I've seen both
Lee and
Leigh used for both; I always expect
Lee on a boy and
Leigh on a girl. I don't like it for boys in general, though I've got an excellent
Lee nephew. I was at school with a really remarkable girl
Leigh, and she sold me on the name (which I think I'd only use as a mn; it was her mn too, actually, but she always went by it and not by her fn -
Mabel.)