Help With A Variable Background

I need a little help figuring out how to set up a div with a background that adjusts based on the length of the content.

Here’s a visual for what I’m working with…

This is a WordPress Blog and I need for the background image to adjust so that the white highlight is always at the end of the post/page title. I had it working in FF by using a div with a background of a plain blue line, then covering that with a span containing the title. But that didn’t line up correctly in IE7 and just plain didn’t work in IE6.

I’m not looking for a finished solution….just hoping for a little guidance in a way to attack the problem.