function initMenu() {
 if (document.all&&document.getElementById) {
  var navRoot=document.getElementById('top-menu'); 
  var nodes=navRoot.getElementsByTagName('li');
  for (i=0;i<nodes.length;i++) {
   var node=nodes[i];    
   node.onmouseover=function() {
    this.className+=(this.className!="")?' hover':'hover';
   }    
   node.onmouseout=function() {
    this.className=(this.className=="hover")?'':this.className.replace(' hover', ''); 
   }
  }
 }
}

window.onload=initMenu