var ool = window.onload;
window.onload = function() {
   if (ool != null) ool();
   nav();
   
 }
 
 function nav() {
  if($('nav')){
    ($$('#nav > li')).each(function(elm) {
      elm.onmouseover = function () { this.className = this.className + " hover"; }  
      elm.onmouseout = function () { this.className = this.className.replace(" hover", ""); }  
   });
  }
 }