Yeah, I can see what you mean, although only a bit of the crust is visible. I would have to suppose that adding some oil to the dough, or even a touch of honey or the like, might increase browning, but that's perhaps Neapolitan heresy. (I'm new to this level of pizza fandom, so I hope you can indulge my ignorance.)
Has this web community developed any consensus about the optimal flour type and brand and a dough formula for a gas oven with pizza stone, given a preference for Naples style pies?