Ben Affleck's new film Live By Night has a truly absurd cast. Affleck himself, the film's director, stars as a Prohibition-era gangster, surrounded by an array of actors including Elle Fanning, Zoe Saldana, Brendan Gleeson, Anthony Michael Hall, and Sienna Miller. Miller, whose last credit was the Burberry holiday video The Tale of Thomas Burberry, tries her hand at a period piece yet again (she has a thing for retro roles), but her red carpet looks since Live By Night has premiered have been anything but outmoded. It can't be an accident that, for a New York screening of the film, Miller swapped her usual English It girl (read: Burberry) look for one of New York's most prominent exports — Proenza Schouler. December has only just taken root but the red carpet's most prominent icons are all already looking ahead to spring. And rightly so, since the Fall 2017 season is fast approaching, and with it, a whole new crop of looks to choose from.

Sienna Miller in Proenza Schouler at the special screening of Live By Night at the Metrograph theater in New York, New York, December 2016.

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Who: Sienna Miller.

When: Tuesday, December 13.

Where: A special screening of Live By Night with Elle Fanning and Ben Affleck at the Metrograph theater in New York, New York.

What: A yellow, red, and blue crocheted long-sleeved midi dress by Proenza Schouler with feather trim around the hem from the Spring 2017 collection with peep-toe black shoes.

Why: From time to time, Sienna Miller trades in her Burberry digs for something a little less British. For a screening of her new film, Live By Night, at New York's hip new Metrograph theater, she elected a color-blocked Proenza Schouler Spring 2017 design. The latest collection from Jack McCollough and Lazaro Hernandez was rife with geometric blocks of color and unexpected textures; for her red carpet photo opp, Miller essentially borrows the look wholesale from the runway. Her sandals are a bit more delicate than the ones spotted on the runway, and she eschews the intricate earrings — but these are a minor adjustment. With swaths of primary colors, the midi dress doesn't want for much in the way of accessories; it's already got its own feather wreath around the hem of the skirt, after all.

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