Index: src/wp-admin/js/press-this.js
===================================================================
--- src/wp-admin/js/press-this.js	(revision 31548)
+++ src/wp-admin/js/press-this.js	(working copy)
@@ -604,7 +604,7 @@
 		 */
 		function renderNotice( msg, error ) {
 			var $alerts = $( '.editor-wrapper div.alerts' ),
-				className = error ? 'is-error' : 'is-notice';
+				className = error ? 'alert is-error' : 'alert is-notice';
 
 			$alerts.append( $( '<p class="' + className + '">' ).text( msg ) );
 		}