Appears on web as a mobile site, sort of

I have a website that looks like a mobile site (sort of). It has a menu, then the post, followed by a comment box.
It should have a header, with a post underneath and a left column navigation menu.
I restored a copy to WP 3.8.3, then I updated to 3.9.1. Same thing. I have turned off every plugin, I have turned them all on. I checked my permalinks with the default setting and with my preferred setting of blog name/postname (with no category).

Has anyone come across something like this before? Any ideas?

Anyway, thank you for taking your time to consider my problem. It is appreciated.