Do containers have a small fixed margin

Keeping Containers Continuously has some margin between them and why aren't they in same color

This the row of 411 containers

   Row(
          mainAxisAlignment: MainAxisAlignment.start,
          mainAxisSize: MainAxisSize.min,
          children: [
            for (int i = 0; i < 411; ++i)
              Container(
                margin: EdgeInsets.all(0),
                width: 1,
                padding: EdgeInsets.all(0),
                height: 100,
                color: Colors.red,
              ),
          ],
        ),

Is this normal in flutter or should anything be changed ?