Looks really nice, the widgets are great and run well on my phone. Is it a real time ray tracer doing the rendering? Still amazes me these days what’s possible in browsers or on a phone.
With these shapes, this can be solved analytically with the equations shown. If this was raytracing, you'd need a lot of rays for such a clean image.
I'm more amazed at the author, it doesn't even kick in the fans on my old MBP 2013! And even then, this is the least praise-worthy feature of the explorable explanation! I find the whole thing quite mindblowing. Congrats to the author.