A fantastic tool! I couldn't help but notice when I did the first exercise that the way of live editing did distract me from observing the code deeper than fiddling with the actual values needed.

So if one would now ask me how do I do a full-yellow box I would not know how to do it from scratch. However, I would know that the RGBA values were 1, 1, 0 and 1, which is the most important part to learn.

That's why I think there is a lot of work to be done when making proper abstractions around this for human programmers in the future.

This is however just an observation on my part, I think this is definitely the way to go forward. Making learning more interactive just makes so much sense.