[csswg-drafts] [css-color-6] Does color-layers() need a color interpolation method (or similar)? (#13254)

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

== [css-color-6] Does color-layers() need a color interpolation method (or similar)? ==
(I realize CSS Color 6 is marked "not ready for implementation", but, perhaps it's still worth discussing?)

As far as I have been able to figure out, the compositing operations defined in https://www.w3.org/TR/compositing-1/ don't give any guidance on what color space blend-mode operations should use, and implementations blend content using whatever backing store format they happen to be using, historically sRGB, but could be anything.  I suppose one could argue https://www.w3.org/TR/css-color-4/#interpolation implies that blending should happen in Oklab, but no implementations I am aware of do that.

While that is problematic, what I am actually trying to determine is how `color-layers()` function tentatively defined in CSS Color 6 (https://drafts.csswg.org/css-color-6/#color-layers) should behave. 

Unlike `mix-blend-mode`, there is no backing store to fallback on. 

My first instinct is that color-layers() needs a color interpolation method like color-mix(), but I am not clear if polar colors can be used meaningfully with the Porter-Duff operators.

Am I missing something and this is actually well defined? 



Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/13254 using your GitHub account


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Received on Saturday, 20 December 2025 18:45:49 UTC