[csswg-drafts] Clamping values and additive animation (#12648)

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

== Clamping values and additive animation ==
There is no useful form of additive animation that disallows negative Keyframe values. SVG spec defers clamping for opacity:
https://www.w3.org/TR/SVG11/implnote.html#RangeClamping

CSS does not. This needs to be specified. Firefox and Chromium behavior differ on additive opacity animation. Firefox (only recently) disallows clamping, while Chromium permits useful behavior:
https://bugzilla.mozilla.org/show_bug.cgi?id=1984925

This needs to be extended to include all clamped property values, including but not necessarily limited to width, height, and the new size shorthand.
https://github.com/w3c/csswg-drafts/issues/12645

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/12648 using your GitHub account


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Received on Sunday, 24 August 2025 21:30:39 UTC