Container Widget

 import 'package:flutter/material.dart';

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

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

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

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text(
          "DashBoard",
          style: TextStyle(fontWeight: FontWeight.bold),
        ),
        centerTitle: true,
        backgroundColor: Colors.grey,
      ),
      body: Container(
        width: double.infinity,
        height: double.infinity,
        color: Colors.blue.shade50,
        child: Center(
          child: Container(
            width: 100,
            height: 100,
            //color: Colors.blueGrey,
            decoration: BoxDecoration(
                color: Colors.blueGrey,
                //borderRadius: BorderRadius.only(topLeft: Radius.circular(21), bottomRight: Radius.circular(21))
                //borderRadius: BorderRadius.all(Radius.circular(21))
                //borderRadius: BorderRadius.circular(21),

                border: Border.all(width: 7, color: Colors.black),
                boxShadow: const [
                  BoxShadow(blurRadius: 7, color: Colors.grey, spreadRadius: 5)
                ],
                shape: BoxShape.circle),
          ),
        ),
      ),
    );
  }
}