function menuFix() {
    var sfEls = document.getElementById("nav_main").getElementsByTagName("li");
    
    for (var i = 0; i < sfEls.length; i++) {
        sfEls[i].onmouseover = function() {
            this.className += (this.className.length > 0 ? " " : "") + "sfhover";
        }
        sfEls[i].onMouseDown = function() {
            this.className += (this.className.length > 0 ? " " : "") + "sfhover";
        }
        sfEls[i].onMouseUp = function() {
            this.className += (this.className.length>0? " ": "") + "sfhover";
        }
        sfEls[i].onmouseout = function() {
            this.className = this.className.replace(new RegExp("( ?|^)sfhover\\b"), "");
        }
    }
}

menuFix();