support @at-root inside media query inside style rule

README.md

@@ -29,7 +29,7 @@ That said, there are a number of known missing features and bugs. The notable fe
 ```
 indented syntax
 @forward and more complex uses of @use
-complex uses of @at-root
+media queries with @at-root
 @media query merging
 media queries with @import
 / as a separator in color functions, e.g. rgba(255, 255, 255 / 0)

src/output.rs

@@ -327,7 +327,13 @@ impl Css {
                 }))]
             }
             Stmt::Return(..) => unreachable!("@return: {:?}", stmt),
-            Stmt::AtRoot { .. } => unreachable!("@at-root: {:?}", stmt),
+            Stmt::AtRoot { body } => body
+                .into_iter()
+                .map(|r| self.parse_stmt(r))
+                .collect::<SassResult<Vec<Vec<Toplevel>>>>()?
+                .into_iter()
+                .flatten()
+                .collect(),
             Stmt::Keyframes(k) => vec![Toplevel::Keyframes(k)],
             Stmt::KeyframesRuleSet(k) => {
                 let KeyframesRuleSet { body, selector } = *k;

tests/at-root.rs

@@ -107,6 +107,26 @@ test!(
     }",
     "a {\n  color: red;\n}\n\na {\n  color: red;\n}\n"
 );
+test!(
+    at_root_inside_media,
+    "@media screen {
+      @at-root a {
+        color: red;
+      }
+    }",
+    "@media screen {\n  a {\n    color: red;\n  }\n}\n"
+);
+test!(
+    at_root_inside_media_inside_style_rule,
+    "b {
+      @media screen {
+        @at-root a {
+          color: red;
+        }
+      }
+    }",
+    "@media screen {\n  a {\n    color: red;\n  }\n}\n"
+);
 error!(
     #[ignore = "we do not currently validate missing closing curly braces"]
     missing_closing_curly_brace,