fe.settings:getUserBoardSettings - non array given[operate] - Endchan Magrathea
 >>/11844/
Try:

background-image: url("/.media/869459fc7013c39b00fa82882e6dc1f8-imagejpeg.jpg");

That should solve frontend/mirror problem.

We're working on a project that might be allow us to do such modifications. But for now, the solution above have to suffice.