Oooo! A bonafide trick from Thomas Steiner. Chrome will soon be supporting SVG favicons (e.g. ). And you can embed CSS within an SVG with a

Safari also supports SVG, but it's different...

You specify the color, so there is no opportunity there for a dark mode situation. A little surprising, since Apple is so all-in on this dark mode stuff. I have no idea if they plan to address that or what.