Re: [csswg-drafts] [css-properties-values-api] `@property` descriptors should be optional whenever possible (#13211)

The CSS Working Group just discussed ``[css-properties-values-api] `@property` descriptors should be optional whenever possible``, and agreed to the following:

* `RESOLVED: make all property descriptors in @property optional`

<details><summary>The full IRC log of that discussion</summary>
&lt;ydaniv> TabAtkins: for now, for reasons we designed in the past, the @property does not give optional default values, all needs to be specified<br>
&lt;ydaniv> ... it proved to be annoyance in practice<br>
&lt;ydaniv> ... it's also been annoying in spec writing<br>
&lt;ydaniv> ... proposal is to make all descriptors in the @property optional as if it was untyped<br>
&lt;kizu> +calc(infinity) to the proposal<br>
&lt;ydaniv> ... I saw nothing but support on the thread<br>
&lt;ydaniv> +1<br>
&lt;miriam> +1 strong support<br>
&lt;kbabbitt> +1, this will also make writing supports-conditions for these easier<br>
&lt;ydaniv> astearns: anyone with reservations? or need more time?<br>
&lt;emilio> q+<br>
&lt;ydaniv> PROPOSED RESOLUTION: make all property descriptors in @property optional<br>
&lt;astearns> ack emilio<br>
&lt;ydaniv> astearns: objections?<br>
&lt;ydaniv> emilio: I think we also do validation on the descriptors, they need to match syntax<br>
&lt;kizu> q+<br>
&lt;ydaniv> TabAtkins: only change that if you specifty a non universal it needs to match syntax<br>
&lt;ydaniv> ... otherwise we keep existing behavior<br>
&lt;astearns> ack kizu<br>
&lt;ydaniv> kizu: +Infinity, only care about interop where authors do this but may start doing something some browsers, but still break in others<br>
&lt;romain> q+<br>
&lt;RRSAgent> I have made the request to generate https://www.w3.org/2026/03/11-css-minutes.html fantasai<br>
&lt;ydaniv> TabAtkins: true, we can see later?<br>
&lt;astearns> ack romain<br>
&lt;ydaniv> astearns: would you like to resolve? or wait?<br>
&lt;ydaniv> kizu: resolve please<br>
&lt;emilio> q+<br>
&lt;TabAtkins> interop is people wrote an *invalid* rule, got a normal custom prop, but now get *some* behavior<br>
&lt;ydaniv> romain: don't see any interop issue, since unregistered is the same as fallbacks we have now<br>
&lt;ydaniv> TabAtkins: [repeating above] ^<br>
&lt;emilio> q-<br>
&lt;ydaniv> kizu: or specify something that was not applied and now stops applying to things that don't match anymore<br>
&lt;romain> +1<br>
&lt;ydaniv> astearns: so are we still trying to resolve and see whether there's a problem?<br>
&lt;ydaniv> ... objections? (again)<br>
&lt;ydaniv> RESOLVED: make all property descriptors in @property optional<br>
</details>


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Received on Wednesday, 11 March 2026 15:27:11 UTC