sdl draw line section

[sirus20x6]

what is this section for? it just seems to make the rendering of the CA look weird.

    SDL_SetRenderDrawColor(render, 255, 255, 255, 255);
    for (int i = 0; i < MAPWIDTH; i++) {
        SDL_RenderDrawLine(render, i * SCALE, 0, i * SCALE, MAPHEIGHT * SCALE);
    }
    for (int i = 0; i < MAPHEIGHT; i++) {
        SDL_RenderDrawLine(render, 0, i * SCALE, MAPWIDTH * SCALE, i * SCALE);
    }