<html>
<body>
<div style="height:100px;background-color:yellow">
<div style="float:left;height:500px;background-color:green">Hello world</div>
</div>
<div style="overflow:hidden; height:100px; border:2px solid black">Does the float intrude?
<span style="float:right;width:100px;background-color:purple;height:400px"></span>
</div>
<div>This text should not overlap the purple float?  Will this happen? I'm really not sure.
This is a test of some of the strange behavior you will find when using overflow auto or scroll, etc.
</div>