var p=0;
  var speed=20;   // vary this to suit, larger value - slower speed

  window.onload=function() 
  { plogos(); }

  function plogos() 
  {
	 document.getElementById('container').style.backgroundPosition=p+'px 0';
	 p--;    //change this to p-- for right to left direction

     setTimeout('plogos()',speed);
  }