No, it's not thin. Only at the center parting, which is no surprise as it's a part. See those masses of bundled curls at the nape of her neck? You can't have thin hair and such lengthy tresses all at once. Besides, a human's scalp isn't pink. Unless shaved, it should be the same hue as the rest of his/her skin, only paler. Which it is. Even if it were pink, and could "bleed" through, it couldn't change the tint of one's hair to a dark red/scarlet/burgundy, it would be lightened to something more like a platinum rose/dull redash.
Zaijian,
Tiger