Re: [csswg-drafts] [css-borders] `border-radius` with a circular edge (#6467)

I think these percentages units would raise some complications. Like, presumably they wouldn't be `<percentage>` since they wouldn't make sense in other properties. But authors may expect `calc(25%min + 1px)` or even `calc(25%min + 25% + 1px)` to work, so would need to add a bunch of productions like `<something>`, `<length-something>`, `<percentage-something>`, `<length-percentage-something>`.

I think it's simpler to just make it a keyword separate from the `<length-percentage>`, e.g. width a width of 200px and height of 100px,
-  `border-radius: 10% min` is like `10px`
-  `border-radius: 10% max` is like `20px`
-  `border-radius: calc(50px - 10%) min` is like `40px`

On the other hand, this raises some questions when using multiple values, but I guess the grammar could be `<length-percentage [0,∞]>{1,4} [ min | max ]? [ / <length-percentage [0,∞]>{1,4} [ min | max ]? ]?`. Then
- `border-radius: 1% 2% 3% 4% min` uses `min` for all percentages, so `1px 2px 3px 4px`
- `border-radius: 1% 2% 3% 4% / 5% 6% 7% 8% min` uses `min` for the y components, so `2px 4px 6px 8px / 5px 6px 7px 8px`

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Received on Saturday, 18 October 2025 22:44:52 UTC