If you download the "visual-regression-results " artifact from Checks, you see this broke a lot of stuff.

Ah well I see...
Sadly it's quite cumbersome to debug this without being able to build the project locally. At least my PR could be considered as a POC for the neccessary bugfix. Maybe someone else can pick this up where I left off.
Let me restate that it is not possible to just style everything with body > div > * while fixing the related issue. As far as I can tell the darkmode styling needs to be crafted more carefully on a per-element basis.

Edit: Alternatively it might be possible (at least as a temporary solution) to only apply my fix to the documentation pages since I don't see any visual regression results for these pages so I think this should be fine.