function prepareNav() {
	var nav = document.getElementById('nav');
	var buttons = nav.getElementsByTagName('li');
	  for(i=0; i < buttons.length; i++) {
			buttons[i].onmouseover = function() { this.$oldclasses = this.className; this.className = this.className+' hover'; }
			buttons[i].onmouseout  = function() { this.className = this.$oldclasses; }
		}
}

window.onload = prepareNav;