handle ? in value

src/value/parse.rs

@@ -606,7 +606,7 @@ impl Value {
                     Ok(IntermediateValue::Op(Op::Div))
                 }
             }
-            ':' => Err("expected \";\".".into()),
+            ':' | '?' => Err("expected \";\".".into()),
             v if v.is_control() => Err("Expected expression.".into()),
             v => {
                 dbg!(v);

tests/error.rs

@@ -20,6 +20,10 @@ error!(
     "a {@return foo;}", "Error: This at-rule is not allowed here."
 );
 error!(
-    colon_inside_style,
+    colon_inside_value,
     "a {foo: bar: baz;}", "Error: expected \";\"."
-);
+);
+error!(
+    question_mark_inside_value,
+    "a {foo: bar?}", "Error: expected \";\"."
+);