Re: [csswg-drafts] [css-gaps-1]: Change the initial value for insets property to be 0 (#13137)

I constructed a few more examples this morning to double-check that `0` made sense as the default for all insets now that we have `overlap-join`: https://codepen.io/kevinbcmu/pen/bNwrrqg

(Note that I've simulated `overlap-join` using `calc()` in these mockups and that yields some undesired decoration extensions when combined with `rule-visibility-items: between`; I've raised this in the code review for implementation. This case has also firmly convinced me that `overlap-join` is, in fact, needed.)

The case the prompted this investigation was `inset: 0` combined with `rule-visibility-items: around` which I admit is a bit ugly:

<img width="374" height="378" alt="Image" src="https://github.com/user-attachments/assets/58b801a9-b6d5-4460-b6c4-cfecc17a4049" />

However, in the context of the other cases on that page, I believe we should stick with the current status quo.
- The motivation for changing the default inset to `0` still stands: If the default were `overlap-join`, authors would not see any difference when shifting from `rule-break: normal` to `rule-break: intersection` unless they also change `rule-inset`.
- Reintroducing `auto` to fix that one case would, in my opinion, be too magical. Taking the other cases into account, I don't see a sensible and predictable set of if-elses to specify for it to follow.

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Received on Friday, 20 March 2026 17:17:51 UTC