var ButtonFlick = {
  start: function () {
    $$('#top-nav li a').each(function(el){
      if (el.hasClass('active')) return;
      var text = el.getText();
      var button = new Element('div', {'class':'btn'})
       .setText(text)
       .injectInside(el);
      var buttonfx = new Fx.Slide(button, {
        'wait':false,
        'transition':Fx.Transitions.Cubic.easeInOut,
        'duration':350
      });
      buttonfx.wrapper.setStyles({
        'position': 'absolute',
        'top': 0,
        'left': 0
      });
      el.addEvents({
        'mouseenter': function () {
          buttonfx.slideOut();
        },
        'mouseleave': function () {
          buttonfx.slideIn();
        }
      });
    });
  }
}

window.addEvent('load', function(){
  ButtonFlick.start();
});