颤振容器消失

不知道我在这里想念的是什么。希望使容器UI类似于“材料填充文本”字段。只想知道我们是否可以将BorderSide和borderRadius一起使用，或者它们可以分开工作。并且仅使用Container我该如何实现？

import 'package:flutter/material.dart';

final Color darkBlue = Color.fromARGB(255, 18, 32, 47);

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: Container(
            height: 50.0,
            width: 500.0,
            padding: EdgeInsets.symmetric(horizontal: 20.0, vertical: 2.0),
            decoration: BoxDecoration(
              border: Border(
                bottom: BorderSide(width: 2.0, color: Color(0xFFFF7F7F7F)),
              ),
              borderRadius: BorderRadius.only(
                topLeft: Radius.circular(2),
                topRight: Radius.circular(2),
              ),
              color: Color(0xFFBFBFBF),
            ),
            child: const Text('OK',
                textAlign: TextAlign.center,
                style: TextStyle(color: Color(0xFF000000))),
          ),
        ),
      ),
    );
  }
}

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text('Hello, World!', style: Theme.of(context).textTheme.headline4);
  }
}