Unify web and ggez tour examples 🎉

src/color.rs

@@ -0,0 +1,19 @@
+/// A color in the sRGB color space.
+#[derive(Debug, Clone, Copy, PartialEq)]
+#[allow(missing_docs)]
+pub struct Color {
+    pub r: f32,
+    pub g: f32,
+    pub b: f32,
+    pub a: f32,
+}
+
+impl Color {
+    /// The black color.
+    pub const BLACK: Color = Color {
+        r: 0.0,
+        g: 0.0,
+        b: 0.0,
+        a: 1.0,
+    };
+}