//Behaviors
Event.addBehavior({
  '.hide_help_box:click' : function(e) {
    Effect.Fade(this.parentNode.parentNode, { duration: 0.25 });
    document.cookie = this.rel + '=1;path=/;expires=Tue, 2 Jun 2015 00:00:00 UTC;';
    Event.stop(e);
  }
});