@benjifrank The location of css assets have changed. It is now in CUSTOM/public/assets/css (starting from 1.21.0 it seems). The templates are also not into custom directly , but into templates/base it seems. Not 100% sure but it seems like that unlikes color themes, there can only be 1 template (?) because the template names don't have a theme prefix....
Anyway, so, my directory structure is like this:
root@fd219d58-a046-4087-910f-ffca7d16dfee:/app/data/custom# find .
.
./templates
./templates/base
./public
./public/assets
./public/assets/img
./public/assets/css
./public/assets/css/theme-arc-red.css
I put this in my app.ini:
[ui]
THEMES = gitea-auto,gitea-light,gitea-dark,arc-red
DEFAULT_THEME = arc-red
Restarted the app.
And then I do red color scrollbars etc.