Handle alpha over 1 (a little bit)

src/builtin/color/hsl.rs

@@ -150,7 +150,7 @@ pub(crate) fn register(f: &mut BTreeMap<String, Builtin>) {
         };
         match arg!(args, 0, "color") {
             Value::Color(c) => Some(Value::Color(c.invert(weight))),
-            _ => todo!("non-color given to builtin function `alpha()`")
+            _ => todo!("non-color given to builtin function `invert()`")
         }
     });
 }

src/builtin/color/opacity.rs

@@ -8,13 +8,13 @@ use crate::value::{Number, Value};
 pub(crate) fn register(f: &mut BTreeMap<String, Builtin>) {
     decl!(f "alpha", |args, _| {
         match arg!(args, 0, "color") {
-            Value::Color(c) => Some(Value::Dimension(c.alpha() / Number::from(255), Unit::None)),
+            Value::Color(c) => Some(Value::Dimension(c.alpha(), Unit::None)),
             _ => todo!("non-color given to builtin function `alpha()`")
         }
     });
     decl!(f "opacity", |args, _| {
         match arg!(args, 0, "color") {
-            Value::Color(c) => Some(Value::Dimension(c.alpha() / Number::from(255), Unit::None)),
+            Value::Color(c) => Some(Value::Dimension(c.alpha(), Unit::None)),
             Value::Dimension(num, unit) => Some(Value::Ident(format!("opacity({}{})", num , unit), QuoteKind::None)),
             _ => todo!("non-color given to builtin function `opacity()`")
         }

src/color/mod.rs

@@ -255,6 +255,7 @@ impl Color {
         } else {
             hue
         };
+
         let saturation = clamp!(saturation, 0, 1);
         let luminance = clamp!(luminance, 0, 1);
         let alpha = clamp!(alpha, 0, 1);
@@ -367,7 +368,12 @@ impl Color {
 /// Opacity color functions
 impl Color {
     pub fn alpha(&self) -> Number {
-        self.alpha.clone()
+        let a = self.alpha.clone();
+        if a > Number::from(1) {
+            a / Number::from(255)
+        } else {
+            a
+        }
     }
 
     /// Change `alpha` to value given

tests/color.rs

@@ -436,3 +436,8 @@ test!(
     "a {\n  color: scale-color(hsl(200, 70%, 80%), $saturation: -90%, $alpha: -30%);\n}\n",
     "a {\n  color: rgba(200, 205, 208, 0.7);\n}\n"
 );
+test!(
+    scale_color_alpha_over_1,
+    "a {\n  color: scale-color(sienna, $alpha: -70%);\n}\n",
+    "a {\n  color: rgba(160, 82, 45, 0.3);\n}\n"
+);