Flutter: neu

main.dart

class NeumorphicContainer extends StatelessWidget {
  // ...
  
  // New property, will store overridden color
  // if passed from outside
  final Color color;

  NeumorphicContainer({
    Key key,
    this.child,
    this.bevel = 10.0,
    // We can't initiailize it with default background here, unless we
    // know it aforehead and don't bother with dynamic themes.
    this.color,
  })  : this.blurOffset = Offset(bevel / 2, bevel / 2),
        super(key: key);

  @override
  Widget build(BuildContext context) {
    // We'll use either provided color, or color from theme.
    final color = this.color ?? Theme.of(context).backgroundColor;

    return Container(...);
  }
}