​x
 
<html>
<head>
<script type="text/javascript" src="/jquery/jquery.js"></script>
<script type="text/javascript">
$(document).ready(function(){
  $(".btn1").click(function(){
    $("body").animate({backgroundPosition:"40% 40%"},0);
  });
  $(".btn2").click(function(){
    $("body").animate({backgroundPosition:"0% 0%"},0);
  });
});
</script>
</head>
<body style="background-image:url(/i/eg_background.jpg);background-repeat:no-repeat;background-attachment:fixed;">
<p>This is a paragraph.</p>
<button class="btn1">Animate</button>
<button class="btn2">Reset</button>
</body>
</html>
​