arc-gruvbox-theme : A flat theme with transparent elements ( https://github.com/cyrinux/arc-gruvbox-theme )
gruvbox-material-gtk-theme : Gruvbox Material theme for GTK ( https://github.com/sainnhe/gruvbox-material-gtk )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a thegreatmcpain
For Paludis use this rsync : rsync://gentoo.zugaina.org/thegreatmcpain-portage
If you have a problem : ycarus(-at-)zugaina.org