Css frames centering

[rmi]

I'm using css to create frame-like environment for my site.

Frames are pretty much like this example here

Whole width in my page is 900px.

Problem: Whole package is situated in left and I need it to be in center. How can I move all 'frames' centered on all size of screens?

-rmi-

[chechu]

Please put a link to the site where you wish to use this script.