update en-US

lib/locales/en-US/translation.json

@@ -293,6 +293,7 @@
         "list_page_display": "You can speed up list page display by invalidating.",
         "tab_switch": "Save tab-switching in the browser",
         "save_edit": "Save edit tab and history tab switching in the browser and make it object for forward/back command of the browser.",
-        "by_invalidating": "By invalidating, you can make page transition as the only object for forward/back command of the browser."
- }
+        "by_invalidating": "By invalidating, you can make page transition as the only object for forward/back command of the browser.",        
+        "Custom CSS": "Custom CSS"
+      }
 }