allow + in selectors

src/stylesheet.rs

@@ -155,7 +155,7 @@ fn is_selector_char(c: char) -> bool {
     c.is_alphanumeric()
         || matches!(
             c,
-            '_' | '-' | '[' | '#' | ':' | '*' | '%' | '.' | '>' | '\\'
+            '_' | '-' | '[' | '#' | ':' | '*' | '%' | '.' | '>' | '\\' | '+'
         )
 }
 

tests/selectors.rs

@@ -525,3 +525,8 @@ test!(
     "ℓ {\n  color: red;\n}\n",
     "@charset \"UTF-8\";\nℓ {\n  color: red;\n}\n"
 );
+test!(
+    plus_in_selector,
+    "+ {\n  color: &;\n}\n",
+    "+ {\n  color: +;\n}\n"
+);