From 45830cd87e8ea471b9c4b79883ba48829d9c22e1 Mon Sep 17 00:00:00 2001
From: Simon Chester <s@scq.me>
Date: Wed, 26 Nov 2025 15:31:09 +1300
Subject: [PATCH] [FEATURE] Parse container queries

---
 CHANGELOG.md                          |  2 ++
 src/Property/AtRule.php               |  2 +-
 tests/CSSList/AtRuleBlockListTest.php |  3 +++
 tests/Unit/Property/AtRuleTest.php    | 22 ++++++++++++++++++++++
 4 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 tests/Unit/Property/AtRuleTest.php

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8978fbb71..1da6a4810 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,8 @@ Please also have a look at our
 
 ### Added
 
+- Support for CSS container queries (#1400)
+
 ### Changed
 
 ### Deprecated
diff --git a/src/Property/AtRule.php b/src/Property/AtRule.php
index 7a00660f8..f5ae475ea 100644
--- a/src/Property/AtRule.php
+++ b/src/Property/AtRule.php
@@ -18,7 +18,7 @@ interface AtRule extends CSSListItem
      *
      * @internal since 8.5.2
      */
-    public const BLOCK_RULES = 'media/document/supports/region-style/font-feature-values';
+    public const BLOCK_RULES = 'media/document/supports/region-style/font-feature-values/container';
 
     /**
      * @return non-empty-string
diff --git a/tests/CSSList/AtRuleBlockListTest.php b/tests/CSSList/AtRuleBlockListTest.php
index 9a725b212..3539463bf 100644
--- a/tests/CSSList/AtRuleBlockListTest.php
+++ b/tests/CSSList/AtRuleBlockListTest.php
@@ -48,6 +48,9 @@ public static function provideSyntacticallyCorrectAtRule(): array
                     }
                 ',
             ],
+            'container' => [
+                '@container (min-width: 60rem) { .items { background: blue; } }',
+            ],
         ];
     }
 
diff --git a/tests/Unit/Property/AtRuleTest.php b/tests/Unit/Property/AtRuleTest.php
new file mode 100644
index 000000000..53793bea8
--- /dev/null
+++ b/tests/Unit/Property/AtRuleTest.php
@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Sabberworm\CSS\Tests\Unit\Property;
+
+use PHPUnit\Framework\TestCase;
+use Sabberworm\CSS\Property\AtRule;
+
+final class AtRuleTest extends TestCase
+{
+    /**
+     * @test
+     */
+    public function blockRulesConstantIsCorrect(): void
+    {
+        self::assertEqualsCanonicalizing(
+            ['media', 'document', 'supports', 'region-style', 'font-feature-values', 'container'],
+            explode('/', AtRule::BLOCK_RULES)
+        );
+    }
+}