def draw():
    screen.fill((0, 0, 0))
    
    grid_x_count = 20
    grid_y_count = 15
    cell_size = 15
    
    screen.draw.filled_rect(
        Rect(
            0, 0,
            grid_x_count * cell_size, grid_y_count * cell_size
        ),
        color=(70, 70, 70)
    )