html>img /* autoscroll override for Firefox */

{

  width: 0!important;

  height: 28px!important;

  padding-left: 28px!important;

  background: url(/images/icons/autoscroll2.png);

}

http://www.sitepoint.com/

Sitepoint have this useless but cool feature if you hold down the middle click to autoscroll the page - they have replaced the image that indicates scrolling

Replacing autoscroll image in Firefox

css, image

CSS