Examples updates (#24898)

* fix cover nav

* Improve signin visuals and alignment with that flexbox love

* rewrite cover example in flexbox

* lighten signin bg

* first pass at pricing example

* redo examples index with data file

* tighten up spacing a bit

* update navbar descriptions

* link pricing

* move that back

* property order

* Fix test errors.

* Compress pricing.png.

* add form validation example

* remove that

* rename that

* restyle and space out

* fix errors

* change order

* cleanup album css and styles

* tweak examples index

* make it a badge

* options

* improve sticky footer alignment

* redesign example index

* brand new blog layout

* start new screenshots

* new product example page a la apple

* add email field

* fix linter, remove unused blog css

* hook up feather icons to start

* redo dashboard

* fix linting

* add floating labels example

* formatting

* formatting

* lint

* fix values on select

* optional input, plus input group

* new dashboard image

* start to reboot the offcanvas example

* updated images

* new offcanvas mostly implemented

* linting

* edit description

* more description changes

* - Add vertical margin to album hero buttons for when they're stacked
- Adjust font-size and padding for pricing header and hero
- Fix checkout's stacked column margins, plus update their check/radio
markup
- Update product's utilities to be responsive
- Made blog cards somewhat responsive (needs a bit more work tbh)

* drop leading zero

* more linting

* swap empty images for holder, fix border

* dist the docs

* navbars have no margin-bottom to begin

* add css var, tweak padding for mobile

* comment headers

* nix commented out code

* nix the navbar structure for a custom one, stack it on mobile

* tweak heading button group for mobile

* Removed narrow jumbotron and justified nav examples as these are easily accomplished with new components in v4

* improve card sizing on pricing

* update and compress

docs/4.0/examples/blog/blog.css

@@ -1,89 +1,83 @@
-/*
- * Globals
- */
-@media (min-width: 48em) {
-  html {
-    font-size: 18px;
+/* stylelint-disable selector-list-comma-newline-after */
+
+.blog-header {
+  line-height: 1;
+  border-bottom: 1px solid #e5e5e5;
+}
+
+.blog-header-logo {
+  font-family: "Playfair Display", Georgia, "Times New Roman", serif;
+  font-size: 2.25rem;
+}
+
+.blog-header-logo:hover {
+  text-decoration: none;
+}
+
+h1, h2, h3, h4, h5, h6 {
+  font-family: "Playfair Display", Georgia, "Times New Roman", serif;
+}
+
+.display-4 {
+  font-size: 2.5rem;
+}
+@media (min-width: 768px) {
+  .display-4 {
+    font-size: 3rem;
   }
 }
 
-body {
-  font-family: Georgia, "Times New Roman", Times, serif;
-  color: #555;
-}
-
-h1,
-.h1,
-h2,
-.h2,
-h3,
-.h3,
-h4,
-.h4,
-h5,
-.h5,
-h6,
-.h6 {
-  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
-  font-weight: 400;
-  color: #333;
-}
-
-/*
- * Override Bootstrap's default container.
- */
-.container {
-  max-width: 60rem;
-}
-
-/*
- * Masthead for nav
- */
-.blog-masthead {
-  margin-bottom: 3rem;
-  background-color: #428bca;
-  box-shadow: inset 0 -.1rem .25rem rgba(0, 0, 0, .1);
-}
-
-/* Nav links */
-.nav-link {
+.nav-scroller {
   position: relative;
-  padding: 1rem;
-  font-weight: 500;
-  color: #cdddeb;
-}
-.nav-link:hover,
-.nav-link:focus {
-  color: #fff;
-  background-color: transparent;
+  z-index: 2;
+  height: 2.75rem;
+  overflow-y: hidden;
 }
 
-/* Active state gets a caret at the bottom */
-.nav-link.active {
-  color: #fff;
+.nav-scroller .nav {
+  display: -webkit-box;
+  display: -ms-flexbox;
+  display: flex;
+  -ms-flex-wrap: nowrap;
+  flex-wrap: nowrap;
+  padding-bottom: 1rem;
+  margin-top: -1px;
+  overflow-x: auto;
+  text-align: center;
+  white-space: nowrap;
+  -webkit-overflow-scrolling: touch;
 }
-.nav-link.active::after {
-  position: absolute;
-  bottom: 0;
-  left: 50%;
-  width: 0;
-  height: 0;
-  margin-left: -.3rem;
-  vertical-align: middle;
-  content: "";
-  border-right: .3rem solid transparent;
-  border-bottom: .3rem solid;
-  border-left: .3rem solid transparent;
+
+.nav-scroller .nav-link {
+  padding-top: .75rem;
+  padding-bottom: .75rem;
+  font-size: .875rem;
 }
 
+.card-img-right {
+  height: 100%;
+  border-radius: 0 3px 3px 0;
+}
+
+.flex-auto {
+  -ms-flex: 0 0 auto;
+  -webkit-box-flex: 0;
+  flex: 0 0 auto;
+}
+
+.h-250 { height: 250px; }
+@media (min-width: 768px) {
+  .h-md-250 { height: 250px; }
+}
+
+.border-top { border-top: 1px solid #e5e5e5; }
+.border-bottom { border-bottom: 1px solid #e5e5e5; }
+
+.box-shadow { box-shadow: 0 .25rem .75rem rgba(0, 0, 0, .05); }
+
 /*
  * Blog name and description
  */
-.blog-header {
-  padding-bottom: 1.25rem;
-  margin-bottom: 2rem;
-  border-bottom: .05rem solid #eee;
-}
 .blog-title {
   margin-bottom: 0;
   font-size: 2rem;
@@ -100,25 +94,6 @@ h6,
   }
 }
 
-/*
- * Main column and sidebar layout
- */
-
-/* Sidebar modules for boxing content */
-.sidebar-module {
-  padding: 1rem;
-}
-.sidebar-module-inset {
-  padding: 1rem;
-  background-color: #f5f5f5;
-  border-radius: .25rem;
-}
-.sidebar-module-inset p:last-child,
-.sidebar-module-inset ul:last-child,
-.sidebar-module-inset ol:last-child {
-  margin-bottom: 0;
-}
-
 /* Pagination */
 .blog-pagination {
   margin-bottom: 4rem;