sfHover = function() {
   var sfEls = document.getElementById("nav").getElementsByTagName("li");
   for (var i=0; i<sfEls.length; ++i) {
      sfEls.onmouseover=function() {
         clearTimeout(this.timer);
         if(this.className.indexOf("sfhover") == -1)
            this.className+="sfhover";
      }
      sfEls.onmouseout=function() {
         this.timer = setTimeout(sfHoverOut.bind(this), 20);
      }
   }
}

function sfHoverOut() {
   clearTimeout(this.timer);
   this.className=this.className.replace(new RegExp("sfhover\\b"), "");
}

if (window.attachEvent) window.attachEvent("onload", sfHover);