PARIS (AP) — It was more than just another fashion show in the City of Lights. Louis Vuitton’s latest extravaganza on Paris’ most famous street, the avenue des Champs-Elysées, transformed an iconic 19th-century Art Nouveau space into an evolving artwork. As guests entered, they encountered an ephemeral installation — a vast, expanding balloon structure that melded with the walls. But as avant-garde as it was, the installation’s plastic, coupled with an autumnal heatwave, had some attendees likening it to a fashionable yet sweltering greenhouse.