[csswg-drafts] [css-animations] How should relative-length values be interpreted when used in the <keyframe-selector> production in the @keyframes prelude? (#10880)

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

== [css-animations] How should relative-length values be interpreted when used in the <keyframe-selector> production in the @keyframes prelude? ==
Assuming calc() is allowed here (see https://github.com/w3c/csswg-drafts/issues/10879), how should relative-length values be interpreted when used with in it?

The [\<keyframe-selector\>](https://drafts.csswg.org/css-animations-1/#typedef-keyframe-selector) production in the [@keyframes](https://drafts.csswg.org/css-animations-1/#keyframes) prelude is defined via the grammar:

> \<keyframe-selector\> = from | to | [<percentage [0,100]>](https://www.w3.org/TR/css-values-4/#percentage-value)

So, for example, you could have:

```css

@keyframes foo {
  from {
    margin-left: 0px;  
  }
  calc(50% * sign(10em - 2px)) {
    margin-left: 100px;
  }
  from {
    margin-left: 200px;  
  }
}
```

So the question is, what does 10em evaluate to? @font-palette-values contains this text:

> [Math functions](https://www.w3.org/TR/css-values-4/#math-function), such as [calc()](https://www.w3.org/TR/css-values-4/#funcdef-calc), and also [var()](https://www.w3.org/TR/css-variables-1/#funcdef-var), and [env()](https://drafts.csswg.org/css-env-1/#funcdef-env), are valid within descriptor values in a [@font-palette-values](https://www.w3.org/TR/css-fonts-4/#at-ruledef-font-palette-values) rule. They are evaluated within the context of the root element. Relative units are also evaluated within the context of the root element.

but I can't find any similar text for @keyframes.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/10880 using your GitHub account


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Received on Thursday, 12 September 2024 16:09:32 UTC