Hello,
As i also wanted a customized login screen for my keycloak installation this week, i cloned the default keycloak theme to a new custom theme(mytheme).
The procedure for the cloning was:
I took the org.keycloak.keycloak-themes-22.0.1.jar file and unzip it to a new folder(e.g default-theme).
From the above(default-theme) folder, i copied the keycloak subfolder to
keycloak/themes/mytheme folder.
Also from default-theme/base/login folder i copied the files login.ftl & template.ftl to keycloak/themes/mytheme/login folder
2) I modified the login.ftl & template.ftl according to my needs.
3) From the keycloak gui i changed my realm το use my custom theme.
akops