Blonde hair

I know it's a minor thing but why didn't Demi Moore keep her natural raven locks for this film. She doesn't really look right as a blonde (although I suppose it might have given her an ethereal quality); her colouring doesn't fit, or maybe it was just a bad dye job. She's still an extremely beautiful woman (and she's aged remarkably well compared to some of her contemporaries) but unlike some brunettes she doesn't suit blonde hair.