Author here.

I'm the rendering lead for Chrome, and know quite a lot about how it works. I also recently wrote a series of articles about the new rendering architecture of Chromium, see here:

https://developer.chrome.com/blog/renderingng/

Pavel is a professor at the University of Utah and has extensively studied CSS from an academic point of view. He also has a lot of experience teaching the material and making it accessible to students.

https://mobile.twitter.com/chrishtr says "Rendering lead for Chrome", so at least one of the authors seems to do this professionally.

More about his team’s work: https://www.chromium.org/teams/rendering