Sometimes on a web page you have a div container with 2 or more divs within. In many cases, you'll want the background from one of the divs to fill the container div. Unfortunately, the div style property height does not support a percentage value as of XHTML 1.1. Instead, you can "fool" the div by repeating the background on the container control like this:
<div id="container" style="background-image: url('containerbkg.gif'); background-repeat: repeat-y;">
<div id="menu" style="float: left; width: 100px;">
Item 1<br/>
Item 2
</div>
<div id="body" style="margin-left: 100px; width: 300pt;">
Body goes here<br/><br/>
Body continues here<br/><br/>
Body ends here.
</div>
</div>