Well, the Author has not noticed that in tabbar, tabs have WHITE crosses. And when on Win10 x64 I hover a mouse over an active tab, it all becomes white. No cross visible. :) On Win 8.1 x64 however, it works very well, as it should.
Could you please submit an issue with a more verbose description to the Github Issues page? I'm not sure what the problem is, and I would like to have major bugs fixed in version 2. https://github.com/spikespaz/firefox-nativedark/issues
