sfHover = function() {

var sfEls = document.getElementById("nav").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);