sfHover = function() {
   var sfEls = document.getElementById("header").getElementsByTagName("li");
  for (var i=0; i<sfEls.length; i++) {
         sfEls[i].onmouseover=function() {
             this.className+=" sfhover";
         }
         sfEls[i].onmouseout=function() {
             this.className=this.className.replace(new RegExp(" sfhover\\b"), "");
         }
     }
 }
if (window.attachEvent) window.attachEvent("onload", sfHover);