Haha yeah, took some love. I have a scrappy little "framework" that I've been adjusting since I started making interactive posts last year. Writing my interactive widgets feels a bit like doing a game jam now: just copy a template and start compiling+reloading the page, seeing what I can get onto the screen. I've just been using the canvas2d API.

Besides figuring out a good way of dealing with reference frames, the only trick I'd pass on is to use CSS variables to change colors and sizes (line widths, arrow dimensions, etc.) interactively. It definitely helps to tighten the feedback loop on those decisions.

Oh that's way out of my league unfortunately. I wonder if there's a library or something that does something like this.