If Cannes is the big dawg of the film festival world, where the stars wear couture ballgowns and selfie sticks are banned, then think of the Tribeca Film Festival as its cool indie brother, with a red carpet crawling with Saturday night inspo. And Zoë Kravitz, Dakota Fanning and Amber Heard all looked particularly flawless at this weekend's festival. Not relying on pretty dresses alone, these three nailed the whole look from top to toe. Find out how…