The mobile theme for PhysicsOverflow has been released. It's a slight fork of Noah Y's q2a-mobile-theme, which was released 4-years ago.
As you can see, it's still a work-in-progress, but it was necessary to do so, due to certain developments in the search engine world. Meanwhile, you can get the old version of the theme back on most popular mobile browsers. Usually, the option would be available in the browser's app menu, e.g.
Apologies for the inconvenience caused, the mobile theme will be updated soon to be more usable (not just to google's search bot, but to real human beings).