Index: wp-admin/admin-header.php
===================================================================
--- wp-admin/admin-header.php	(revision 22944)
+++ wp-admin/admin-header.php	(working copy)
@@ -97,7 +97,7 @@
 
 ?>
 </head>
-<body class="wp-admin no-js <?php echo apply_filters( 'admin_body_class', '' ) . " $admin_body_class"; ?>">
+<body class="wp-admin wp-core-ui no-js <?php echo apply_filters( 'admin_body_class', '' ) . " $admin_body_class"; ?>">
 <script type="text/javascript">
 	document.body.className = document.body.className.replace('no-js','js');
 </script>
Index: wp-includes/class-wp-editor.php
===================================================================
--- wp-includes/class-wp-editor.php	(revision 22944)
+++ wp-includes/class-wp-editor.php	(working copy)
@@ -113,7 +113,7 @@
 			$buttons .= '<a id="' . $editor_id . '-tmce" class="wp-switch-editor switch-tmce" onclick="switchEditors.switchto(this);">' . __('Visual') . "</a>\n";
 		}
 
-		echo '<div id="wp-' . $editor_id . '-wrap" class="wp-editor-wrap ' . $switch_class . '">';
+		echo '<div id="wp-' . $editor_id . '-wrap" class="wp-core-ui wp-editor-wrap ' . $switch_class . '">';
 
 		if ( self::$editor_buttons_css ) {
 			wp_print_styles('editor-buttons');
Index: wp-includes/css/buttons.css
===================================================================
--- wp-includes/css/buttons.css	(revision 22944)
+++ wp-includes/css/buttons.css	(working copy)
@@ -34,9 +34,9 @@
   1.0 - Button Layouts
 ---------------------------------------------------------------------------- */
 
-.button,
-.button-primary,
-.button-secondary {
+.wp-core-ui .button,
+.wp-core-ui .button-primary,
+.wp-core-ui .button-secondary {
 	display: inline-block;
 	text-decoration: none;
 	font-size: 12px;
@@ -57,43 +57,43 @@
 }
 
 /* Remove the dotted border on :focus and the extra padding in Firefox */
-button::-moz-focus-inner,
-input[type="reset"]::-moz-focus-inner,
-input[type="button"]::-moz-focus-inner,
-input[type="submit"]::-moz-focus-inner {
+.wp-core-ui button::-moz-focus-inner,
+.wp-core-ui input[type="reset"]::-moz-focus-inner,
+.wp-core-ui input[type="button"]::-moz-focus-inner,
+.wp-core-ui input[type="submit"]::-moz-focus-inner {
 	border-width: 1px 0;
 	border-style: solid none;
 	border-color: transparent;
 	padding: 0;
 }
 
-.button.button-large,
-.button-group.button-large .button {
+.wp-core-ui .button.button-large,
+.wp-core-ui .button-group.button-large .button {
 	height: 30px;
     line-height: 28px;
     padding: 0 12px 2px;
 }
 
-.button.button-small,
-.button-group.button-small .button {
+.wp-core-ui .button.button-small,
+.wp-core-ui .button-group.button-small .button {
 	height: 21px;
 	line-height: 20px;
 	padding: 0 8px 1px;
 }
 
-.button.button-hero,
-.button-group.button-hero .button {
+.wp-core-ui .button.button-hero,
+.wp-core-ui .button-group.button-hero .button {
 	font-size: 14px;
 	height: 46px;
 	line-height: 44px;
 	padding: 0 36px;
 }
 
-.button:active {
+.wp-core-ui .button:active {
 	outline: none;
 }
 
-.button.hidden {
+.wp-core-ui .button.hidden {
 	display: none;
 }
 
@@ -101,8 +101,8 @@
   2.0 - Default Button Style
 ---------------------------------------------------------------------------- */
 
-.button,
-.button-secondary {
+.wp-core-ui .button,
+.wp-core-ui .button-secondary {
 	background: #f3f3f3;
 	background-image: -webkit-gradient(linear, left top, left bottom, from(#fefefe), to(#f4f4f4));
 	background-image: -webkit-linear-gradient(top, #fefefe, #f4f4f4);
@@ -114,12 +114,12 @@
 	text-shadow: 0 1px 0 #fff;
 }
 
-.button.hover,
-.button:hover,
-.button-secondary:hover,
-.button.focus,
-.button:focus,
-.button-secondary:focus {
+.wp-core-ui .button.hover,
+.wp-core-ui .button:hover,
+.wp-core-ui .button-secondary:hover,
+.wp-core-ui .button.focus,
+.wp-core-ui .button:focus,
+.wp-core-ui .button-secondary:focus {
 	background: #f3f3f3;
 	background-image: -webkit-gradient(linear, left top, left bottom, from(#fff), to(#f3f3f3));
 	background-image: -webkit-linear-gradient(top, #fff, #f3f3f3);
@@ -131,18 +131,18 @@
 	color: #222;
 }
 
-.button.focus,
-.button:focus,
-.button-secondary:focus {
+.wp-core-ui .button.focus,
+.wp-core-ui .button:focus,
+.wp-core-ui .button-secondary:focus {
 	-webkit-box-shadow: 1px 1px 1px rgba(0,0,0,.2);
 	box-shadow: 1px 1px 1px rgba(0,0,0,.2);
 }
 
-.button.active,
-.button.active:hover,
-.button.active:focus,
-.button:active,
-.button-secondary:active {
+.wp-core-ui .button.active,
+.wp-core-ui .button.active:hover,
+.wp-core-ui .button.active:focus,
+.wp-core-ui .button:active,
+.wp-core-ui .button-secondary:active {
 	background: #eee;
 	background-image: -webkit-gradient(linear, left top, left bottom, from(#f4f4f4), to(#fefefe));
 	background-image: -webkit-linear-gradient(top, #f4f4f4, #fefefe);
@@ -157,11 +157,11 @@
  	box-shadow: inset 0 2px 5px -3px rgba( 0, 0, 0, 0.5 );
 }
 
-.button[disabled],
-.button:disabled,
-.button-secondary[disabled],
-.button-secondary:disabled,
-.button-disabled {
+.wp-core-ui .button[disabled],
+.wp-core-ui .button:disabled,
+.wp-core-ui .button-secondary[disabled],
+.wp-core-ui .button-secondary:disabled,
+.wp-core-ui .button-disabled {
 	color: #aaa !important;
 	border-color: #ddd !important;
 	background-image: -webkit-gradient(linear, left top, left bottom, from(#f9f9f9), to(#f4f4f4)) !important;
@@ -180,7 +180,7 @@
   3.0 - Primary Button Style
 ---------------------------------------------------------------------------- */
 
-.button-primary {
+.wp-core-ui .button-primary {
 	background-color: #21759b;
 	background-image: -webkit-gradient(linear, left top, left bottom, from(#2a95c5), to(#21759b));
 	background-image: -webkit-linear-gradient(top, #2a95c5, #21759b);
@@ -197,10 +197,10 @@
 	text-shadow: 0 1px 0 rgba(0,0,0,0.1);
 }
 
-.button-primary.hover,
-.button-primary:hover,
-.button-primary.focus,
-.button-primary:focus {
+.wp-core-ui .button-primary.hover,
+.wp-core-ui .button-primary:hover,
+.wp-core-ui .button-primary.focus,
+.wp-core-ui .button-primary:focus {
 	background-color: #278ab7;
 	background-image: -webkit-gradient(linear, left top, left bottom, from(#2e9fd2), to(#21759b));
 	background-image: -webkit-linear-gradient(top, #2e9fd2, #21759b);
@@ -215,17 +215,17 @@
 	text-shadow: 0 -1px 0 rgba(0,0,0,0.3);
 }
 
-.button-primary.focus,
-.button-primary:focus {
+.wp-core-ui .button-primary.focus,
+.wp-core-ui .button-primary:focus {
 	border-color: #0e3950;
 	-webkit-box-shadow: inset 0 1px 0 rgba(120,200,230,0.6), 1px 1px 2px rgba(0,0,0,0.4);
 	box-shadow: inset 0 1px 0 rgba(120,200,230,0.6), 1px 1px 2px rgba(0,0,0,0.4);
 }
 
-.button-primary.active,
-.button-primary.active:hover,
-.button-primary.active:focus,
-.button-primary:active {
+.wp-core-ui .button-primary.active,
+.wp-core-ui .button-primary.active:hover,
+.wp-core-ui .button-primary.active:focus,
+.wp-core-ui .button-primary:active {
 	background: #1b607f;
 	background-image: -webkit-gradient(linear, left top, left bottom, from(#21759b), to(#278ab7));
 	background-image: -webkit-linear-gradient(top, #21759b, #278ab7);
@@ -240,9 +240,9 @@
 	text-shadow: 0 1px 0 rgba(0,0,0,0.1);
 }
 
-.button-primary[disabled],
-.button-primary:disabled,
-.button-primary-disabled {
+.wp-core-ui .button-primary[disabled],
+.wp-core-ui .button-primary:disabled,
+.wp-core-ui .button-primary-disabled {
 	color: #94cde7 !important;
 	background: #298cba !important;
 	border-color: #1b607f !important;
@@ -256,7 +256,7 @@
   4.0 - Button Groups
 ---------------------------------------------------------------------------- */
 
-.button-group {
+.wp-core-ui .button-group {
 	position: relative;
 	display: inline-block;
 	white-space: nowrap;
@@ -264,25 +264,25 @@
 	vertical-align: middle;
 }
 
-.button-group > .button {
+.wp-core-ui .button-group > .button {
 	display: inline-block;
 	border-radius: 0;
 	margin-right: -1px;
 	z-index: 10;
 }
 
-.button-group > .button-primary {
+.wp-core-ui .button-group > .button-primary {
 	z-index: 100;
 }
 
-.button-group > .button:hover {
+.wp-core-ui .button-group > .button:hover {
 	z-index: 20;
 }
 
-.button-group > .button:first-child {
+.wp-core-ui .button-group > .button:first-child {
 	border-radius: 3px 0 0 3px;
 }
 
-.button-group > .button:last-child {
+.wp-core-ui .button-group > .button:last-child {
 	border-radius: 0 3px 3px 0;
 }
Index: wp-includes/js/media-views.js
===================================================================
--- wp-includes/js/media-views.js	(revision 22944)
+++ wp-includes/js/media-views.js	(working copy)
@@ -1099,6 +1099,9 @@
 				uploader: true
 			});
 
+			// Ensure core UI is enabled.
+			this.$el.addClass('wp-core-ui');
+
 			// Initialize modal container view.
 			if ( this.options.modal ) {
 				this.modal = new media.view.Modal({
Index: wp-includes/media.php
===================================================================
--- wp-includes/media.php	(revision 22944)
+++ wp-includes/media.php	(working copy)
@@ -1505,7 +1505,7 @@
 	</script>
 
 	<script type="text/html" id="tmpl-media-modal">
-		<div class="media-modal">
+		<div class="media-modal wp-core-ui">
 			<h3 class="media-modal-title">{{ data.title }}</h3>
 			<a class="media-modal-close media-modal-icon" href="#" title="<?php esc_attr_e('Close'); ?>"></a>
 		</div>
