I'm installing faux wood blinds in my home. I prefer the outside mount because it looks better on my windows, however the molding is a weird design. The head casing and side casing don't meet at a nice 90 degree angle. Instead, there is joining piece that connects the two casings at a 45 degree angle. The joining piece is small, maybe an inch. But if I'm hanging blinds, where should have them start: at the top of the head casing or the top of the side casing?