I use 20px font size in Hacker News - Zenburn Dark (by incrediblygood [1]) to make usable, the default fontsize and the bright colorscheme is fatiguing to my eyes.
[1] https://userstyles.org/styles/97106/hacker-news-zenburn-dark
[1] https://userstyles.org/styles/97106/hacker-news-zenburn-dark
Reading on mobile devices, or worse, high-DPI e-ink, is a nightmare.
There's supposed to be a custom-per-user CSS hack in the works, but that's been the response for years.