[csswg-drafts] [sizing][quirks] Should `stretch` be affected by percentage height calculation quirk? (#12421)

Loirooriol has just created a new issue for https://github.com/w3c/csswg-drafts:

== [sizing][quirks] Should `stretch` be affected by percentage height calculation quirk? ==
https://quirks.spec.whatwg.org/#the-percentage-height-calculation-quirk

> In [quirks mode](https://dom.spec.whatwg.org/#concept-document-quirks), for the purpose of calculating the [height](https://drafts.csswg.org/css-sizing-3/#propdef-height) of an element element, if [...] the specified value for the [height](https://drafts.csswg.org/css-sizing-3/#propdef-height) property of element is a [`<percentage>`](https://drafts.csswg.org/css-values-4/#percentage-value) [...] the [containing block](https://drafts.csswg.org/css-display-4/#containing-block) of element must be calculated using the following algorithm

It only mentions `<percentage>`, but this was written before CSS Sizing introduced `stretch`.

Arguably, as per https://drafts.csswg.org/css-sizing-4/#stretch-fit-sizing

> - Otherwise, if used in an axis where percentage sizes can resolve to a [definite](https://drafts.csswg.org/css-sizing-3/#definite) value
>     Behaves as 100%, except it sizes the [margin box](https://drafts.csswg.org/css-box-4/#margin-box) regardless of the value of [box-sizing](https://drafts.csswg.org/css-sizing-3/#propdef-box-sizing).

if `100%` would have the quirk, `stretch` should also have it?

Browsers don't agree: Blink and WebKit apply the quirk for `stretch` / `-webkit-fill-avaialble`, while Firefox doesn't for `-moz-available`.

```html
<!-- quirks -->
<div style="height: -moz-available; height: -webkit-fill-available; height: stretch; background: cyan">foo</div>
```

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/12421 using your GitHub account


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Received on Monday, 30 June 2025 21:59:12 UTC