see https://seirdy.one/posts/2020/11/23/website-best-practices/#about-fonts and https://infinnie.github.io/blog/2017/systemui.html I like this explanation: https://github.com/w3c/csswg-drafts/issues/3658#issuecomment-1277943116 After reading many discussions, I'm still not sure about it. I'll keep it for now.