allow escapes at the start of selectors

src/stylesheet.rs

@@ -157,7 +157,7 @@ impl<'a> StyleSheetParser<'a> {
         while let Some(Token { kind, .. }) = self.lexer.peek() {
             match kind {
                 'a'..='z' | 'A'..='Z' | '_' | '-' | '0'..='9'
-                | '[' | '#' | ':' | '*' | '%' | '.' | '>' => rules
+                | '[' | '#' | ':' | '*' | '%' | '.' | '>' | '\\' => rules
                     .extend(self.eat_rules(&Selector::new(), &mut Scope::new())?),
                 &'\t' | &'\n' | ' ' => {
                     self.lexer.next();

tests/selectors.rs

@@ -507,3 +507,8 @@ test!(
     "a, %b {\n  color: nth(&, 2);\n}\n",
     "a {\n  color: %b;\n}\n"
 );
+test!(
+    escape_at_start_of_selector,
+    "\\61 {\n    color: red;\n}\n",
+    "a {\n  color: red;\n}\n"
+);