function nav_overs(elem){
	var pnav = document.getElementById(elem);
			
	var nav_items = pnav.getElementsByTagName('li');
	for(i=0;i<nav_items.length;i++){
				
		if(nav_items[i].className != 'act'){
			nav_items[i].onmouseover=function(){this.className = 'act';}
			nav_items[i].onmouseout=function(){this.className = '';}
		}							
	}
}

window.onload=function(){
	nav_overs('nav');
}