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