6-8 漸層底色

  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        decoration: BoxDecoration(
          gradient: LinearGradient(
            begin: Alignment.topRight,
            end: Alignment.bottomLeft,
            colors: [
              Colors.orange,
              Colors.orange[200],
            ]
          ),
        ),
      ),
    );
  }
}