Ticket #31542: 31542.patch

wp-admin/css/themes.css

@@ -916 +916 @@
 @media only screen and (max-width: 780px) {
         body.folded .theme-overlay .theme-wrap,
         .theme-overlay .theme-wrap {
-                top: 0; /* The adminmenu isn't fixed on mobile, so this can use the full viewport height */
+                top: 46px; /* Top value should equal to #wpadminbar height */
                 right: 0;
                 bottom: 0;
                 left: 0;