window.addEvent('domready',function(){
  var img = 0;
  function swapheader() {
    var frontBox = $('himg1');
    var rearBox = $('himg2');
    rearBox.setStyle('background-image','url('+fimages[img]+')');
    var fadeOut = new Fx.Tween(frontBox,{duration: 'long'}).start('opacity',1,0).chain(function() {
      frontBox.setStyle('background-image','url('+fimages[img]+')');
      if ( img == fimages.length-1 ) {
        img = 0;
      } else {
        img++;
      }
      var fadeIn = new Fx.Tween(frontBox).start('opacity',0,1).chain(function(){
        setTimeout(swapheader,4000);
      })
    });
  }
  swapheader();
});