For fall, designers replaced the little black dress with little white ones, but next spring calls for brighter hues. Behold, the little pink dress. Editor in chief of Harper’s Bazaar Glenda Bailey chalks the sudden swing up to “a need for optimism.” “Everyone’s in a ‘think pink’ mood,” she says. But lest you think this translates to frilly and fussy, think again: Today’s LPD is sexy and youthful. Jenni Kayne added thigh-baring slits to a sleek sheath, Cushnie et Ochs dreamed up a pleasingly askew halter, and Kevork Kiledjian emblazoned a snakeskin print onto a body-conscious minidress.