我尝试创建一个按钮的边框，但我得到这个错误："未定义命名参数" border ""我知道小部件已更新，但我找不到未标识该参数的原因。
代码如下：

const ChooseOptionScreen({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          Container(
            alignment: Alignment.center,
            child: FractionallySizedBox(
              widthFactor: 0.4,
              child: OutlinedButton(
                border: OutlineInputBorder(borderRadius: BorderRadius.circular(20.0)),
                style: ButtonStyle(
                  backgroundColor: MaterialStateProperty.all(Colors.blue),
                  textStyle: MaterialStateProperty.all(const TextStyle(color: Colors.white)),
                ),
                onPressed: () {
                  Navigator.pushNamed(context, '/login');
                },
                child: const Text('Login'),
              ),
            ),
          ),
          const SizedBox(height: 10),
          Container(
            alignment: Alignment.center,
            child: FractionallySizedBox(
              widthFactor: 0.4,
              child: OutlinedButton(
                border: OutlineInputBorder(borderRadius: BorderRadius.circular(20.0)),
                style: ButtonStyle(
                  backgroundColor: MaterialStateProperty.all(Colors.green),
                  textStyle: MaterialStateProperty.all(const TextStyle(color: Colors.white)),
                ),
                onPressed: () {
                  Navigator.pushNamed(context, '/register');
                },
                child: const Text('Register'),
              ),
            ),
          ),
        ],
      ),
    );
  }
}```