subHover =function() {
   var subEls = document.getElementById("nav").getElementsByTagName("LI");
   for (var i=0; i<subEls.length; i++) {
            subEls[i].onmouseover=function() {
                   this.className+=" subhover";
            }
            subEls[i].onmouseout=function() {
                   this.className=this.className.replace(new RegExp(" subhover\\b"), "");
            }
       }
   }
if (window.attachEvent) window.attachEvent("onload", subHover);