Yeah, that would be a pretty basic feature. I get that he is just showing of some ´out-of-the-box' thinking. But really, it is not something practical.

In the end, he made a TODO-Layout, not a TODO-App. Interesting experiment I suppose, if you are into frontend stuff

A common misconception is that adding JS to HTML (e.g. in forms) _hurts_ accessibility. In fact, foregoing JS in favour of "pure" CSS+HTML can actually be much worse.

Yes, you can create certain interactions with CSS alone but doing so purely for the sake of not using JS is pointless and at worst harmful.

Doesn't take much to add html local storage natively to run this as a web app. Still js free.