[csswg-drafts] [css-color-hdr-1] Clarify parsing and serialization of `hdr-color()` (#13597)

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

== [css-color-hdr-1] Clarify parsing and serialization of `hdr-color()` ==
https://drafts.csswg.org/css-color-hdr-1/#hdr-color-function

  > The two headroom values must not be the same

1. What should happen if the two headroom values are the same? Should the function be invalid?

2. In `color-hdr(0 xyz-d65 1.2 0 0, xyz-d65 1.2 0 0)`, are they the same value? Should the default value be `0` when omitted, as is suggesting the [CSSWG discussion](https://github.com/w3c/csswg-drafts/issues/11616#issuecomment-2654776232) that led to the resolution to add `color-hdr()`?

3. I think its `<color>` components should serialize as resolved in #10328 but since the corresponding spec edits are still pending, could it be clarified in this issue?

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I suspect that `hdr-color() = color-hdr(...)` is intentional. But that seems confusing, imo.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/13597 using your GitHub account


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Received on Wednesday, 4 March 2026 08:07:12 UTC