Corrected entry: When we see the Forest Spirit wither the tree that San put on the island in the middle of the lake (in order for Ashitaka's wound to be healed), his face is dark brown, red and white. Later, when the Forest Spirit is walking out to take the lives of the wolf and the boar gods, his face is dark brown, red, white and green. When the Forest Spirit is transforming into the Nightwalker, his face is dark brown, white and beige. Finally, when Ashitaka and San return the Forest Spirit's head at the end of the movie, it's only white and beige.
Chris Moyer Grice
5th Apr 2005
Correction: There are no rules for the color of a magical spirit that can change its shape at will.