materia-gtk-theme from home:kamarada:15.3:dev project
Select Your Operating System
Add repository and install manually
For openSUSE Leap 15.3 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:kamarada:15.3:dev/openSUSE_Leap_15.3/home:kamarada:15.3:dev.repo zypper refresh zypper install materia-gtk-theme