My first attempt dabbling with CSS subgrid (did you know it’s now supported across the board?? 🤯):
Using arbitrary elements as list markers, with a checklist example where the markers are checkboxes! (+ :has() for different styling when elements are done)
https://codepen.io/leaverou/pen/LYaWNGg
Thanks @fantasai for helping me fix my original attempt, when I still had an inaccurate mental model of how subgrid works.