Lack of adjustments.

Więcej problemu z tym dodatkiem niż pożytku.
Owszem działa, ale w kratkę, raz strona jest ciemna, innym razem wstrętnie jasna.

Owl causes issues with the Youtube site. It occasionally does not work if YT is opened in tabs.. but the most disturbing issue is when you open the picture in fullscreen: Owl inverts all colors.
BTW there are dark theme addons for YT exclusively, but I could not get them to function with Owl installed. Even if you add a "disable owl on site xyz" exception, it would occasionally invert already inverted site (which then appears messed up) and it would completely fail to function if YT is opened in a tab.
That is quite annoying! Currently not usable for me!!

Everything is fine, but for an issue with Facebook. Whenever it is on, the horizontal scroll bar runs to the left, gets very small, some times it even disappears, and the content inside the window becomes unstable when trying to use the H scroll bar.

Generally a good extension, but unfortunately not available for Firefox Beta on Android.