Source (link to git-repo or to original if based on someone elses unmodified work): https://github.com/GNOME/gtk/tree/master/gtk/theme/Adwaita
If you, like me, hate how the Adwaita scrollbars look under some apps like firefox or libreoffice, this is for you.
It basically imports all of the adwaita theme, but replaces the scrollbars with minimal ones.
I decided to make this since Firefox moved to quantum and the stylish scripts i used to tweak scrollbars stopped working.
To install, hust extract the archive content in ~/.local/share/themes, so that you have: ~/.local/share/themes/AdwaitaMS/
Then you have two choices.
1) Use AdwaitaMS system wide
2) Use AdwaitaMS with Firefox (or whatever), via:
# GTK_THEME=AdwaitaMS firefox
(I use the latter)