main.dart

// Rounded border glitch
  
import 'package:flutter/material.dart';

final Color darkBlue = Color.fromARGB(255, 18, 32, 47);

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: MyWidget(),
      ),
    );
  }
}

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container(
          width: 200,
          height: 200,
          decoration: BoxDecoration(
                color: Colors.white,
                borderRadius: BorderRadius.circular(200),
                border: Border.all(color: darkBlue, width: 4),
              )
        );
  }
}