I hate to offer some unsolicited critique of something I happily use for free... but I have to say this somewhere to just get it out. That's what this place is for, right?

The new MDN visual design fucking sucks.

It's like a purposeful example I might make for my students - of "what not to do." There were a few things they could have done to improve MDN for sure. Instead, they didn't improve it. They just "changed it." That is always a bad move. Now everything just has less contrast and is floating around with nothing to anchor it. Didn't they show it to anyone and get feedback along the way? "So, we made all the fonts closer to the same size, removed any differentiation in weight so that everything will look the same and just kinda blur out and put people to sleep, and just in general dulled everything out as much as possible - and also here's this logo thing too."