Your ROOT_URL in app.ini is https://source.parasitstudio.de:63000/ but you are visiting https://source.parasitstudio.de/wirtz/Teensy-reSID/src/commit/7c3fbea00875b3f2bbdb8225c5867c5a199d0aec/examples/reSID
You should set ROOT_URL correctly, otherwise the web may not work correctly.
Frank Bösing