Basilisk • Re: Need help with French and other requests

But that's no longer the case.

Excuse me? It is. There is no need to muck around in about:config. The setting mentioned is directly exposed in the preferences UI. It will also not force light or dark mode on all websites (that is what extensions like Swarth are for...) but rather, it sends a signal to websites which implement this kind of choice by browser signals to switch to the preferred colour scheme that is provided by the website.