sfHover=function() {
    var sfEls=document.getElementById('nav').getElementsByTagName('li');
    for(var i=0; i<sfEls.length; i++) {
        sfEls[i].onmouseover=function() {
            this.className+=' sfhover';
            document.getElementById('framed').style.visibility='hidden';
        }
        sfEls[i].onmouseout=function() {
            this.className=this.className.replace(new RegExp(' sfhover\\b'),'');
            document.getElementById('framed').style.visibility='visible';
        }
    }
}