Arrange three columns with a fixed combined width. The center column will have dynamic content, while the left and right columns should fill out the remaining space equally.
For example, see this demonstration: http://jsfiddle.net/htKje/
<div class="container">
<div class="bg"></div>
<div>Lorem Ipsum</div>
<div class="bg"></div>
</div>
CSS :
.container { width:500px; }
.bg {background:#CCC; }