You know when something just clicks? When it just feels right? That was the Calvin Klein spring collection. After seasons of academic explorations of tricky geometric cuts and the types of silhouettes that really only work on gallerists-of-a-certain-age, Francisco Costa nailed it with scintillatingly spare, sensuously subtle silhouettes. Working a palette that focused mainly on shades of white and off-white, with the occasional flash of cobalt, midnight & crimson, Costa gave a master class in creating modern clothing without the slightest whiff of retro. After a Fashion Week that saw predictable uptown/downtown mash-ups and vintage Helmut Lang revivals, Costa’s flawless collection brought the week to an intelligent, original conclusion.