I /adore/ the hand-drawn styling of this webpage (although the punchline, domain name, and beautiful overengineering are great too). Where did it come from? Is it home grown?
With all these dark patterns nowadays, it's nice to see a 'light pattern'. ;) Instead of using UI to make dubious things seem legit, this is a way to use UI to emphasize things that are not precise.
https://roughjs.com/ is another cool library to create a similar style, although not chart focused.