PARIS – In Olivier Rousteing’s office perched on the sixth floor of Balmain’s Paris headquarters, stark white walls and black marble surfaces are coated with perfume bottles, bags, and blown-up campaign imagery. Order rubs shoulders with accumulation in the Balmain style, which Rousteing continues to champion as the house’s creative director since 2011: a silhouette that marries powerful shoulders to body-hugging curves and opulent…