Katie Holmes's signature summer top is the humble button-down. She's worn the essential in sheer chiffon, the strawberry red color trend, and classic white, of course. But if any designer could make Holmes branch out, it's Chanel. On June 8, Chanel's most lightweight tank top gave her Oxfords the evening off at the Tribeca Festival Artists Dinner. The Matthieu Blazy-led label hosted Teyana Taylor, Keke Palmer, Ayo Edebiri, and more at New York City's Tribeca Grill. The dress code?