Stack Widget

 import "package:flutter/material.dart";

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

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: "Hello",
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.brown,
      ),
      home: const FlutterApp(),
    );
  }
}

class FlutterApp extends StatefulWidget {
  const FlutterApp({super.key});

  @override
  State<StatefulWidget> createState() {
    return FlutterState();
  }
}

class FlutterState extends State<FlutterApp> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      drawer: const Drawer(),
      appBar: AppBar(
        title: const Text(
          "Flutter Stack Widget",
          style: TextStyle(fontWeight: FontWeight.bold),
        ),
        centerTitle: true,
        backgroundColor: Colors.grey,
      ),
      body: /*Stack(      */ /*we can get linear pattern from Row and Column.we can get Relative pattern from Stack.*/ /*
              children: [
                Container(
                  width: 200,
                  height: 200,
                  color: Colors.blueGrey,
                ),

                Container(
                  width: 160,
                  height: 160,
                  color: Colors.grey,
                ),
              ],
           ),*/

          Container(
        //Overlap here.To execute Overlapping structure,we can use Stack.
        width: 300,
        height: 300,
        child: Stack(
          children: [
            Container(
              width: 200,
              height: 200,
              color: Colors.blueGrey,
            ),
            Positioned(
              left: 21,
              top: 21,
              bottom: 21,
              right: 21,
              child: Container(
                width: 160,
                height: 160,
                color: Colors.grey,
              ),
            ),
          ],
        ),
      ),
    );
  }
}