Event.observe(window, "load", init_an_hmenu);

function init_an_hmenu(e)
{
  var i = 0;
  var as = $$("li.rollbtn a");
  
  for(i=0;i<as.length;i++)
  {
    Event.observe(as[i], "mouseover", an_hmenu_roll);
    Event.observe(as[i], "mouseout", an_hmenu_restore);
  }
}

function an_hmenu_roll(e)
{
  var li = Event.findElement(e, "li.rollbtn");
  if(li)
  {
    Element.writeAttribute(li, "style", "background-position:bottom center");
  }
}

function an_hmenu_restore(e)
{
  var li = Event.findElement(e, "li.rollbtn");
  if(li)
  {
    Element.writeAttribute(li, "style", "background-position:top center");
  }
}