How to horizontally auto-stretch columns either side of a fixed central column?

Hi,

The situation: I have a three-column website. The two side columns are for a horizontally-repeating background image, and the central one is for actual content. The central column is a fixed size, and needs to stay in the horizontal center of the screen.

The background image of the central column needs to seamlessly join to the background image of the side columns. To make this possible I have the left column's "background-position" set to "right", and the right column's set to "left".

Now what I need is to make the side columns auto-stretch to fill the screen. Anyone know how I can do this?

Thanks

 

I should mention that I'm using div tags for the columns.

 

get screen width and adjust side columns accordingly.

 

@ you-me Is that something I can automate so it works on all different screen sizes? How do I do that?
Thanks