fix(css_formatter): don't indent CSS selector when leading comments before

CHANGELOG.md

@@ -33,6 +33,10 @@ our [guidelines for writing a good changelog entry](https://github.com/biomejs/b
 
 ### Formatter
 
+### Bug fixes
+
+- Fix [#4121](https://github.com/biomejs/biome/issues/4326), don't ident a CSS selector when has leading comments. Contributed by @fireairforce
+
 ### JavaScript APIs
 
 ### Linter

crates/biome_css_formatter/src/css/lists/relative_selector_list.rs

@@ -13,17 +13,37 @@ impl FormatRule<CssRelativeSelectorList> for FormatCssRelativeSelectorList {
         let mut joiner = f.join_with(&separator);
 
         for formatted in node.format_separated(",") {
-            // Each selector gets `indent` added in case it breaks over multiple
-            // lines. The break is added here rather than in each selector both
-            // for simplicity and to avoid recursively adding indents when
-            // selectors are nested within other rules. The group is then added
-            // around the indent to ensure that it tries using a flat layout
-            // first and only expands when the single selector can't fit the line.
-            //
-            // For example, a selector like `div span a` is structured like
-            // `[div, [span, [a]]]`, so `a` would end up double-indented if it
-            // was handled by the selector rather than here.
-            joiner.entry(&group(&indent(&formatted)));
+            let has_leading_comments = formatted
+                .node()?
+                .as_css_relative_selector()
+                .and_then(|relative_selector| {
+                    relative_selector
+                        .selector()
+                        .ok()?
+                        .as_css_compound_selector()
+                        .cloned()
+                })
+                .and_then(|computed_selector| computed_selector.simple_selector())
+                .and_then(|simple_selector| simple_selector.as_css_type_selector().cloned())
+                .and_then(|type_selector| type_selector.ident().ok()?.value_token().ok())
+                .is_some_and(|value_token| value_token.has_leading_comments());
+
+            if has_leading_comments {
+                // Computed Selector which contains a leading comments should be formatted without indent.
+                joiner.entry(&group(&formatted));
+            } else {
+                // Each selector gets `indent` added in case it breaks over multiple
+                // lines. The break is added here rather than in each selector both
+                // for simplicity and to avoid recursively adding indents when
+                // selectors are nested within other rules. The group is then added
+                // around the indent to ensure that it tries using a flat layout
+                // first and only expands when the single selector can't fit the line.
+                //
+                // For example, a selector like `div span a` is structured like
+                // `[div, [span, [a]]]`, so `a` would end up double-indented if it
+                // was handled by the selector rather than here.
+                joiner.entry(&group(&indent(&formatted)));
+            }
         }
 
         joiner.finish()

crates/biome_css_formatter/tests/specs/css/declaration_list.css

@@ -34,4 +34,20 @@ a {
 
 a {
     color: red;;;;
+}
+
+.with-comments {
+  /* hello */
+  a,
+  /* world */
+  button {
+    color: blue;
+  }
+}
+
+.without-comments {
+  a,
+  button {
+    color: blue;
+  }
 }

crates/biome_css_formatter/tests/specs/css/declaration_list.css.snap

@@ -42,6 +42,22 @@ a {
 a {
     color: red;;;;
 }
+
+.with-comments {
+  /* hello */
+  a,
+  /* world */
+  button {
+    color: blue;
+  }
+}
+
+.without-comments {
+  a,
+  button {
+    color: blue;
+  }
+}
 ```
 
 
@@ -103,4 +119,20 @@ a {
 a {
 	color: red;
 }
+
+.with-comments {
+	/* hello */
+	a,
+	/* world */
+	button {
+		color: blue;
+	}
+}
+
+.without-comments {
+	a,
+	button {
+		color: blue;
+	}
+}
 ```