Flutter - Transform scale in center of Container

I'm trying to create a flip effect, but before starting with the animation I'm trying to make the transformation stay in the center of the container.

But even using FractionalOffset(0.5, 0.5) or Center() wrapping the Transform() result remains on the top of the Container, as in the image below.

Could you help me leave it in the center of the container?

import 'package:flutter/material.dart';
void main() {

runApp(new MyApp());

}
class MyApp extends StatelessWidget {

@override

Widget build(BuildContext context) {

return new MaterialApp(

home: new MyHomePage(),

);

}

}
class MyHomePage extends StatelessWidget{

@override

Widget build(BuildContext context) {

return new Scaffold(

appBar: new AppBar(),

body: new Center(

child: new Column(

mainAxisAlignment: MainAxisAlignment.center,

children: <Widget>[

new Container(

alignment: new FractionalOffset(0.5, 0.5),

height: 144.0,

width: 360.0,

decoration: new BoxDecoration(

border: new Border.all(color: new Color(0xFF9E9E9E))

),

child: new Transform(

transform: new Matrix4.identity()…scale(1.0, 0.05),

child: new Container(

decoration: new BoxDecoration(

color: new Color(0xFF005CA9),

),

),

)

)

],

),

),

);

}

}

#flutter