Your ROOT_URL in app.ini is https://source.parasitstudio.de:63000/ but you are visiting https://source.parasitstudio.de/wirtz/OpenAudio_ArduinoLibrary/src/commit/cce309ffd299c512d32092810b3fd6828844f286/docs/bootstrap/css
You should set ROOT_URL correctly, otherwise the web may not work correctly.
Chip Audette