Ah! That was it. Almost there…
When I removed the min-width, the logo became responsive, but was once again getting cut off on desktops, even with the “background-size: contain !important;” command.
I played around with firebug, and realized that the title-area still had a smaller width, so I changed that to 501px, and now it works at all sizes! (At least from what I can tell with the “responsive design” tool. I haven’t tested on real devices yet.)
I wish I hadn’t waited so long to get help. I think of everything I have learned so far, it is the header/title/widget-right area that seems the most complex.
Thank you so much, Eric!
Elizabeth