Completely ripped from https://github.com/UCCNetsoc/keycloak. Why reinvent the wheel when someone has already made a brilliant version of it? Made a few changes like changing the logo and some of the buttons.
As for how it's installed, we're running Keycloak inside a docker container. So we just have this theme mapped to a folder inside /opt/jboss/keycloak/themes.