http://www.borderstogo.com/clearance.html is a Flexible Width Site. The page expands to fill the user's screen resolution, whatever that might be.

I'm using a series of DIVs to give the impression of a series of columns with 2, 3, 4 or even 5 columns across, whatever will fit in the user's display. It looks pretty good on some screen resolutions, but on ones just a bit too small for a full additional column to the right, I end up with a lot of white space on the right because I am using a fixed margin between each <div class="mainbox">. If you open the link above and adjust the window width a bit, you will see just what I am talking about.

If I set the left and right margin to auto, a single div will float in the middle of the page.

I think this is just beyond the reach of CSS and I would need to turn to JavaScript and browser sniffing to detect screen resolution. But I thought I would ask if anyone here can come up with a trick to handle it.