The problem isn't Sepia - I'm getting the same margins on mafSilver in FF12 on Snow Leopard.
It might be Firefox, though - when I open Camino 2.1.2 or Safari 5.1.7 on the same machine, I don't get the margins.
Discretion is the better part of valor.
If I helped lynch you, you deserved it.
Retired from playing for the foreseeable future.