A simple CSS Menu with slider

Found this nice piece of code while browsing . few lines of code to create a nice menu slider.

Example

Part 1 - HTML

<div id="menu">
 <div id="m-top">
  <ul>
   <li><a href="#">Home</a></li>
   <li><a href="#">About Us</a></li>
   <li><a href="#">F.A.Q.</a></li>
   <li><a href="#">Contact</a></li>
  </ul>
 </div>
 <div id="m-slider">
  <div id="slider"></div>
 </div>
</div> 

Part 2 - Javascript

Now we add Javascript event that listen for mousemove on div that holds menu.

window.onload=function(){

 var offsetLeft=$('menu').offsetLeft;

 Event.observe('menu', 'mousemove', function(event){

  coordinateX=Event.pointerX(event)-offsetLeft;
  $('slider').style.marginLeft=coordinateX-20+'px';

 });

}