main.dart

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(
      title: 'Flutter4fun',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const HomePage(),
    );
  }
}

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.blueGrey,
      body: LayoutBuilder(
        builder: (context, constraints) {
          return GridView.count(
            crossAxisCount: constraints.maxWidth < 800 ? 1 : 2,
            childAspectRatio: 1.7,
            padding: const EdgeInsets.all(16),
            crossAxisSpacing: 16,
            mainAxisSpacing: 16,
            children: const [
              Card(),
              Card(),
              Card(),
              Card(),
            ],
          );
        }
      ),
    );
  }
}