AppBar and background colors not showing in Flutter project

I am following a YT video (https://www.youtube.com/watch?v=C-fKAzdTrLU&t=1407s), which is a 1 hour Flutter tutorial. I am using VSCode and Android Studio on a Mac, creating a main page with a button that links to another with an image. The links work, but my main page is black when it should be white with a blue app bar on top.

import 'package:flutter/material.dart';import 'home_page.dart';void main() {  runApp(const MyApp());}class MyApp extends StatelessWidget {  const MyApp({super.key});  @override  Widget build(BuildContext context) {    return MaterialApp(      debugShowCheckedModeBanner: false,      theme: ThemeData(primarySwatch: Colors.blue),      home: const HomePage(),    );  }}class RootPage extends StatefulWidget {  const RootPage({super.key});  @override  State<RootPage> createState() => _RootPageState();}class _RootPageState extends State<RootPage> {  int currentPage = 0;  @override  Widget build(BuildContext context) {    return Scaffold(      appBar: AppBar(        title: const Text('One Hour Youtube'),      ),      body: const HomePage(),      floatingActionButton: FloatingActionButton(        onPressed: () {          debugPrint('Floating Action Button');        },        child: const Icon(Icons.add),      ),      bottomNavigationBar: NavigationBar(        destinations: const [          NavigationDestination(icon: Icon(Icons.home), label: 'Home'),          NavigationDestination(icon: Icon(Icons.person), label: 'Profile'),        ],        onDestinationSelected: (int index) {          setState(() {            currentPage = index;          });        },        selectedIndex: currentPage,      ),    );  }}

I typed out the same code, used ChatGPT as well and checked for any error messages.