function menutko() 
{
    if (document.all&&document.getElementById)
    {
        navigace = document.getElementById("menu");
        for (i=0; i<navigace.childNodes.length; i++) 
        {
            node = navigace.childNodes[i];
            if (node.nodeName=="LI"){
                node.onmouseover=function(){
                    this.className+=" over";
                }
                node.onmouseout=function(){
                    this.className=this.className.replace("over", "");
                }
            }
        }
	}
}

window.onload = menutko;