<html>
<body>
Document canvas should be big enough to fit both blue and red (relative positioned) rectangles (ie. have scrollbars if they don't fit to the view)
<div style="width: 500px; height: 500px; position: absolute; border: 2px solid blue;">
<div style="width: 500px; height: 500px; left: 300px; top:300px; position: relative; border: 2px solid red;">
</div>
</div>