How best to do fashionable, sexy even, within its confines? ???The key is to balance a demure hemline with a modern print and directional accessories so you look event-appropriate but still fabulous,??? says Holli Rogers, fashiondirector for net-a-porter.com. ???Look to designers such as Prabal Gurung, Christopher Kane and Peter Pilotto for dresses that are both super-chic and ??ber-cool.???