Added a rollover animation

It really isn't an animation - the border-radius gets smaller by 1 pixel. It's more like a confirmation that the browser is reading your mouse movements.

src/MediaWiki:Gadget-afchelper.css

@@ -14,6 +14,11 @@ input.button {
   -moz-border-radius: 3px; /* Firefox compatibility */
 }
 
+input.button:hover {
+  border-radius: 2px;
+  -moz-border-radius: 2px; /* Firefox compatibility */
+}
+
 #afcHelper_accept_button {
   background-color: #adfcad;
 }