Had we learned and implemented style sheets well, especially the Cascade and the original use of the !important declaration the answer would be user style sheet. I fully Sarah's assessment for today's real #a11y priorities. Not preference really. Dark mode compromises my vision.

I don't know that I agree. I've been trying to explain to folks that CSS in JS screws with user styles, making users have to modify or switch their workarounds. The response has pretty much been "meh, development needs are more important". I'm not sure it was about us.