[mdaniel]

whew, seeing that makes me have bottomless sympathy for ladybird since I (quite literally) cannot imagine the amount of energy it would take to implement CSS in a modern browser

put another way: I'd get great thrills if any proposal to whatwg had to come bundled with the assembly(perl? bash? pick some language) implementation of any such proposal so the authors share the intellectual load of "but, wait, how would we _implement this_?!"

[pikelet]

These are important typographical features and I'm fairly sure this is handled by font rendering libraries, not the browser (other than handling the CSS rules), so I can't imagine it's that difficult to implement? Correct me if I'm wrong!

[johncolanduoni]

It’s handled by text shaping libraries (e.g. Harfbuzz in Chrome and Firefox), not font rendering APIs (usually provided by the OS), but you have the right idea.