t=n;let a=t.getConfig().mathjax3||{},i={...e,...a};i.tex={...e.tex,...a.tex},i.options={...e.options,...a.options},i.startup={...e.startup,...a.startup};let s=i.mathjax||"https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js";i.mathjax=null,window.MathJax=i,function(t,e){let n=document.createElement("script");n.type="text/javascript",n.id="MathJax-script",n.src=t,n.async=!0,n.onload=()=>{"function"==typeof e&&(e.call(),e=null)},document.head.appendChild(n)}(s,(function(){Reveal.addEventListener("slidechanged",(function(t){MathJax.typeset()}))}))}}}})}));
+!function(t,e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define(e):(t="undefined"!=typeof globalThis?globalThis:t||self).RevealMath=e()}(this,(function(){"use strict";const t=()=>{let t,e={messageStyle:"none",tex2jax:{inlineMath:[["$","$"],["\\(","\\)"]],skipTags:["script","noscript","style","textarea","pre","code"]},skipStartupTypeset:!0};return{id:"mathjax2",init:function(n){t=n;let a=t.getConfig().mathjax2||t.getConfig().math||{},i={...e,...a},s=(i.mathjax||"https://cdn.jsdelivr.net/npm/mathjax@2/MathJax.js")+"?config="+(i.config||"TeX-AMS_HTML-full");i.tex2jax={...e.tex2jax,...a.tex2jax},i.mathjax=i.config=null,function(t,e){let n=document.querySelector("head"),a=document.createElement("script");a.type="text/javascript",a.src=t;let i=()=>{"function"==typeof e&&(e.call(),e=null)};a.onload=i,a.onreadystatechange=()=>{"loaded"===this.readyState&&i()},n.appendChild(a)}(s,(function(){MathJax.Hub.Config(i),MathJax.Hub.Queue(["Typeset",MathJax.Hub,t.getRevealElement()]),MathJax.Hub.Queue(t.layout),t.on("slidechanged",(function(t){MathJax.Hub.Queue(["Typeset",MathJax.Hub,t.currentSlide])}))}))}}},e=t;return Plugin=Object.assign(e(),{KaTeX:()=>{let t,e={version:"latest",delimiters:[{left:"$$",right:"$$",display:!0},{left:"$",right:"$",display:!1},{left:"\\(",right:"\\)",display:!1},{left:"\\[",right:"\\]",display:!0}],ignoredTags:["script","noscript","style","textarea","pre","code"]};const n=t=>new Promise(((e,n)=>{const a=document.createElement("script");a.type="text/javascript",a.onload=e,a.onerror=n,a.src=t,document.head.append(a)}));return{id:"katex",init:function(a){t=a;let i=t.getConfig().katex||{},s={...e,...i};const{local:o,version:l,extensions:c,...r}=s;let d=s.local||"https://cdn.jsdelivr.net/npm/katex",u=s.local?"":"@"+s.version,p=d+u+"/dist/katex.min.css",h=d+u+"/dist/contrib/mhchem.min.js",x=d+u+"/dist/contrib/auto-render.min.js",m=[d+u+"/dist/katex.min.js"];s.extensions&&s.extensions.includes("mhchem")&&m.push(h),m.push(x);const f=()=>{renderMathInElement(a.getSlidesElement(),r),t.layout()};(t=>{let e=document.createElement("link");e.rel="stylesheet",e.href=t,document.head.appendChild(e)})(p),async function(t){for(const e of t)await n(e)}(m).then((()=>{t.isReady()?f():t.on("ready",f.bind(this))}))}}},MathJax2:t,MathJax3:()=>{let t,e={tex:{inlineMath:[["$","$"],["\\(","\\)"]]},options:{skipHtmlTags:["script","noscript","style","textarea","pre","code"]},startup:{ready:()=>{MathJax.startup.defaultReady(),MathJax.startup.promise.then((()=>{t.layout()}))}}};return{id:"mathjax3",init:function(n){t=n;let a=t.getConfig().mathjax3||{},i={...e,...a};i.tex={...e.tex,...a.tex},i.options={...e.options,...a.options},i.startup={...e.startup,...a.startup};let s=i.mathjax||"https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js";i.mathjax=null,window.MathJax=i,function(t,e){let n=document.createElement("script");n.type="text/javascript",n.id="MathJax-script",n.src=t,n.async=!0,n.onload=()=>{"function"==typeof e&&(e.call(),e=null)},document.head.appendChild(n)}(s,(function(){t.addEventListener("slidechanged",(function(t){MathJax.typeset()}))}))}}}})}));

plugin/math/mathjax2.js

@@ -13,7 +13,7 @@ export const MathJax2 = () => {
 		messageStyle: 'none',
 		tex2jax: {
 			inlineMath: [ [ '$', '$' ], [ '\\(', '\\)' ] ],
-			skipTags: [ 'script', 'noscript', 'style', 'textarea', 'pre' ]
+			skipTags: [ 'script', 'noscript', 'style', 'textarea', 'pre', 'code' ]
 		},
 		skipStartupTypeset: true
 	};

plugin/math/mathjax3.js

@@ -15,13 +15,13 @@ export const MathJax3 = () => {
             inlineMath: [ [ '$', '$' ], [ '\\(', '\\)' ]  ]
         },
         options: {
-            skipHtmlTags: [ 'script', 'noscript', 'style', 'textarea', 'pre' ]
+            skipHtmlTags: [ 'script', 'noscript', 'style', 'textarea', 'pre', 'code' ]
         },
         startup: {
             ready: () => {
                 MathJax.startup.defaultReady();
                 MathJax.startup.promise.then(() => {
-                    Reveal.layout();
+                    deck.layout();
                 });
             }
         }
@@ -66,7 +66,7 @@ export const MathJax3 = () => {
 
             loadScript( url, function() {
                 // Reprocess equations in slides when they turn visible
-                Reveal.addEventListener( 'slidechanged', function( event ) {
+                deck.addEventListener( 'slidechanged', function( event ) {
                     MathJax.typeset();
                 } );
             } );

plugin/notes/plugin.js

@@ -180,14 +180,16 @@ const Plugin = () => {
 		// (added 12/5/22 as a XSS safeguard)
 		if( isSameOriginEvent( event ) ) {
 
-			let data = JSON.parse( event.data );
-			if( data && data.namespace === 'reveal-notes' && data.type === 'connected' ) {
-				clearInterval( connectInterval );
-				onConnected();
-			}
-			else if( data && data.namespace === 'reveal-notes' && data.type === 'call' ) {
-				callRevealApi( data.methodName, data.arguments, data.callId );
-			}
+			try {
+				let data = JSON.parse( event.data );
+				if( data && data.namespace === 'reveal-notes' && data.type === 'connected' ) {
+					clearInterval( connectInterval );
+					onConnected();
+				}
+				else if( data && data.namespace === 'reveal-notes' && data.type === 'call' ) {
+					callRevealApi( data.methodName, data.arguments, data.callId );
+				}
+		  } catch (e) {}
 
 		}
 
@@ -207,6 +209,10 @@ const Plugin = () => {
 		deck.on( 'overviewshown', post );
 		deck.on( 'paused', post );
 		deck.on( 'resumed', post );
+		deck.on( 'previewiframe', post );
+		deck.on( 'previewimage', post );
+		deck.on( 'previewvideo', post );
+		deck.on( 'closeoverlay', post );
 
 		// Post the initial state
 		post();
@@ -227,7 +233,7 @@ const Plugin = () => {
 					openSpeakerWindow();
 				}
 				else {
-					// Keep listening for speaker view hearbeats. If we receive a
+					// Keep listening for speaker view heartbeats. If we receive a
 					// heartbeat from an orphaned window, reconnect it. This ensures
 					// that we remain connected to the notes even if the presentation
 					// is reloaded.

plugin/notes/speaker-view.html

@@ -414,14 +414,24 @@
 					}
 					// Messages sent by the reveal.js inside of the current slide preview
 					else if( data && data.namespace === 'reveal' ) {
+						const supportedEvents = [
+							'slidechanged',
+							'fragmentshown',
+							'fragmenthidden',
+							'paused',
+							'resumed',
+							'previewiframe',
+							'previewimage',
+							'previewvideo',
+							'closeoverlay'
+						];
+
 						if( /ready/.test( data.eventName ) ) {
 							// Send a message back to notify that the handshake is complete
 							window.opener.postMessage( JSON.stringify({ namespace: 'reveal-notes', type: 'connected'} ), '*' );
 						}
-						else if( /slidechanged|fragmentshown|fragmenthidden|paused|resumed/.test( data.eventName ) && currentState !== JSON.stringify( data.state ) ) {
-
+						else if( supportedEvents.includes( data.eventName ) && currentState !== JSON.stringify( data.state ) ) {
 							dispatchStateToMainWindow( data.state );
-
 						}
 					}
 
@@ -494,9 +504,12 @@
 						notes.classList.add( 'hidden' );
 					}
 
+					// Don't show lightboxes in the upcoming slide
+					const { previewVideo, previewImage, previewIframe, ...upcomingState } = data.state;
+
 					// Update the note slides
 					currentSlide.contentWindow.postMessage( JSON.stringify({ method: 'setState', args: [ data.state ] }), '*' );
-					upcomingSlide.contentWindow.postMessage( JSON.stringify({ method: 'setState', args: [ data.state ] }), '*' );
+					upcomingSlide.contentWindow.postMessage( JSON.stringify({ method: 'setState', args: [ upcomingState ] }), '*' );
 					upcomingSlide.contentWindow.postMessage( JSON.stringify({ method: 'next' }), '*' );
 
 				}

plugin/search/plugin.js

@@ -235,7 +235,9 @@ const Plugin = () => {
 
 		},
 
-		open: openSearch
+		open: openSearch,
+		close: closeSearch,
+		toggle: toggleSearch
 
 	}
 };

plugin/search/search.esm.js

@@ -4,4 +4,4 @@
  *
  * @author Jon Snyder <snyder.jon@gmail.com>, February 2013
  */
-const e=()=>{let e,t,n,l,i,o,r;function s(){t=document.createElement("div"),t.classList.add("searchbox"),t.style.position="absolute",t.style.top="10px",t.style.right="10px",t.style.zIndex=10,t.innerHTML='<input type="search" class="searchinput" placeholder="Search..." style="vertical-align: top;"/>\n\t\t</span>',n=t.querySelector(".searchinput"),n.style.width="240px",n.style.fontSize="14px",n.style.padding="4px 6px",n.style.color="#000",n.style.background="#fff",n.style.borderRadius="2px",n.style.border="0",n.style.outline="0",n.style.boxShadow="0 2px 18px rgba(0, 0, 0, 0.2)",n.style["-webkit-appearance"]="none",e.getRevealElement().appendChild(t),n.addEventListener("keyup",(function(t){if(13===t.keyCode)t.preventDefault(),function(){if(o){var t=n.value;""===t?(r&&r.remove(),l=null):(r=new c("slidecontent"),l=r.apply(t),i=0)}l&&(l.length&&l.length<=i&&(i=0),l.length>i&&(e.slide(l[i].h,l[i].v),i++))}(),o=!1;else o=!0}),!1),d()}function a(){t||s(),t.style.display="inline",n.focus(),n.select()}function d(){t||s(),t.style.display="none",r&&r.remove()}function c(t,n){var l=document.getElementById(t)||document.body,i=n||"EM",o=new RegExp("^(?:"+i+"|SCRIPT|FORM)$"),r=["#ff6","#a0ffff","#9f9","#f99","#f6f"],s=[],a=0,d="",c=[];this.setRegex=function(e){e=e.trim(),d=new RegExp("("+e+")","i")},this.getRegex=function(){return d.toString().replace(/^\/\\b\(|\)\\b\/i$/g,"").replace(/\|/g," ")},this.hiliteWords=function(t){if(null!=t&&t&&d&&!o.test(t.nodeName)){if(t.hasChildNodes())for(var n=0;n<t.childNodes.length;n++)this.hiliteWords(t.childNodes[n]);var l,p;if(3==t.nodeType)if((l=t.nodeValue)&&(p=d.exec(l))){for(var u=t;null!=u&&"SECTION"!=u.nodeName;)u=u.parentNode;var h=e.getIndices(u),f=c.length,y=!1;for(n=0;n<f;n++)c[n].h===h.h&&c[n].v===h.v&&(y=!0);y||c.push(h),s[p[0].toLowerCase()]||(s[p[0].toLowerCase()]=r[a++%r.length]);var g=document.createElement(i);g.appendChild(document.createTextNode(p[0])),g.style.backgroundColor=s[p[0].toLowerCase()],g.style.fontStyle="inherit",g.style.color="#000";var v=t.splitText(p.index);v.nodeValue=v.nodeValue.substring(p[0].length),t.parentNode.insertBefore(g,v)}}},this.remove=function(){for(var e,t=document.getElementsByTagName(i);t.length&&(e=t[0]);)e.parentNode.replaceChild(e.firstChild,e)},this.apply=function(e){if(null!=e&&e)return this.remove(),this.setRegex(e),this.hiliteWords(l),c}}return{id:"search",init:n=>{e=n,e.registerKeyboardShortcut("CTRL + Shift + F","Search"),document.addEventListener("keydown",(function(e){"F"==e.key&&(e.ctrlKey||e.metaKey)&&(e.preventDefault(),t||s(),"inline"!==t.style.display?a():d())}),!1)},open:a}};export{e as default};
+const e=()=>{let e,t,n,l,o,i,r;function s(){t=document.createElement("div"),t.classList.add("searchbox"),t.style.position="absolute",t.style.top="10px",t.style.right="10px",t.style.zIndex=10,t.innerHTML='<input type="search" class="searchinput" placeholder="Search..." style="vertical-align: top;"/>\n\t\t</span>',n=t.querySelector(".searchinput"),n.style.width="240px",n.style.fontSize="14px",n.style.padding="4px 6px",n.style.color="#000",n.style.background="#fff",n.style.borderRadius="2px",n.style.border="0",n.style.outline="0",n.style.boxShadow="0 2px 18px rgba(0, 0, 0, 0.2)",n.style["-webkit-appearance"]="none",e.getRevealElement().appendChild(t),n.addEventListener("keyup",(function(t){if(13===t.keyCode)t.preventDefault(),function(){if(i){var t=n.value;""===t?(r&&r.remove(),l=null):(r=new p("slidecontent"),l=r.apply(t),o=0)}l&&(l.length&&l.length<=o&&(o=0),l.length>o&&(e.slide(l[o].h,l[o].v),o++))}(),i=!1;else i=!0}),!1),d()}function a(){t||s(),t.style.display="inline",n.focus(),n.select()}function d(){t||s(),t.style.display="none",r&&r.remove()}function c(){t||s(),"inline"!==t.style.display?a():d()}function p(t,n){var l=document.getElementById(t)||document.body,o=n||"EM",i=new RegExp("^(?:"+o+"|SCRIPT|FORM)$"),r=["#ff6","#a0ffff","#9f9","#f99","#f6f"],s=[],a=0,d="",c=[];this.setRegex=function(e){e=e.trim(),d=new RegExp("("+e+")","i")},this.getRegex=function(){return d.toString().replace(/^\/\\b\(|\)\\b\/i$/g,"").replace(/\|/g," ")},this.hiliteWords=function(t){if(null!=t&&t&&d&&!i.test(t.nodeName)){if(t.hasChildNodes())for(var n=0;n<t.childNodes.length;n++)this.hiliteWords(t.childNodes[n]);var l,p;if(3==t.nodeType)if((l=t.nodeValue)&&(p=d.exec(l))){for(var u=t;null!=u&&"SECTION"!=u.nodeName;)u=u.parentNode;var f=e.getIndices(u),h=c.length,y=!1;for(n=0;n<h;n++)c[n].h===f.h&&c[n].v===f.v&&(y=!0);y||c.push(f),s[p[0].toLowerCase()]||(s[p[0].toLowerCase()]=r[a++%r.length]);var g=document.createElement(o);g.appendChild(document.createTextNode(p[0])),g.style.backgroundColor=s[p[0].toLowerCase()],g.style.fontStyle="inherit",g.style.color="#000";var v=t.splitText(p.index);v.nodeValue=v.nodeValue.substring(p[0].length),t.parentNode.insertBefore(g,v)}}},this.remove=function(){for(var e,t=document.getElementsByTagName(o);t.length&&(e=t[0]);)e.parentNode.replaceChild(e.firstChild,e)},this.apply=function(e){if(null!=e&&e)return this.remove(),this.setRegex(e),this.hiliteWords(l),c}}return{id:"search",init:t=>{e=t,e.registerKeyboardShortcut("CTRL + Shift + F","Search"),document.addEventListener("keydown",(function(e){"F"==e.key&&(e.ctrlKey||e.metaKey)&&(e.preventDefault(),c())}),!1)},open:a,close:d,toggle:c}};export{e as default};

plugin/search/search.js

@@ -4,4 +4,4 @@
 	 * by navigatating to that slide and highlighting it.
 	 *
 	 * @author Jon Snyder <snyder.jon@gmail.com>, February 2013
-	 */return()=>{let e,t,n,i,o,l,r;function s(){t=document.createElement("div"),t.classList.add("searchbox"),t.style.position="absolute",t.style.top="10px",t.style.right="10px",t.style.zIndex=10,t.innerHTML='<input type="search" class="searchinput" placeholder="Search..." style="vertical-align: top;"/>\n\t\t</span>',n=t.querySelector(".searchinput"),n.style.width="240px",n.style.fontSize="14px",n.style.padding="4px 6px",n.style.color="#000",n.style.background="#fff",n.style.borderRadius="2px",n.style.border="0",n.style.outline="0",n.style.boxShadow="0 2px 18px rgba(0, 0, 0, 0.2)",n.style["-webkit-appearance"]="none",e.getRevealElement().appendChild(t),n.addEventListener("keyup",(function(t){if(13===t.keyCode)t.preventDefault(),function(){if(l){var t=n.value;""===t?(r&&r.remove(),i=null):(r=new c("slidecontent"),i=r.apply(t),o=0)}i&&(i.length&&i.length<=o&&(o=0),i.length>o&&(e.slide(i[o].h,i[o].v),o++))}(),l=!1;else l=!0}),!1),d()}function a(){t||s(),t.style.display="inline",n.focus(),n.select()}function d(){t||s(),t.style.display="none",r&&r.remove()}function c(t,n){var i=document.getElementById(t)||document.body,o=n||"EM",l=new RegExp("^(?:"+o+"|SCRIPT|FORM)$"),r=["#ff6","#a0ffff","#9f9","#f99","#f6f"],s=[],a=0,d="",c=[];this.setRegex=function(e){e=e.trim(),d=new RegExp("("+e+")","i")},this.getRegex=function(){return d.toString().replace(/^\/\\b\(|\)\\b\/i$/g,"").replace(/\|/g," ")},this.hiliteWords=function(t){if(null!=t&&t&&d&&!l.test(t.nodeName)){if(t.hasChildNodes())for(var n=0;n<t.childNodes.length;n++)this.hiliteWords(t.childNodes[n]);var i,f;if(3==t.nodeType)if((i=t.nodeValue)&&(f=d.exec(i))){for(var u=t;null!=u&&"SECTION"!=u.nodeName;)u=u.parentNode;var p=e.getIndices(u),h=c.length,y=!1;for(n=0;n<h;n++)c[n].h===p.h&&c[n].v===p.v&&(y=!0);y||c.push(p),s[f[0].toLowerCase()]||(s[f[0].toLowerCase()]=r[a++%r.length]);var g=document.createElement(o);g.appendChild(document.createTextNode(f[0])),g.style.backgroundColor=s[f[0].toLowerCase()],g.style.fontStyle="inherit",g.style.color="#000";var v=t.splitText(f.index);v.nodeValue=v.nodeValue.substring(f[0].length),t.parentNode.insertBefore(g,v)}}},this.remove=function(){for(var e,t=document.getElementsByTagName(o);t.length&&(e=t[0]);)e.parentNode.replaceChild(e.firstChild,e)},this.apply=function(e){if(null!=e&&e)return this.remove(),this.setRegex(e),this.hiliteWords(i),c}}return{id:"search",init:n=>{e=n,e.registerKeyboardShortcut("CTRL + Shift + F","Search"),document.addEventListener("keydown",(function(e){"F"==e.key&&(e.ctrlKey||e.metaKey)&&(e.preventDefault(),t||s(),"inline"!==t.style.display?a():d())}),!1)},open:a}}}));
+	 */return()=>{let e,t,n,o,i,l,s;function r(){t=document.createElement("div"),t.classList.add("searchbox"),t.style.position="absolute",t.style.top="10px",t.style.right="10px",t.style.zIndex=10,t.innerHTML='<input type="search" class="searchinput" placeholder="Search..." style="vertical-align: top;"/>\n\t\t</span>',n=t.querySelector(".searchinput"),n.style.width="240px",n.style.fontSize="14px",n.style.padding="4px 6px",n.style.color="#000",n.style.background="#fff",n.style.borderRadius="2px",n.style.border="0",n.style.outline="0",n.style.boxShadow="0 2px 18px rgba(0, 0, 0, 0.2)",n.style["-webkit-appearance"]="none",e.getRevealElement().appendChild(t),n.addEventListener("keyup",(function(t){if(13===t.keyCode)t.preventDefault(),function(){if(l){var t=n.value;""===t?(s&&s.remove(),o=null):(s=new f("slidecontent"),o=s.apply(t),i=0)}o&&(o.length&&o.length<=i&&(i=0),o.length>i&&(e.slide(o[i].h,o[i].v),i++))}(),l=!1;else l=!0}),!1),d()}function a(){t||r(),t.style.display="inline",n.focus(),n.select()}function d(){t||r(),t.style.display="none",s&&s.remove()}function c(){t||r(),"inline"!==t.style.display?a():d()}function f(t,n){var o=document.getElementById(t)||document.body,i=n||"EM",l=new RegExp("^(?:"+i+"|SCRIPT|FORM)$"),s=["#ff6","#a0ffff","#9f9","#f99","#f6f"],r=[],a=0,d="",c=[];this.setRegex=function(e){e=e.trim(),d=new RegExp("("+e+")","i")},this.getRegex=function(){return d.toString().replace(/^\/\\b\(|\)\\b\/i$/g,"").replace(/\|/g," ")},this.hiliteWords=function(t){if(null!=t&&t&&d&&!l.test(t.nodeName)){if(t.hasChildNodes())for(var n=0;n<t.childNodes.length;n++)this.hiliteWords(t.childNodes[n]);var o,f;if(3==t.nodeType)if((o=t.nodeValue)&&(f=d.exec(o))){for(var u=t;null!=u&&"SECTION"!=u.nodeName;)u=u.parentNode;var p=e.getIndices(u),h=c.length,y=!1;for(n=0;n<h;n++)c[n].h===p.h&&c[n].v===p.v&&(y=!0);y||c.push(p),r[f[0].toLowerCase()]||(r[f[0].toLowerCase()]=s[a++%s.length]);var g=document.createElement(i);g.appendChild(document.createTextNode(f[0])),g.style.backgroundColor=r[f[0].toLowerCase()],g.style.fontStyle="inherit",g.style.color="#000";var v=t.splitText(f.index);v.nodeValue=v.nodeValue.substring(f[0].length),t.parentNode.insertBefore(g,v)}}},this.remove=function(){for(var e,t=document.getElementsByTagName(i);t.length&&(e=t[0]);)e.parentNode.replaceChild(e.firstChild,e)},this.apply=function(e){if(null!=e&&e)return this.remove(),this.setRegex(e),this.hiliteWords(o),c}}return{id:"search",init:t=>{e=t,e.registerKeyboardShortcut("CTRL + Shift + F","Search"),document.addEventListener("keydown",(function(e){"F"==e.key&&(e.ctrlKey||e.metaKey)&&(e.preventDefault(),c())}),!1)},open:a,close:d,toggle:c}}}));

plugin/zoom/plugin.js

@@ -147,7 +147,7 @@ var zoom = (function(){
 	}
 
 	/**
-	 * Pan the document when the mosue cursor approaches the edges
+	 * Pan the document when the mouse cursor approaches the edges
 	 * of the window.
 	 */
 	function pan() {

test/test-auto-animate.html

@@ -110,21 +110,6 @@
 					Reveal.configure({ autoAnimate: true });
 				});
 
-				QUnit.test( 'Carries forward matching fragment visibility', assert => {
-					Reveal.slide(4);
-					assert.ok( !slides[5].h1.classList.contains( 'visible' ) )
-					Reveal.next();
-					Reveal.next();
-					Reveal.next();
-					assert.ok( slides[5].h1.classList.contains( 'visible' ) )
-					assert.ok( slides[5].h2.classList.contains( 'visible' ) )
-					assert.ok( !slides[5].h3.classList.contains( 'visible' ) )
-					Reveal.next();
-					assert.ok( slides[5].h3.classList.contains( 'visible' ) )
-					Reveal.next();
-					assert.ok( slides[6].slide === Reveal.getCurrentSlide() )
-				});
-
 				QUnit.test( 'Slide specific data-auto-animate-duration', assert => {
 					assert.timeout( 400 );
 					assert.expect( 1 );

test/test-destroy.html

@@ -0,0 +1,97 @@
+<!doctype html>
+<html lang="en">
+
+	<head>
+		<meta charset="utf-8">
+
+		<title>reveal.js - Test Dependencies</title>
+
+		<link rel="stylesheet" href="../dist/reveal.css">
+		<link rel="stylesheet" href="../node_modules/qunit/qunit/qunit.css">
+		<script src="../node_modules/qunit/qunit/qunit.js"></script>
+	</head>
+
+	<body style="overflow: auto;">
+
+		<div id="qunit"></div>
+		<div id="qunit-fixture"></div>
+
+		<div class="reveal deck1" style="display: none;">
+			<div class="slides">
+				<section>Slide content</section>
+			</div>
+		</div>
+
+		<div class="reveal deck2" style="display: none;">
+			<div class="slides">
+				<section>Slide content</section>
+			</div>
+		</div>
+
+		<script type="module">
+			import Reveal from '../dist/reveal.esm.js'
+			import Markdown from '../plugin/markdown/markdown.esm.js'
+
+			QUnit.module( 'Destroy' );
+
+			QUnit.test( 'Destruction during initialization', function( assert ) {
+
+				let deck = new Reveal( document.querySelector( '.deck1' ) );
+
+				deck.initialize({ plugins: [ Markdown ] });
+
+				let firstAttemptSuccess = false;
+				let repeatedAttemptSuccess = false;
+
+				try {
+					deck.destroy();
+					firstAttemptSuccess = true;
+				}
+				catch( error ) {
+					console.error( error );
+				}
+
+				assert.ok( firstAttemptSuccess, 'was successful' );
+
+				// should be able to destroy twice with no side effect
+				try {
+					deck.destroy();
+					repeatedAttemptSuccess = true;
+				}
+				catch( error ) {
+					console.error( error );
+				}
+
+				assert.ok( repeatedAttemptSuccess, 'destroyed twice with no exceptions' );
+
+			} );
+
+			QUnit.test( 'Destruction after initialization', function( assert ) {
+
+				assert.expect( 1 );
+				let done = assert.async( 1 );
+				let deck = new Reveal( document.querySelector( '.deck2' ) );
+
+				deck.initialize({ plugins: [ Markdown ] }).then(() => {
+					let wasSuccessful = false;
+
+					try {
+						deck.destroy();
+						wasSuccessful = true;
+					}
+					catch( error ) {
+						console.error( error );
+					}
+
+					if( wasSuccessful ) {
+						assert.ok( true, 'was successful' );
+					}
+
+					done();
+				});
+
+			} );
+		</script>
+
+	</body>
+</html>

test/test-iframes.html

@@ -36,68 +36,66 @@
 
 			QUnit.config.testTimeout = 30000;
 
-			Reveal.initialize({ viewDistance: 2 }).then( () => {
+			Reveal.initialize({ viewDistance: 2 });
 
-				var defaultIframe = document.querySelector( '.default-iframe' ),
-					preloadIframe = document.querySelector( '.preload-iframe' );
+			var defaultIframe = document.querySelector( '.default-iframe' ),
+				preloadIframe = document.querySelector( '.preload-iframe' );
 
-				QUnit.module( 'Iframe' );
+			QUnit.module( 'Iframe' );
 
-				QUnit.test( 'Using default settings', function( assert ) {
+			QUnit.test( 'Using default settings', function( assert ) {
 
-					Reveal.slide(1);
-					assert.strictEqual( defaultIframe.hasAttribute( 'src' ), false, 'not preloaded when within viewDistance' );
+				Reveal.slide(1);
+				assert.strictEqual( defaultIframe.hasAttribute( 'src' ), false, 'not preloaded when within viewDistance' );
 
-					Reveal.slide(2);
-					assert.strictEqual( defaultIframe.hasAttribute( 'src' ), true, 'loaded when slide becomes visible' );
+				Reveal.slide(2);
+				assert.strictEqual( defaultIframe.hasAttribute( 'src' ), true, 'loaded when slide becomes visible' );
 
-					Reveal.slide(1);
-					assert.strictEqual( defaultIframe.hasAttribute( 'src' ), false, 'unloaded when slide becomes invisible' );
+				Reveal.slide(1);
+				assert.strictEqual( defaultIframe.hasAttribute( 'src' ), false, 'unloaded when slide becomes invisible' );
 
-				});
+			});
 
-				QUnit.test( 'Using data-preload', function( assert ) {
+			QUnit.test( 'Using data-preload', function( assert ) {
 
-					Reveal.slide(1);
-					assert.strictEqual( preloadIframe.hasAttribute( 'src' ), true, 'preloaded within viewDistance' );
+				Reveal.slide(1);
+				assert.strictEqual( preloadIframe.hasAttribute( 'src' ), true, 'preloaded within viewDistance' );
 
-					Reveal.slide(2);
-					assert.strictEqual( preloadIframe.hasAttribute( 'src' ), true, 'loaded when slide becoems visible' );
+				Reveal.slide(2);
+				assert.strictEqual( preloadIframe.hasAttribute( 'src' ), true, 'loaded when slide becomes visible' );
 
-					Reveal.slide(0);
-					assert.strictEqual( preloadIframe.hasAttribute( 'src' ), false, 'unloads outside of viewDistance' );
+				Reveal.slide(0);
+				assert.strictEqual( preloadIframe.hasAttribute( 'src' ), false, 'unloads outside of viewDistance' );
 
-				});
+			});
 
-				QUnit.test( 'Using preloadIframes: true', function( assert ) {
+			QUnit.test( 'Using preloadIframes: true', function( assert ) {
 
-					Reveal.configure({ preloadIframes: true });
+				Reveal.configure({ preloadIframes: true });
 
-					Reveal.slide(1);
-					assert.strictEqual( defaultIframe.hasAttribute( 'src' ), true, 'preloaded within viewDistance' );
-					assert.strictEqual( preloadIframe.hasAttribute( 'src' ), true, 'preloaded within viewDistance' );
+				Reveal.slide(1);
+				assert.strictEqual( defaultIframe.hasAttribute( 'src' ), true, 'preloaded within viewDistance' );
+				assert.strictEqual( preloadIframe.hasAttribute( 'src' ), true, 'preloaded within viewDistance' );
 
-					Reveal.slide(2);
-					assert.strictEqual( defaultIframe.hasAttribute( 'src' ), true, 'loaded when slide becomes visible' );
-					assert.strictEqual( preloadIframe.hasAttribute( 'src' ), true, 'loaded when slide becomes visible' );
+				Reveal.slide(2);
+				assert.strictEqual( defaultIframe.hasAttribute( 'src' ), true, 'loaded when slide becomes visible' );
+				assert.strictEqual( preloadIframe.hasAttribute( 'src' ), true, 'loaded when slide becomes visible' );
 
-				});
+			});
 
-				QUnit.test( 'Using preloadIframes: false', function( assert ) {
+			QUnit.test( 'Using preloadIframes: false', function( assert ) {
 
-					Reveal.configure({ preloadIframes: false });
+				Reveal.configure({ preloadIframes: false });
 
-					Reveal.slide(0);
-					assert.strictEqual( defaultIframe.hasAttribute( 'src' ), false, 'not preloaded within viewDistance' );
-					assert.strictEqual( preloadIframe.hasAttribute( 'src' ), false, 'not preloaded within viewDistance' );
+				Reveal.slide(0);
+				assert.strictEqual( defaultIframe.hasAttribute( 'src' ), false, 'not preloaded within viewDistance' );
+				assert.strictEqual( preloadIframe.hasAttribute( 'src' ), false, 'not preloaded within viewDistance' );
 
-					Reveal.slide(2);
-					assert.strictEqual( defaultIframe.hasAttribute( 'src' ), true, 'loaded when slide becomes visible' );
-					assert.strictEqual( preloadIframe.hasAttribute( 'src' ), true, 'loaded when slide becomes visible' );
+				Reveal.slide(2);
+				assert.strictEqual( defaultIframe.hasAttribute( 'src' ), true, 'loaded when slide becomes visible' );
+				assert.strictEqual( preloadIframe.hasAttribute( 'src' ), true, 'loaded when slide becomes visible' );
 
-				});
-
-			} );
+			});
 		</script>
 
 	</body>