Merge branch 'v4-dev' of https://github.com/twbs/bootstrap into v4-dev

scss/_alert.scss

@@ -5,7 +5,7 @@
 .alert {
   padding: $alert-padding;
   margin-bottom: $spacer-y;
-  border: 1px solid transparent;
+  border: $alert-border-width solid transparent;
   @include border-radius($alert-border-radius);
 
   // Improve alignment and spacing of inner content

scss/_card.scss

@@ -169,10 +169,10 @@
 
 // Card image caps
 .card-img-top {
-  @include border-radius(.25rem .25rem 0 0);
+  @include border-radius($card-border-radius-inner $card-border-radius-inner 0 0);
 }
 .card-img-bottom {
-  @include border-radius(0 0 .25rem .25rem);
+  @include border-radius(0 0 $card-border-radius-inner $card-border-radius-inner);
 }
 
 
@@ -257,7 +257,7 @@
         }
         &:last-child {
           @include border-left-radius(0);
-          
+
           .card-img-top {
             border-top-left-radius: 0;
           }

scss/_dropdown.scss

@@ -10,8 +10,8 @@
     display: inline-block;
     width: 0;
     height: 0;
-    margin-left: .25rem;
     margin-right: .25rem;
+    margin-left: .25rem;
     vertical-align: middle;
     content: "";
     border-top: $caret-width solid;
@@ -45,8 +45,8 @@
   min-width: 160px;
   padding: 5px 0;
   margin: 2px 0 0; // override default ul
-  color: $body-color;
   font-size: $font-size-base;
+  color: $body-color;
   text-align: left; // Ensures proper alignment if parent has it changed (e.g., modal footer)
   list-style: none;
   background-color: $dropdown-bg;
@@ -172,7 +172,7 @@
 
 // Allow for dropdowns to go bottom up (aka, dropup-menu)
 //
-// Just add .dropup after the standard .dropdown class and you're set, bro.
+// Just add .dropup after the standard .dropdown class and you're set.
 // TODO: abstract this so that the navbar fixed styles are not placed here?
 
 .dropup,

scss/_images.scss

@@ -40,12 +40,11 @@
 .figure {
   // Ensures the caption's text aligns with the image.
   display: inline-block;
+}
 
-  > img {
-    @extend .img-fluid;
-    margin-bottom: ($spacer-y / 2);
-    line-height: 1;
-  }
+.figure-img {
+  margin-bottom: ($spacer-y / 2);
+  line-height: 1;
 }
 
 .figure-caption {

scss/_nav.scss

@@ -92,7 +92,7 @@
 
 .nav-pills {
   @include clearfix();
-  
+
   .nav-item {
     float: left;
 

scss/_reboot.scss

@@ -196,6 +196,16 @@ img {
 }
 
 
+// iOS "clickable elements" fix for role="button"
+//
+// Fixes "clickability" issue (and more generally, the firing of events such as focus as well)
+// for traditionally non-focusable elements with role="button"
+// see https://developer.mozilla.org/en-US/docs/Web/Events/click#Safari_Mobile
+
+[role="button"] {
+  cursor: pointer;
+}
+
 //
 // Tables
 //

scss/_variables.scss

@@ -526,6 +526,7 @@ $modal-sm:                    300px !default;
 $alert-padding:               15px !default;
 $alert-border-radius:         $border-radius !default;
 $alert-link-font-weight:      bold !default;
+$alert-border-width:          $border-width !default;
 
 $alert-success-bg:            $state-success-bg !default;
 $alert-success-text:          $state-success-text !default;

scss/mixins/_forms.scss

@@ -5,7 +5,7 @@
 
 @mixin form-control-validation($color) {
   // Color the label and help text
-  .help-block,
+  .text-help,
   .form-control-label,
   .radio,
   .checkbox,