These are the Vimix GTK and icon themes for snap apps. Vimix is a flat Material Design theme for GTK 3, GTK 2 and Gnome-Shell which supports GTK 3 and GTK 2 based desktop environments like Gnome, Unity, Budgie, Pantheon, XFCE, Mate, etc. This snap provides the GTK themes in a form that can be used by other snapped applications.
This snap is packaged from vinceliuice's repositories. You can download the full themes from there: