All:

Thanks for help.

The html structure is like:

```
<div id="container" style="position:relative; top:100px; left:100px; width:200px; height:300px; overflow: auto;">
    <div id="absoluteinner" style="position:absolute; top:10px; left:10px; width:100px; height:100px; background-color:red;">
    </div>
    <div id="staticinner" style="width:100px; height:800px; background-color:purple;">
    </div>
</div>

```

I thought that absoluteinner can keep a fixed position relative to its container, but when I scroll the container, the absoluteinner moves as the staticinner. How can I make it position fixed?