[csswg-drafts] [css-color-adjust-1] Clear expectations for properties affected by forced colors in animation keyframes? (#4176)

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

== [css-color-adjust-1] Clear expectations for properties affected by forced colors in animation keyframes? ==
Suppose an author defines an animation outside of the `forced-colors` MQ, declaring property values in its keyframes which are [typically reverted](https://www.w3.org/TR/css-color-adjust-1/#forced-colors-properties) in forced color modes: https://jsfiddle.net/9ezqLfmt/

Prior implementations in MS browsers would allow this animation to run with the property values as specified by the author outside of the MQ, only updating the forced system colors for the given properties at the end of the animation. So in the given example, the `background-color` animates from red to yellow, then finally is computed to the value of the `Window` system color.

This is a bit jarring for the user. The better experience is probably to ensure that whatever UA guidance is given for the properties in [Properties Affected by Forced Colors Mode](https://www.w3.org/TR/css-color-adjust-1/#forced-colors-properties) applies to these properties inside of animation keyframes as well. Perhaps this is a given, but it might be worth explicitly calling out in the spec to avoid multiple interpretations or author confusion (given historical implementations).

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/4176 using your GitHub account

Received on Tuesday, 6 August 2019 19:32:49 UTC