#636: Responsive breakpoint switcher

 - fix static test

Author: omiroshnichenko

app/code/Magento/PageBuilder/view/adminhtml/web/css/source/_buttons.less

@@ -61,7 +61,7 @@
 
     &:not([disabled]) {
         &:hover {
-            background-color: #4A4542;
+            background-color: #4a4542;
             opacity: 1;
         }
     }