Anime: blue to green, orange to red to red-pink - really, any colour, cause style > colour

IRL:  brown and black ????
Dyed hair looks weird, cause typically you can see traces of the original hair colour.

And probably cause I had a freak-ish year 6 teacher who dyed her hair orange (on the first day, she had orange hair, orange rimed glasses, orange eyelashes, orange fingernails, orange clothes, orange shoes...)