Blog Page Content Wider Than Static Page Content?

This is driving me nuts. I have modified a child theme of twenty twelve to give nice rounded corners, shadows, and borders. On static pages everything lines up nicely. On the blog page however, the content seems wider and pushes everything outwards making the layout look incorrect.

I have searched for a couple hours now and tried several different stylesheet adjustments. I can affect the blog page, but only at a cost of affecting the static pages too.

So, my question … is there a way to separate the blog post page from the static page CSS so I can adjust the margins and padding of the blog post page(s) without affecting the static pages?

You can see the difference below …

http://69.172.198.95/~bbgroup/
http://69.172.198.95/~bbgroup/blog/