[Projeto] atividade

return MaterialApp(
        theme: ThemeData(useMaterial3: true),
        home: Container(
            color: Colors.white,
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.center,
              mainAxisAlignment: MainAxisAlignment.spaceEvenly,
              children: [
                Row(
                    mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Container(
                        color: Colors.amber,
                        width: 100,
                        height: 100,
                      ),
                      Container(
                        color: Colors.black,
                        width: 100,
                        height: 100,
                      ),
                      Container(
                        color: Colors.blue,
                        width: 100,
                        height: 100,
                      ),
                    ]),
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                  crossAxisAlignment: CrossAxisAlignment.center,
                  children: [
                    Container(
                      color: Colors.green,
                      width: 100,
                      height: 100,
                    ),
                    Container(
                      color: Colors.pink,
                      width: 100,
                      height: 100,
                    ),
                    Container(
                      color: Colors.red,
                      width: 100,
                      height: 100,
                    ),
                  ],
                ),
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                  crossAxisAlignment: CrossAxisAlignment.center,
                  children: [
                    Container(
                      color: Colors.purple,
                      width: 100,
                      height: 100,
                    ),
                    Container(
                      color: Colors.orange,
                      width: 100,
                      height: 100,
                    ),
                    Container(
                      color: Colors.cyanAccent,
                      width: 100,
                      height: 100,
                    ),
                  ],
                ),
              ],
            )));