Index: src/wp-admin/css/common.css
===================================================================
--- src/wp-admin/css/common.css	(revision 29293)
+++ src/wp-admin/css/common.css	(working copy)
@@ -2507,15 +2507,25 @@
 	line-height: 48px;
 	width: 48px;
 	height: 48px;
+	transition: .1s color ease-in-out,
+	            .1s background ease-in-out;
 }
 
+body.plugin-install-php .tb-close-icon:focus,
 body.plugin-install-php .tb-close-icon:hover,
+body.import-php .tb-close-icon:focus,
 body.import-php .tb-close-icon:hover,
+body.plugins-php .tb-close-icon:focus,
 body.plugins-php .tb-close-icon:hover,
+body.update-core-php .tb-close-icon:focus,
 body.update-core-php .tb-close-icon:hover,
+body.index-php .tb-close-icon:focus,
 body.index-php .tb-close-icon:hover {
 	background: #0074a2;
 	color: #fff;
+	outline: none;
+	-webkit-box-shadow: none;
+	box-shadow: none;
 }
 
 body.plugin-install-php .tb-close-icon:before,
Index: src/wp-admin/css/customize-controls.css
===================================================================
--- src/wp-admin/css/customize-controls.css	(revision 29293)
+++ src/wp-admin/css/customize-controls.css	(working copy)
@@ -176,8 +176,8 @@
 	border-right: 1px solid #ddd;
 	color: #444;
 	cursor: pointer;
-	-webkit-transition: color ease-in .1s;
-	transition: color ease-in .1s;
+	transition: .1s color ease-in-out,
+	            .1s background ease-in-out;
 }
 
 .control-panel-back {
@@ -192,8 +192,10 @@
 	background: #eee;
 	border-right: 1px solid #ddd;
 	cursor: pointer;
-	-webkit-transition: left ease-in-out .18s, color ease-in .1s;
-	transition: left ease-in-out .18s, color ease-in .1s;
+	transition: .18s left ease-in-out,
+	            .1s color ease-in-out,
+	            .1s background ease-in-out;
+
 }
 
 .collapsed .control-panel-back {
Index: src/wp-admin/css/themes.css
===================================================================
--- src/wp-admin/css/themes.css	(revision 29293)
+++ src/wp-admin/css/themes.css	(working copy)
@@ -431,6 +431,8 @@
 	border: 0;
 	border-left: 1px solid #ddd;
 	background-color: transparent;
+	transition: .1s color ease-in-out,
+	            .1s background ease-in-out;
 }
 
 .theme-overlay .theme-header .close:hover:before,
@@ -458,6 +460,8 @@
 	text-align: center;
 	border: 0;
 	border-right: 1px solid #ddd;
+	transition: .1s color ease-in-out,
+	            .1s background ease-in-out;
 }
 
 .theme-overlay .theme-header .close:hover,
@@ -468,6 +472,9 @@
 .theme-overlay .theme-header .left:focus {
 	background: #0074a2;
 	color: #fff;
+	outline: none;
+	-webkit-box-shadow: none;
+	box-shadow: none;
 }
 
 .theme-overlay .theme-header .left.disabled,
@@ -1387,8 +1394,8 @@
 	color: #444;
 	cursor: pointer;
 	text-decoration: none;
-	-webkit-transition: color ease-in .1s;
-	transition: color ease-in .1s;
+	transition: .1s color ease-in-out,
+	            .1s background ease-in-out;
 }
 
 .theme-install-overlay .close-full-overlay:hover,
Index: src/wp-includes/css/media-views.css
===================================================================
--- src/wp-includes/css/media-views.css	(revision 29293)
+++ src/wp-includes/css/media-views.css	(working copy)
@@ -147,6 +147,8 @@
 	height: 48px;
 	z-index: 1000;
 	color: #777;
+	transition: .1s color ease-in-out,
+	            .1s background ease-in-out;
 }
 
 .media-modal-close span.media-modal-icon {
@@ -2677,6 +2679,8 @@
 	text-align: center;
 	border: 0;
 	border-left: 1px solid #ddd;
+	transition: .1s color ease-in-out,
+	            .1s background ease-in-out;
 }
 
 .edit-attachment-frame .edit-media-header .left {
@@ -2728,6 +2732,9 @@
 .edit-attachment-frame .edit-media-header .left:focus {
 	background: #0074a2;
 	color: #fff;
+	outline: none;
+	-webkit-box-shadow: none;
+	box-shadow: none;
 }
 
 .edit-attachment-frame .media-frame-content,