I decided to look at the different backgrounds. At first it was working fine, but after a few different ones it wasn't always working (it would just stay on the current background), then after a while it stopped working altogether. I could still switch to no background but then was stuck on it. However, upon refreshing it worked fine. I know it doesn't help that I can't reproduce it but here you go.
I have Debian Linux 8.6, and my browser is Chromium version 53.0.2785.143.
