I came looking for a simple hack and i found gold... Thanks!!!

incorrect statusbar color in pwa mode on firefox android with this addon

Благослови господь, мои глаза спасены!

Extremely flexible; if a site doesn't play well with a certain format, there's like three more to fall back on. On top of that you can extensively change how the "dark" theme is displayed! Features support for blacklists and even time scheduling. This is the best dark-theme extension I've ever used.

Basically a requirement for OLED devices. Very easy to turn on/off per site basis