Handle number passed to invert()

src/builtin/color/hsl.rs

@@ -150,11 +150,13 @@ pub(crate) fn register(f: &mut BTreeMap<String, Builtin>) {
     decl!(f "invert", |args, _| {
         max_args!(args, 2);
         let weight = match arg!(args, 1, "weight"=Value::Dimension(Number::from(100), Unit::Percent)) {
-            Value::Dimension(n, u) => bound!("amount", n, u, 0, 100) / Number::from(100),
+            Value::Dimension(n, u) => bound!("weight", n, u, 0, 100) / Number::from(100),
             v => return Err(format!("$weight: {} is not a number.", v).into()),
         };
         match arg!(args, 0, "color") {
             Value::Color(c) => Ok(Value::Color(c.invert(weight))),
+            Value::Dimension(n, Unit::Percent) => Ok(Value::Ident(format!("invert({}%)", n), QuoteKind::None)),
+            Value::Dimension(..) => return Err("Only one argument may be passed to the plain-CSS invert() function.".into()),
             v => return Err(format!("$color: {} is not a color.", v).into()),
         }
     });

tests/color.rs

@@ -258,6 +258,14 @@ test!(
     "a {\n  color: invert(white);\n}\n",
     "a {\n  color: black;\n}\n"
 );
+test!(
+    invert_number,
+    "a {\n  color: invert(10%);\n}\n"
+);
+// test!(
+//     invert_number_casing,
+//     "a {\n  color: iNveRt(10%);\n}\n"
+// );
 test!(
     invert_weight_percent,
     "a {\n  color: invert(white, 20%);\n}\n",