<html>
<head>
<style>
#outer {
position: absolute;
top: 0px;
left: 0px;
height: 300px;
width: 300px;
overflow: auto;
background-color: green;
}
#inner {
background-color: blue;
}
#overlap {
width: 500px;
height: 500px;
background-color: yellow;
}
</style>
</head>
<body>
<div id="outer">
<div id="inner"></div>
</div>
<div id="overlap"></div>
</body>
</html>