Had it utterly broken and replaced
All teh css went haywire, couldn't see tabs, extensions, no menu buttons.
Replaced it with https://github.com/rafaelmardojai/firefox-gnome-theme
For those who will find this issue here:
- this theme has a softlink pointing to
/usr/share/themes/Firefox-Gnome-Maia/chrome/
placed here~/.mozilla/firefox/[your profile]/chrome/
- rename or remove that entire
/chrome/
dir - run an installer of the abovementioned theme, please mind the web bash
curl -s -o- https://raw.githubusercontent.com/rafaelmardojai/firefox-gnome-theme/master/scripts/install-by-curl.sh | bash