style(sidebar): sligthly adjust loading icon to match the favicon

extension/sidebar.css

@@ -153,7 +153,7 @@ body,
 
 /*Huge thanks to @tobiasahlin at http://tobiasahlin.com/spinkit/ */
 .three-dot-bounce {
-  margin: 0px 6px 0px 5px;
+  margin: 0px 6px 0px 6px;
   width: 15px;
   text-align: center;
 }