I've been able to add CSS to set max width for the banner and overlay, but it doesn't center the image or work with small screens, AND then I still have to deal with the menu/brand ares (see screencaps).
I'm thinking that setting a maximum width for the site that applies to
banner (and overlay)
menu
page content
galleries
etc.
But I can't seem to track down appropriate CSS.
(Note: I'm a designer, not a developer or programmer, so this is part of my ongoing learning experience.)