When I first started high-school, literally EVERYTHING was regulated. Hair-ties had to be black, grey or raspberry pink thin bands, and nothing else, so alice bands were banned. Same with socks, which were ankle high, and only white socks were allowed to be knee high. All girls had to wear skirts to the knee and you couldn't even buy trousers. Shoes had to be black lace ups and the heels were frequently measured to make sure you weren't cheating on the "2cm or less" rule. Juniors couldn't even walk through certain entrances as the seniors, and even the seniors were banned from the main doors, which were reserved for staff and 6th formers. Oh, and if you were caught with say, a t-shirt on under your school shirt, or a non-school sweatshirt on over it, that was against the rules too.
You could wear silver or gold stud earrings, no hoops, nothing dangly and no other jewelry unless you got a letter from your parents confirming it was for religious reasons. No makeup and no 'unnaturally dyed hair'. So you could dye your hair, provided nobody noticed you'd dyed it.
It changed a lot in the time I was there, like the hair tie thing, and we protested and were allowed trousers eventually, but I think they still use the door system, and the make-up and jewelry still seems pretty strict.
And this was all since the turn of the millenium at a non-religious middle-class school.
Happy days!