diff --git src/wp-admin/js/customize-widgets.js src/wp-admin/js/customize-widgets.js
index df4c8d777b..ba9e3d1b43 100644
--- src/wp-admin/js/customize-widgets.js
+++ src/wp-admin/js/customize-widgets.js
@@ -602,7 +602,7 @@
 			$customizeSidebar = $( '.wp-full-overlay-sidebar-content:first' );
 			this.container.addClass( 'wide-widget-control' );
 
-			this.container.find( '.widget-content:first' ).css( {
+			this.container.find( '.form:first' ).css( {
 				'max-width': this.params.width,
 				'min-height': this.params.height
 			} );