function menu() {
  if (document.all && document.getElementById) {
      mm = document.getElementById("mainnav");
      for (i=0; i<mm.childNodes.length; i++) {
          node = mm.childNodes[i];
       //   if (node.nodeName=="LI") {
              node.onmouseover=function() {
                  this.className+=" over";
                  //alert(this.className);
              }
              node.onmouseout=function(){
                  this.className=this.className.replace(" over", "")
              }
     //     }
      }
  }
}