dark method

Implementation

ButtonStyle dark() {
  return copyWith(
    backgroundColor: WidgetStateProperty.all(
      Color(0xFF343a40),
    ), // Bootstrap dark black
    foregroundColor: WidgetStateProperty.all(Colors.white),
    shape: WidgetStateProperty.all(
      RoundedRectangleBorder(borderRadius: BorderRadius.circular(4.0)),
    ),
  );
}