Wondering if there is a night shade
Your Operating System might offer a simple solution for this. Check under Control Panel → Accessibility, or something similar (you didn’t tell us what your OS is).
Hello,
there a 2 ways to customize your colors:
-
Tools -> Options -> Personalization -> Category: Firefox Themes -> Option: Preinstalles Themes
If you choose the darkest theme there, you may also want to adapt the Icon sytle (``Tools → Options → View → Category: User Interface → Option: Icon style`) -
Tools -> Options -> Application Colors -> Category: Custom Colors
. Most likely you may be interested in Document background on General