It's been tough to test some of the things that should work, because you can't always override a style specification with no specification...
Anyway, you can style #footer {} with either width: 80%; margin: 5em auto 0; or padding: 0 5em; to make a narrower space to hold the seals.
There is at least one other method you could use, so let me know if one of those works when you do it in the actual stylesheet.