[csswg-drafts] [css-shapes-1] Proposal: Option for the radii of `round` on `<basic-shape-rect>` to resolve percentages against the rectangle itself instead of the reference box (#12598)

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

== [css-shapes-1] Proposal: Option for the radii of `round` on `<basic-shape-rect>` to resolve percentages against the rectangle itself instead of the reference box ==
The border radii specified after the `round` identifier of `<basic-shape-rect>` functions resolve percentage values against the reference box.

However, in many cases authors prefer radius percentages to be resolved against the rectangle itself, i.e. the dimensions computed from the `<basic-shape-rect>` function.

We propose an additional or alternative identifier that changes how those percentages are resolved.

We are not yet sure about good names, so we will go with `self` and `round-self` for the following examples.

For example, the following would create border radii that are always about a third of the related side of the rectangle, leaving the remaining middle third of each side straight, regardless of the `font-size`, and with it the resolved `em` values:
```css
xywh(10mm 5mm 4em 3em round self 33%) /* additional identifier */
xywh(10mm 5mm 4em 3em round-self 33%) /* alternative identifier */
```

Of course `em` values are not a common case. But even with absolute lengths, such percentages are easier to read and understand for authors and maintainers.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/12598 using your GitHub account


-- 
Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config

Received on Wednesday, 13 August 2025 08:21:22 UTC