<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<style type="text/css">
.a{height:10000px; }
img{position:fixed;left:0px;top:0px}
</style>
<img src="images/logo.png" />
<div class="a"><div>
<style type="text/css">
.a{height:10000px; }
img{position:fixed;left:0px;top:0px}
</style>
<img src="images/logo.png" />
<div class="a"><div>
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript" src="jquery-1.6.1.min.js"></script>
<style type="text/css">
.cudiv{
overflow:auto;
height:100px;
width:200px;
border:1px solid #000;
}
.div2{
height:1000px;
}
</style>
<script type="text/javascript">
$(function(){ $('.cudiv').scroll(function(){
var top = $(this).scrollTop();
if(top == 0){
//设置.
}
});
});
</script>
</head>
<body>
<input id="txt" />
<div class="cudiv">
<div class="div2">
</div> </div>
</body>
</html>