I think a hidden gem here is at the end, when it says 'what's cool is, I can now do stuff like.. green Bart, colorless Bart'

That's something I've often thought is a real ace in the sleeve of CSS and also SVG, that ability to basically have artistic parameters as code and change them, animate them, etc.

Obviously you can do that offline so to speak in image applications, but the iteration time is hugely longer, stuff like caching becomes a problem, and you definitely can't automate it based on runtime inputs etc. It's almost like having that image application running in the browser, rendering whatever changes you need in real time.