Uh oh, I just paid for one of their pre-paid, non-refundable, reservations at 110 a pop. Are they casual enough to allow for shorts?
I'm not a big fan of hipster cool either, as it too comes off as a bit pretentious to me.
Well, keep in mind that I'm only a data point of one. Since you're already committed I would just say go with an open mind and prepare to be blown away. It happens.
As for shorts, lots of replies on TA that indicate the restaurant won't care a bit. To be on the safe side I would call first.
Hopefully you're reservation isn't for today - scorcher outside, at least for here, and for those of us stuck working in offices without air conditioning.