menuHover = function() {
	var menuElements = document.getElementById("head_menu").getElementsByTagName("li");
	for (var i=0; i<menuElements.length; i++) {
		menuElements[i].onmouseover=function() {
			this.className+=" hover";
		}
		menuElements[i].onmouseout=function() {
			this.className=this.className.replace(new RegExp(" hover\\b"), "");
		}
	}
}
if (window.attachEvent) window.attachEvent("onload", menuHover);