Navbar in main content? Why?

Okay, so if the navbar is in the #main div, this precludes the possibility of making a layout with an expandable navbar and header and fixed center width area that includes the sidebars and content that has margin:auto to stay centered, since the markup to keep the columns in place requires margin attributes...

I think this is not ideal, since i'ts nice to have a full width header and then to have fixed width content, especially if you're making a site that will have articles on it, and it's nice for large screens to read those articles in the center of the screen.

just a thought.

hope this makes sense.