Snippet of the color changes in reflection.app guide cards

color_util.dart

const double minLightness = 0.30;
const double maxLightness = 0.55;
const double lightnessRange = maxLightness - minLightness;
const int numberOfColors = 3;

/// The top card gradients logic
///
/// Generate a list of gradient colors based on the provided [originalColor].
/// This function generates three gradient colors by adjusting the lightness of the [originalColor].
List<Color> generateGradientColors(Color originalColor) {
    final hslColor = HSLColor.fromColor(originalColor);
    final lightnessValues = generateRandomLightnessValues(numberOfColors);

    final gradientColors = lightnessValues.map((lightness) {
      final newHSLColor = hslColor.withLightness(lightness);
      return newHSLColor.toColor();
    }).toList();

    return gradientColors;
  }

List<double> generateRandomLightnessValues(int count) {
    final random = Random();
    return List.generate(
      count,
      (index) => (random.nextDouble() * lightnessRange + minLightness).clamp(0.0, 1.0),
    );
  }
```

/// The bottom color is gotten from this function
///
/// Adjusts the lightness of the provided [color] based on the theme brightness of the [context].
/// If the theme is dark, it decreases the lightness; otherwise, it increases the lightness.
Color adjustLightnessBasedOnTheme(Color color, BuildContext context) {
  final hslColor = HSLColor.fromColor(color);
  final isDarkTheme = context.isDark;
  final adjustedLightness = isDarkTheme ? 0.1 : 0.95;

  return hslColor.withLightness(adjustedLightness).toColor();
}