Merge branch 'master' into pr/12670

less/button-groups.less

@@ -220,7 +220,17 @@
 
 
 // Checkbox and radio options
+//
+// In order to support the browser's form validation feedback, powered by the
+// `required` attribute, we have to "hide" the inputs via `opacity`. We cannot
+// use `display: none;` or `visibility: hidden;` as that also hides the popover.
+// This way, we ensure a DOM element is visible to position the popover from.
+//
+// See https://github.com/twbs/bootstrap/pull/12794 for more.
+
 [data-toggle="buttons"] > .btn > input[type="radio"],
 [data-toggle="buttons"] > .btn > input[type="checkbox"] {
-  display: none;
+  position: absolute;
+  z-index: -1;
+  opacity: 0;
 }

less/list-group.less

@@ -62,6 +62,7 @@ a.list-group-item {
   &:hover,
   &:focus {
     text-decoration: none;
+    color: @list-group-link-hover-color;
     background-color: @list-group-hover-bg;
   }
 }

less/mixins.less

@@ -602,7 +602,7 @@
   &.active,
   .open .dropdown-toggle& {
     color: @color;
-    background-color: darken(@background, 8%);
+    background-color: darken(@background, 10%);
         border-color: darken(@border, 12%);
   }
   &:active,

less/variables.less

@@ -662,6 +662,7 @@
 @list-group-disabled-text-color: @list-group-disabled-color;
 
 @list-group-link-color:         #555;
+@list-group-link-hover-color:   @list-group-link-color;
 @list-group-link-heading-color: #333;