sfDrop = function() {
  var sfEls = document.getElementById("nav").getElementsByTagName("li");
  var droppedMenu = document.getElementById("last");
  droppedMenu.className+=" sfhover";
  for (var i=0; i<sfEls.length; i++) {
    sfEls[i].onmouseover=function() {
      droppedMenu.className=droppedMenu.className.replace(new RegExp(" sfhover\\b"), "");
      if (document.all) this.className+=" sfhover";
    }
    sfEls[i].onmouseout=function() {
      if (document.all) this.className=this.className.replace(new RegExp(" sfhover\\b"), "");
    }
  }
}

if (document.getElementById) {
  window.onload=sfDrop;
}