Using it on Firefox for Windows it didn't work well, for me it only worked on the bet365 site, the only other one that changed was youtube, but it was in a light pink tone with white fonts, in the end I couldn't see anything.
Thanks for the feedback! I will manage to test it on Firefox for Windows as soon as possible (I primarily work with a mac).
Edit: I tested the add-on on Firefox for Windows and it works well. I don't know how to reproduce the problem you're facing. Could you please file an issue on GitHub: https://github.com/easonwong-de/Adaptive-Tab-Bar-Colour/issues ?
