sfHover = function() {
    if (document.getElementById("main_nav_menu")) {
	    var sfEls = document.getElementById("main_nav_menu").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);