Theory Vanissa Cami in Navy. - size XS (also in ) Theory Vanissa Cami in Navy. - size XS (also in ) 100% silk. Dry clean only. Crisscross shoulder straps. Asymmetrical hem. THEO-WS823. H0302514. Theory is a visionary concept for modern intelligent fashion forward people. Founded in New York and made by the finest of fabrics, this makes the working everyday person feel powerful, ready to face their day.