Why do I get a blank white page? Flutter

I am new to Flutter. I get a blank white screen. Is the problem with the code or something else?

My code is as follows:

import 'package:animalsflutter/Splash.dart';
import 'package:flutter/material.dart';

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

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Splash(),
    );
  }
}

And the continuation of the code

import 'package:flutter/material.dart';

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Color(0xff00324B),
      body: Column(
        children: [
          Container(
            width: double.infinity,
            height: double.infinity,
            child: Container(
              child: Image.asset(
                fit: BoxFit.fill,
                "assets/images/hiro.png",
              ),
            ),
          ),
          Stack(
            children: [
              Positioned(
                child: Container(
                  height: 200.0,
                  width: 200.0,
                  decoration: BoxDecoration(
                    color: Colors.blueAccent,
                    border: Border.all(
                      color: Colors.black,
                      width: 2.0,
                    ),
                    borderRadius: BorderRadius.circular(10.0),
                  ),
                  child: Text("signIn"),
                ),
                left: 24.0,
                top: 24.0,
              ),
            ],
          ),
        ],
      ),
    );
  }
}

What could be my problem? And what's the solution? And Could it be a problem with the simulator?