Never been there on Friday. But you could dress up a little. Very dark and romantic.
Friday's can be both, but mostly casual.
Casual dress is fine, though you may feel underdressed
It is perfectly fine to dress causal, the bar area is always the best location for causal dress unless sitting behind the bar, in which case I have seen formal wear. The dining area you may find more folks dressed up also.
50/50
Both
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