Ticket #28681: 28681.diff

src/wp-includes/js/tinymce/skins/wordpress/wp-content.css

@@ -45 +45 @@
 }
 
 .aligncenter,
-dl.aligncenter {
+dl.aligncenter,
+.html5-captions .wp-caption.aligncenter {
         display: block;
         margin-left: auto;
         margin-right: auto;