Re: [csswg-drafts] [css-color-4] [css-color-5] Mixing with `transparent` seems broken in implementations (#8612)

Have been looking at this a bit more.

As far as I can tell any mix with a color that has `0` alpha, (including, but not limited to `transparent`) will always just be the other color for `rectangular orthogonal` color spaces.

For `cylindrical polar` color spaces the colors will only interpolate the hue's, all other components will always just come from the other color.

When mixing with `transparent` the `hue` happens to be a missing/powerless component and `hue` isn't premultiplied / unpremultiplied

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I think the main issue here is a lack of test coverage in WPT and some implementation bugs.

Missing tests :
- `color-mix` with `transparent` in both `rectangular orthogonal` and `cylindrical polar` color spaces
- `color-mix` with several colors with `0` `alpha` in both `rectangular orthogonal` and `cylindrical polar` color spaces
- 


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Received on Sunday, 19 March 2023 09:36:17 UTC