darken method
Darkens the color with the given integer percentage amount. Defaults to 10%.
Implementation
Color darken([final int amount = 10]) {
if (amount <= 0) return this;
if (amount > 100) return Colors.black;
final HSLColor hsl = HSLColor.fromColor(this);
return hsl
.withLightness(math.min(1, math.max(0, hsl.lightness - amount / 100)))
.toColor();
}