已尝试更改Flutter toast中的背景色和文本颜色。但是它不能正常工作

import 'package:flutter/material.dart';

void showToast(BuildContext context, String message, Color backgroundColor, Color textColor) {
  final scaffold = Scaffold.of(context);
  scaffold.showSnackBar(
    SnackBar(
      content: Text(message, style: TextStyle(color: textColor)),
      backgroundColor: backgroundColor,
      duration: Duration(seconds: 2),
    ),
  );
}

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text('Custom Toast Example')),
        body: Center(
          child: ElevatedButton(
            onPressed: () {
              showToast(context, 'Hello, Custom Toast!', Colors.blueGrey[700], Colors.white);
            },
            child: Text('Show Toast'),
          ),
        ),
      ),
    );
}