Cross site duplicate (as answer to the dark theme thread).
I was quite surprised to see a meta.3dprinting.SE question in my HNQ feed and even more so when it turned out to be a Japanese question! The icon seems to be borked, however with HNQs "instability" I don't know if there is a way to check if that's a caching issue or something else.
What did work however was changing this:
background-position: 0 0;
Browser: Firefox 76.0.1 64-Bit OS: Windows 10 Pro