Ticket #33360: 33360.patch

src/wp-admin/css/customize-nav-menus.css

@@ -609 +609 @@
         border-left: none;
         border-right: none;
         background: #fff;
+        -webkit-transition: all 0.15s;
+        transition: all 0.15s;
 }
 
 #available-menu-items .open .accordion-section-title,
@@ -700 +702 @@
 #available-menu-items .accordion-section-content {
         padding: 1px 15px 15px 15px;
         margin: 0;
-        min-height: 120px;
         max-height: 290px;
 }