Set transparent color of a child to recreate this layout in Flutter

Question

i'm currently taking a course where i need to recreate this layout: Layout design

I'm struggling to set that transparent yellow color on the second box in the center of the scaffold. This is my code:

class myApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(scaffoldBackgroundColor: Colors.teal),
      home: Scaffold(
        body: SafeArea(
          child: Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: <Widget>[
              Container(
                color: Colors.red,
                height: double.infinity,
                width: 100.0,
              ),
              Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: <Widget>[
                    Container(
                      color: Colors.yellow,
                      height: 100.0,
                      width: 100.0,
                    ),
                    Container(
                      width: 100.0,
                      height: 100.0,
                      color: Colors.yellowAccent,
                    )
                  ]),
              Container(
                color: Colors.blue,
                height: double.infinity,
                width: 100.0,
              )
            ],
          ),
        ),
      ),
    );
  }
}

Thank you for the help.

Answer 1

Just use with Colors.yellow.withOpacity(0.3) for the second box

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(scaffoldBackgroundColor: Colors.teal),
      home: Scaffold(
        body: SafeArea(
          child: Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: <Widget>[
              Container(
                color: Colors.red,
                height: double.infinity,
                width: 100.0,
              ),
              Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: <Widget>[
                    Container(
                      color: Colors.yellow,
                      height: 100.0,
                      width: 100.0,
                    ),
                    Container(
                      width: 100.0,
                      height: 100.0,
                      color: Colors.yellow.withOpacity(0.3),
                    )
                  ]),
              Container(
                color: Colors.blue,
                height: double.infinity,
                width: 100.0,
              )
            ],
          ),
        ),
      ),
    );
  }
}