formatting support for @position-try (for #3773)

CHANGELOG.md

@@ -77,6 +77,10 @@
     }
     ```
 
+* Formatting support for the `@position-try` rule ([#3773](https://github.com/evanw/esbuild/issues/3773))
+
+    Chrome shipped this new CSS at-rule in version 125 as part of the [CSS anchor positioning API](https://developer.chrome.com/blog/anchor-positioning-api). With this release, esbuild now knows to expect a declaration list inside of the `@position-try` body block and will format it appropriately.
+
 ## 0.21.3
 
 * Implement the decorator metadata proposal ([#3760](https://github.com/evanw/esbuild/issues/3760))

internal/css_parser/css_parser.go

@@ -1102,6 +1102,10 @@ var specialAtRules = map[string]atRuleKind{
 	// Defining before-change style: the @starting-style rule
 	// Reference: https://drafts.csswg.org/css-transitions-2/#defining-before-change-style-the-starting-style-rule
 	"starting-style": atRuleInheritContext,
+
+	// Anchor Positioning
+	// Reference: https://drafts.csswg.org/css-anchor-position-1/#at-ruledef-position-try
+	"position-try": atRuleDeclarations,
 }
 
 var atKnownRuleCanBeRemovedIfEmpty = map[string]bool{

internal/css_parser/css_parser_test.go

@@ -1539,6 +1539,14 @@ func TestAtRule(t *testing.T) {
   }
 }
 `, "")
+
+	// https://drafts.csswg.org/css-anchor-position-1/#at-ruledef-position-try
+	expectPrinted(t, `@position-try --foo { top: 0 }`,
+		`@position-try --foo {
+  top: 0;
+}
+`, "")
+	expectPrintedMinify(t, `@position-try --foo { top: 0; }`, `@position-try --foo{top:0}`, "")
 }
 
 func TestAtCharset(t *testing.T) {