Merge pull request #671 from yolouiese/636-responsive-breakpoint-switcher-viewport-icons

#636: Responsive breakpoint switcher - fixed viewport icons styling

Author: omiroshnichenko

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

@@ -59,6 +59,13 @@
         opacity: 1;
     }
 
+    &:not([disabled]) {
+        &:hover {
+            background-color: #4a4542;
+            opacity: 1;
+        }
+    }
+
     img {
         height: 20px;
         width: 30px;