(function(){
  if ($('accordion')){
    var panels = $$('#accordion .panel');
    panels.each(function(panel, i){
      panel.observe('mouseenter', function(){
        panels.invoke('removeClassName', 'active').invoke('addClassName', 'inactive');
        panel.removeClassName('inactive').addClassName('active');
        panels.invoke('removeClassName', 'displaced');
        panels.slice(panels.indexOf(panel) + 1).invoke('addClassName', 'displaced');
      });
    });
  }
})();