It has been a great experience going through the wealth of MDN learning materials, I will like to suggest that there should be provisions for dark mode especially for the learning part; This is because, just like myself many developers work at night and having this feature will help to prevent any negative effect that can be caused by long time steering on white screen.
Reaching the decision makers could be achieved through the quoted GitHub discussion in the quoted post (quote-ception ): https://github.com/mdn/yari/discussions/2539.
It just seems that this isn’t a priority at the moment.