Re: [csswg-drafts] [css-backgrounds-3][css-borders-4] The shape of box-shadow should be a circle for a box with border-radius:50% and big spread (#7103)

> What if we embraced that and made shadow spread behave exactly like outline/stroke

@noamr Can you clarify what you mean with "outline/stroke"? Is it just the discontinuous algorithm from https://drafts.csswg.org/css-backgrounds-3/radius-expansion ? That is, if the radius is zero keep it zero, otherwise increase it by the spread distance.

Outer outlines should just follow the same algorithm as outer shadows. Now I'm seeing that it's not the case for Blink, it kept the old discontinuous algorithm for outlines, while it adopted the new one from the spec for shadows and `overflow-clip-margin`. That seems nonsensical, everything should use the same algo.

The last case in your image shows the problem: the inner element only has a negligible 1px border radius for the bottom right corner, while the shadow has a big radius. So that doesn't seem continuous at all.

Of course feel free to argue that the discontinuous algorithm may be preferable. But the discontinuity is a bit undesirable (that's why the spec adopted the current algorithm), so we need to be clear.

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Received on Monday, 25 August 2025 21:30:39 UTC