如何在Flutter中处理不同屏幕尺寸上的定位元素(在Stack中)？

import 'package:flutter/material.dart';

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Stack(
        children: [
          Positioned(
            top: MediaQuery.of(context).size.height * 0.1,
            left: MediaQuery.of(context).size.width * 0.2,
            child: Container(
              width: 100,
              height: 100,
              color: Colors.red,
            ),
          ),
          Positioned(
            top: MediaQuery.of(context).size.height * 0.3,
            left: MediaQuery.of(context).size.width * 0.4,
            child: Container(
              width: 100,
              height: 100,
              color: Colors.blue,
            ),
          ),
        ],
      ),
    );
  }
}