Cf. observablehq.com/@harrislapiroff/cistercian-numbering Also see talk.observablehq.com/t/4570

Oh wow your approach is much more elegant than mine 😅

I code-golf tidied this one a bit further, and added some rounded corners: observablehq.com/d/d404eb04f83a2ffb

Nice golfing! Merged :) And I like your recreation of the original graphic Harris!

if you make changes, don't forget to re-publish :)