sfHover = function() {
var sfEls = document.getElementById("topnav").getElementsByTagName("LI");
sfElsLength = sfEls.length;
for (var i=0; i<sfElsLength; 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);