[css-houdini-drafts] [css-properties-values-api] (#1162)

Crissov has just created a new issue for https://github.com/w3c/css-houdini-drafts:

== [css-properties-values-api] ==
> [`@property`](https://drafts.css-houdini.org/css-properties-values-api-1/#at-ruledef-property) rules require a [`syntax`](https://drafts.css-houdini.org/css-properties-values-api-1/#descdef-property-syntax) and [`inherits`](https://drafts.css-houdini.org/css-properties-values-api-1/#descdef-property-inherits) descriptor;
> if either are missing, the entire rule is invalid and must be ignored.

This requirement seems *very* unlike any other declaration list in CSS.

~~~~ css
@property --partial { }
@property --partial { syntax: "*"; }
@property --partial { syntax: "<length>"; }
@property --partial { inherits: true; }
~~~~
should be equivalent to
~~~~ css
@property --partial {
  syntax: "<length>";
  inherits: true;
}
~~~~

> The [`initial-value`](https://drafts.css-houdini.org/css-properties-values-api-1/#descdef-property-initial-value) descriptor is optional only if the syntax is the [universal syntax definition](https://drafts.css-houdini.org/css-properties-values-api-1/#universal-syntax-definition), otherwise the descriptor is required;
> if it’s missing, the entire rule is invalid and must be ignored.

Particularly with multiple custom property names per #1058, which will frequently just differ in `initial-value`, these requirements combined would still lead to needless repetitions. 

Please view or discuss this issue at https://github.com/w3c/css-houdini-drafts/issues/1162 using your GitHub account


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Received on Wednesday, 3 December 2025 15:49:01 UTC