Flutter 主题在 Windows 上没有改变

我还是个初来乍到的人，所以我决定学习一个教程，教我如何使用Flight制作一个Spotify克隆版.他指定了一个定制的黑色主题，当他运行代码时，它确实是一个黑色主题，但当我运行它时，它仍然是白色的.我最初以为我在某个地方打了一个字，所以我复制了他的代码，但这并没有改变任何事情.

I get this result

This is the result I want to get

我的main.dart文件

import 'package:flutter/material.dart';

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

class Spotify extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Spotify UI',
      debugShowCheckedModeBanner: false,
      darkTheme: ThemeData(
        brightness: Brightness.dark,
        appBarTheme: const AppBarTheme(backgroundColor: Colors.black),
        scaffoldBackgroundColor: const Color(0xFF121212),
        backgroundColor: const Color(0xFF121212),
        primaryColor: Colors.black,
        accentColor: const Color(0xFF1DB954),
        iconTheme: const IconThemeData().copyWith(color: Colors.black),
        fontFamily: 'Montserrat',
        textTheme: TextTheme(
          headline2: const TextStyle(
            color: Colors.white,
            fontSize: 32.0,
            fontWeight: FontWeight.bold,
          ),
          headline4: TextStyle(
            fontSize: 12.0,
            color: Colors.grey[300],
            fontWeight: FontWeight.w500,
            letterSpacing: 2.0,
          ),
          bodyText1: TextStyle(
            color: Colors.grey[300],
            fontSize: 14.0,
            fontWeight: FontWeight.w600,
            letterSpacing: 1.0,
          ),
          bodyText2: TextStyle(
            color: Colors.grey[300],
            letterSpacing: 1.0,
          ),
        ),
      ),
      home: Shell(),
    );
  }
}

class Shell extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          Expanded(
            child: Row(
              children: [
                Container(
                  height: double.infinity,
                  width: 280.0,
                  color: Colors.green,
                ),
                // PlaylistScreen
              ],
            ),
          ),
          Container(
            height: 84.0,
            width: double.infinity,
            color: Colors.blue,
          ),
        ],
      ),
    );
  }
}