I've been writing interactive math and computer science articles at https://growingswe.com/blog. The past few months, I have been obsessed with interactive learning experiences and currently building https://math.growingswe.com for learning probability.
I really like https://math.growingswe.com nice job! I did the foundations page. I will work through some more lessons and give you some feedback later this week. I am also working on some math projects. Take a look at my other comment in this Ask HN.