问颤振:如何着色Sizedbox (不使用容器)

EN

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home : Scaffold(
        appBar: AppBar(
          title : const Text('this is title'),
        ),
        body : const SizedBox(
          width : 200,
          child: DecoratedBox(
              decoration: BoxDecoration(
                color : Colors.red,
              ),
          ),
        ),
        bottomNavigationBar: (
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
            children: const [
              Icon(Icons.favorite),
              Icon(Icons.home),
              Icon(Icons.settings)
            ],
          )
        ),
      ),
    );
  }
}