Conflicts:
- `app/helpers/theme_helper.rb`:
Conflict because of different theming system.
Adapted upstream's changes.
- `vite.config.mts`:
Conflict because of different theming system.
Adapted upstream's changes.
Conflicts:
- `vite.config.mts`:
Upstream moved its theming system to a plug-in, where we had our own.
Adapted the file as well as our own plugin to adopt the same mechanisms.