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);