This so much! I'm surprised that Apple haven't implemented it in Safari so they can use them to match their style elsewhere. I'm not sure what the spec should

This so much! I'm surprised that Apple haven't implemented it in Safari so they can use them to match their style elsewhere. I'm not sure what the spec should be though, maybe bezier curve corners. That would allow asymmetry with "setback" and "control-length" for each side of the corner.