Narrow width for categories/post list?

Hi

How do I change the posts list / categories list to follow the pages/posts in narrow width?

Currently all my post pages are wide as they follow the “General > Layout” width which is wider for the front page, while I have the other pages and posts on narrow width. I’d like the post lists to follow the style of those narrow pages.

Thanks for any help, Justin

The page I need help with: [log in to see the link]