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[css-conditional-5] Add env() for use with @supports #13676

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tabatkins merged 1 commit into from
Mar 24, 2026
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[css-conditional-5] Add env() for use with @supports #13676

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21 changes: 20 additions & 1 deletion css-conditional-5/Overview.bs
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Original file line number Diff line number Diff line change
Expand Up @@ -118,12 +118,13 @@ Extensions to the ''@supports'' rule</h2>
<dfn>&lt;supports-feature></dfn> = <<supports-selector-fn>>
| <<supports-font-tech-fn>> | <<supports-font-format-fn>>
| <<supports-at-rule-fn>> | <<supports-named-feature-fn>>
| <<supports-decl>>
| <<supports-env-fn>> | <<supports-decl>>
<dfn>&lt;supports-decl></dfn> = ( [ <<declaration>> | <<supports-condition-name>> ] )
<dfn>&lt;supports-font-tech-fn></dfn> = font-tech( <<font-tech>> )
<dfn>&lt;supports-font-format-fn></dfn> = font-format( <<font-format>> )
<dfn>&lt;supports-at-rule-fn></dfn> = at-rule( <<at-keyword-token>> )
<dfn>&lt;supports-named-feature-fn></dfn> = named-feature( <<ident>> )
<dfn function lt="env()" for="@supports">&lt;supports-env-fn></dfn> = env( <<ident>> )
</pre>

: <<supports-condition-name>>
Expand Down Expand Up @@ -156,6 +157,12 @@ Extensions to the ''@supports'' rule</h2>
The result is true if the UA
<a href="#dfn-support-named-feature">supports the named feature</a>
provided as an argument to the function.

: <<supports-env-fn>>
::
The result is true if the UA
<a href="#dfn-support-env">supports the environment variable</a>
provided as an argument to the function.

<h3 id="support-definition-ext">
Extensions to the definition of support</h3>
Expand Down Expand Up @@ -217,6 +224,13 @@ Named conditions</h4>
<dfn export for=CSS id="dfn-supports-condition-name">support a named condition</dfn>
when the related [=named supports condition=] returns true.

<h4 id="support-definition-env">
Environment variables</h4>

A CSS processor is considered to
<dfn export for=CSS id="dfn-support-env">support an environment variable</dfn>
if the <<ident>> is a supported [=environment variable=].

<h2 id="when-rule">
Generalized Conditional Rules: the ''@when'' rule</h2>

Expand Down Expand Up @@ -2045,6 +2059,11 @@ Changes since the <a href="https://www.w3.org/TR/2024/WD-css-conditional-5-20241

<ul>
<!-- to 21 October -->
<li>
Extended [=supports queries=] to express [=environment variable=] capabilities
via ''@supports/env()''.
(<a href="https://github.com/w3c/csswg-drafts/issues/3576">#3576</a>)
</li>
<li>Clarified that the last @supports-condition in document order wins
(<a href="https://github.com/w3c/csswg-drafts/issues/12973">#12973</a>)
</li>
Expand Down