Styling is done with `ctx.set_style`, but creating a nice style isn't very easy at the moment (basically you'll have to tweak constants in code, and then recompile). I'm working on making it easier as we speak though!
I don't have a plan for that right now. I'm not even sure a web page can know what the RGB pattern of the display is so it can do proper sub-pixel anti-aliasing.
I'm sort of hoping high-dpi screens will make this a moot point very soon :)
egui author here! Fell free to shoot me any questions. You can try egui in your browser at https://www.egui.rs/
My company Rerun.io is entirely built on egui so that we get the same high-performance UI on the web as on native. Give it a spin at https://app.rerun.io/