[csswg-drafts] [css-color-5] What is the computed value of light-dark(none, none)? (#13866)

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

== [css-color-5] What is the computed value of light-dark(none, none)? ==
The [spec says](https://drafts.csswg.org/css-color-5/#typedef-light-dark-image) that `none` in `light-dark()` produces a fully transparent image equivalent to `linear-gradient(transparent)`, but for properties which do not accept `none` or where `none` means something else than a transparent image, a computed value of `none` will not round-trip.

Examples:

list-style-image:

```css
list-style-image: light-dark(none, none); /* replaces the marker */
list-style-image: none; /* does not replace the marker */
```

Registered syntax `<image>`:
```css
@property --img {
  syntax: "<image>";
  inherits: false;
  initial-value: linear-gradient(transparent);
}

.transparent {
  --img: light-dark(none, none); /* valid */
}
.none {
  --img: none; /* invalid */
}
```
What should be the computed value of `light-dark(none, none)`?

@tabatkins @CGQAQ

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/13866 using your GitHub account


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Received on Thursday, 30 April 2026 08:30:38 UTC