body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: [
          Center(
            child: Container(
              child: ListView.builder(
                itemCount: 10,
                itemBuilder: (context, index) => Container(
                  height: 200,
                  width: 200,
                  color: Colors.blueGrey[300],
                ),
              ),
              height: 300,
              width: 400,
            ),
          ),
        ],
      ),