How to increase width of single.php page

Hi all,

I have a site which basically has a a 3 column layout – sidebar, main content, sidebar, all neatly centred on the “home.php” page, and then when you click through to posts it converts to a 2 column layout – content, sidebar.

My theme doesn’t support 3 columns on the posts page by default, but I’ve hacked it a bit and I can add a left-hand side sidebar to single.php which ends up looking pretty good.

The problem is, the site has a set width of 960px, so I need to change the width in style.css, which is fine – but then on home.php, everything is no longer aligned in the center, but sitting over to the left.

I was thinking I could create a custom css document for it, but despite my efforts, I can’t seem to work out how to make single.php use it… 🙁 Any ideas?

Thanks a lot for any help you can offer!