[eyelidlessness]

If you want to keep doing this, it’ll save you a whole lot of heartache if you also wholesale prevent margin collapsing. In fact, some people recommended that as a baseline default (I personally find it great for layout but surprisingly mixed for typography).

[wruza]

If only we had <sizer> (or display:sizer) element that could expand, disappear on wrap and not count as a regular child (sort of like a space in a text node)… But that would be so '90s.

[eyelidlessness]

I really think CSS gap is going to cover most of these needs. Adding decorative nodes to the DOM doesn’t seem like a good solution.

[wruza]

decorative nodes to the DOM doesn’t seem like a good solution

Why? You could add the same constraints to the sizer: min, max, flex shrink/grow, put a line or any other shape in it. It wouldn’t even take a separate “display” mode, just make :row-start, :row-end and :row-wrap pseudoclasses to control collapsibility of regular divs at the sides of a container (or whatever styling you need, anything). Instead they feed us yet another crippled special case with these gaps.