Francisco Costa had one concern about Calvin Klein's celebration of Visionaire's new Solar issue at the Standard hotel last night: the dress code. "I thought people might think it was too Puff Daddy," the designer joked about the all-white theme. (He was referring, of course, to the hip-hop impresario's notorious Hamptons party of old.) But Costa needn't have worried. Tyra Banks, Elettra Wiedemann, and Chloë Sevigny all played by the rules, though it took some convincing to get the latter into her ivory Chloé jacket: "I found out about the dress code after I had bought this amazing Comme des Garçons leopard-print dress," said the actress, adding that she thought about wearing the spotted frock anyway but lost the nerve. Not that she would have been alone: Costa, ironically, left his white suit in the car and emerged instead in a white shirt and dark jeans, while Italo Zucchelli, the brand's menswear designer, showed up in a hot pink jacket.

The reason for the mostly adhered-to all-white requirement? Visionaire's Solar issue, which was made in partnership with Calvin Klein, features photographs that change color in sunlight, and Costa and Zucchelli employed similar technology when designing a women's gown and a men's suit in a fabric that goes from white to pink and blue when exposed to UV rays. "They're kind of like those Hypercolor T-shirts that you had when you were a kid," said Harley Viera-Newton, "but much, much chicer."

— Derek Blasberg