function init_menu() {
  var items = $$('.navEl');
  items.each(function(item) {
    Event.observe(item,'mouseover',function() {
      Element.addClassName(this,'Hover');
    }.bind(item));
    Event.observe(item,'mouseout',function() {
      Element.removeClassName(this,'Hover');
    }.bind(item));
  });
}

Event.observe(window,'load',init_menu);