There's no dress code, though I wouldn't show up in sandals, a tank top, and shorts. The attire you'll see most is upscale trendy. Most of the men will be in business casual and the women in dressesl. That said, there were also those in clean jeans and sneakers who didn't look out of place. I think for the most part, if you dress decent, you'll fit right in.
Shelong Yang has it right. No dress code, but business casual is the best way to go.
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