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); }