[csswg-drafts] [css-sizing] Production for values common to max/min/preferred widths and heights (#13478)

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

== [css-sizing] Production for values common to max/min/preferred widths and heights ==
Could [css-sizing-3](https://drafts.csswg.org/css-sizing-3) please introduce something like `<box-length>` or `<box-dimension> = <length-percentage [0,∞]> | min-content | max-content | fit-content(<length-percentage [0,∞]>) | <calc-size()>`?

With that production, `<'width'>`, `<'height'>`, `<'min-width'>`, `<'min-height'>` could be simplified to `auto | <box-dimension>`, whereas `<'max-width'>`, `<'max-height'>` could become `none | <box-dimension>`. This would make the difference more noticeable. 

[css-sizing-4](https://drafts.csswg.org/css-sizing-4/#sizing-values) can then add `stretch | fit-content | contain` to it.

[css-logical](https://drafts.csswg.org/css-logical-1) refers to `<'width'> and `<'min-width'>` and `<'max-width'>`. Although this is the future-safe way, it feels a bit weird that the _height_ properties also use a _width_ value.

[css-flexbox](https://drafts.csswg.org/css-flexbox/#flex-basis-property) could either keep its `content | <'width'>` value syntax for the `flex-basis` property, or switch to `auto | content | <box-dimension>`.

There may be other places affected.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/13478 using your GitHub account


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Received on Tuesday, 10 February 2026 18:47:17 UTC