So far I'm going for bay, but does she have a dark stripe down the top of her back? That's a sign of a dun if she does. But so far I'm going for bay still.
Actually, a LOT of bays have "dorsal stripes"... although they aren't true dorsal stripes - just a form of countershading. Almost any color can have them (my palomino has one), but you most commonly see them on bays.
I see a very dark bay who has faded in the sun. POSSIBLY even a severely sun faded black, although I doubt that. The light face, light tail feathers, and light mane (over the withers) scream sun fading to me.
Browns wouldn't have a completely light face. They would look more like this: