window.addEvent("domready",function() {
  //settings
  var duration = 80000;
  var length = 1280;
  var count = 0;
  
  var tweener;
  
  // Executes the standard tween on the background position
  var run = function() {
    tweener.tween("background-position","-" + (++count * length) + "px 0px");
  };
  
  // Defines the tween
  tweener = $("clouds").setStyle("background-position","0px 0px").set("tween",{ 
    duration: duration, 
    transition: Fx.Transitions.linear,
    onComplete: run,
    link: "cancel"
  });
  
  // Starts the initial run of the transition
  run();  
});