colorScheme: ColorScheme(
  primary: Colors.red, // focus
  onPrimary: Colors.black,
  primaryVariant: Colors.orange,

  background: Colors.red,
  onBackground: Colors.black,

  secondary: Colors.red, //float action button
  onSecondary: Colors.white,
  secondaryVariant: Colors.deepOrange,

  error: Colors.black,
  onError: Colors.white,

  surface: Colors.white, // AppBar
  onSurface: Colors.black, //icons, inputs

  brightness: Brightness.light,
),