fixed separator color

Former-commit-id: d8178a1c09458e8cdab8547076e9e95a5d092534

extension/ui/editor/editor.css

@@ -115,4 +115,8 @@ img[type=button].remove-highlight-disabled:hover {
     img[type=button].remove-highlight-disabled {
         background-color: #4a4a4a;
     }
+
+    .separator {
+        background-color: #b3b3b3;
+    }
 }