alt Hacker NewsIt used cssparser and html5ever from the Servo project, and it used the Taffy library for flexbox and CSS grid layout algorithms which isn't officially part of Servo but is used by Servo.
I'd estimate that's a lot less than 60% of the "actual work" though.
My bad, I was misinformed, thanks for correcting me, I thought it used the renderer, not just the parser. Thats honestly way better than what I thought.