Earlier quoted context omitted.
You really should do a blog post about it, the first thing I did after admiring the animation was pull open the inspect panel to see how it was done haha. I would love to read more about it.
So, the technical part isn’t that crazy tbh — as soon as you respect some pretty straightforward principles you should be fine (animate only transform/opacity, favour requestAnimationFrame over setInterval, transitionend/animationend events over setTimeout, …). The complicated part was mostly the “creative” process, ie. how fast should the animation run (some people read, others don’t), what's the appropriate bezier-…
And it does a great job at actually communicating exactly what you wanted it to, which is also an uncommon skill.