For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:lashkevi/openSUSE_Tumbleweed/home:lashkevi.repo
zypper refresh
zypper install crystalsvg-icon-theme
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:lashkevi/15.6/home:lashkevi.repo
zypper refresh
zypper install crystalsvg-icon-theme
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:lashkevi/15.5/home:lashkevi.repo
zypper refresh
zypper install crystalsvg-icon-theme
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:lashkevi/15.4/home:lashkevi.repo
zypper refresh
zypper install crystalsvg-icon-theme
For 15.3 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:lashkevi/15.3/home:lashkevi.repo
zypper refresh
zypper install crystalsvg-icon-theme