Gitea: Custom themes not working

So I got the container Gitea running and it works, mounted this way:

volumes:
  - /home/user/docker-data/gitea:/data

According to gitea docs:

Add a CSS file to $GITEA_PUBLIC/public/css/theme-<theme-name>.css. The value of $GITEA_PUBLIC of your instance can be queried by calling gitea help and looking up the value of “CustomPath”.

Add <theme-name> to the comma-separated list of setting THEMES in app.ini

Calling the cli and gitea help gives me: CustomPath: /data/gitea (GITEA_CUSTOM)

So if /home/user/docker-data/gitea:/data then /data/gitea/home/user/docker-data/gitea/gitea which follows that

$GITEA_PUBLIC/public/css//home/user/docker-data/gitea/gitea/public/css.

Which I have, and where I put the files in: https://i.imgur.com/GSdYNAr.png . app.ini has

[ui]
DEFAULT_THEME                     = gitea
THEMES                            = gitea,arc-green,gitea-modern,plex

and I have it to choose from in gitea: https://i.imgur.com/a9BoWI4.png

Only problem is: They do nothing.

On a side note: The path has changed in Gitea 1.15, there the file needs to be placed in $GITEA_CUSTOM/public/assets/css I have public/css and public/assets/css. Both not working.