Material Design 3引入了新类型的卡片。这些卡片可以通过配置卡片小部件的属性来生成。
要使用此代码示例创建本地项目，请运行：flutter create --sample=material.Card.3 mysample
之后，您可以将日历放在新样式卡上。
Info and code was copied from

import 'package:flutter/material.dart';

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

class CardExamplesApp extends StatelessWidget {
  const CardExamplesApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
          colorSchemeSeed: const Color(0xff6750a4), useMaterial3: true),
      home: Scaffold(
        appBar: AppBar(title: const Text('Card Examples')),
        body: Column(
          children: const <Widget>[
            Spacer(),
            ElevatedCardExample(),
            FilledCardExample(),
            OutlinedCardExample(),
            Spacer(),
          ],
        ),
      ),
    );
  }
}

/// An example of the elevated card type.
///
/// The default settings for [Card] will provide an elevated
/// card matching the spec:
///
/// https://m3.material.io/components/cards/specs#a012d40d-7a5c-4b07-8740-491dec79d58b
class ElevatedCardExample extends StatelessWidget {
  const ElevatedCardExample({super.key});

  @override
  Widget build(BuildContext context) {
    return const Center(
      child: Card(
        child: SizedBox(
          width: 300,
          height: 100,
          child: Center(child: Text('Elevated Card')),
        ),
      ),
    );
  }
}

/// An example of the filled card type.
///
/// To make a [Card] match the filled type, the default elevation and color
/// need to be changed to the values from the spec:
///
/// https://m3.material.io/components/cards/specs#0f55bf62-edf2-4619-b00d-b9ed462f2c5a
class FilledCardExample extends StatelessWidget {
  const FilledCardExample({super.key});

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Card(
        elevation: 0,
        color: Theme.of(context).colorScheme.surfaceVariant,
        child: const SizedBox(
          width: 300,
          height: 100,
          child: Center(child: Text('Filled Card')),
        ),
      ),
    );
  }
}

/// An example of the outlined card type.
///
/// To make a [Card] match the outlined type, the default elevation and shape
/// need to be changed to the values from the spec:
///
/// https://m3.material.io/components/cards/specs#0f55bf62-edf2-4619-b00d-b9ed462f2c5a
class OutlinedCardExample extends StatelessWidget {
  const OutlinedCardExample({super.key});

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Card(
        elevation: 0,
        shape: RoundedRectangleBorder(
          side: BorderSide(
            color: Theme.of(context).colorScheme.outline,
          ),
          borderRadius: const BorderRadius.all(Radius.circular(12)),
        ),
        child: const SizedBox(
          width: 300,
          height: 100,
          child: Center(child: Text('Outlined Card')),
        ),
      ),
    );
  }
}