Does mobify work with background images loaded through css?
By default mobify excludes the desktop markup from the page so any background images defined there won’t work on your mobile site. You would need to set the background images in the css for your mobify project in order to work.
I think I misread your question. I imagine you were asking about our responsive image solution, and not Mobify Studio (our adaptive templating tool). Sorry about that.
Unfortunately automating responsive background images with Mobify.js isn’t possible at the moment. It’s on our roadmap though, so please feel free to check back periodically.