Loris Azzaro lived for cocktail hour. Not personally, but professionally. He designed dresses for after dark that glinted with light—crystal embellishments being his signature. Mathilde Castello Branco, the creative director installed at the house last year, took that foundation and turned it into a theme, of sorts, for Spring. She hand-drew a naïve print of tumblers and martini glasses and the words "pchitt" (the sound a Champagne bottle makes when it's uncorked) and "hummm" (the sound you make after your first sip) and used it for a long hostess dress, as well as a poolside maillot-and-shorts set. Pushing the metaphor further, Castello Branco whipped up a party dress in a dégradé of Champagne-colored sequins and embroidered the black tulle back of a long navy silk gown in crystal fireworks. Fireworks at midnight!

Dialing up the whimsy has been part of Castello Branco's MO since she arrived at Azzaro from Lanvin. But she was at her best here when she was playing it straight, as she did with a pair of silk jumpsuits—one in white with crystal-studded tuxedo stripes, and the other in navy, cut like a backless waistcoat. To employ an overused but in this case entirely apt expression, they were seriously chic.