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

The algorithm for superellipse spread is actually a bit simpler than the ^3 reduction and I think works better for all curvatures including ordinary rounded corners and circles.

- It takes the spread and converts it into a scale+translate matrix that would map the original rect into the rect-after-spread. This might be a non-uniform scale if it's a non-square rect.
- it applies that matrix to the original shape created by the rect+curved corners.

This works well for shadows because a shadow is not supposed to change the shape, only transform a copy of it in (pseudo-)3d space.
I was not part of the previous takes on this but I wonder if we could rethink applying this algorithm to rounded rects without corner-shape.


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Received on Wednesday, 2 July 2025 20:56:10 UTC