For Sin City's L.A. premiere, Alba donned a blue Zac Posen cocktail dress that evoked some serious old-school glamour. The hourglass-shaped number featured a strapless bustier top, demure hemline, and a structured bodice — all common themes for Posen's ultra-feminine designs. The little fin details at her hip are a more badass take on the peplum's gentle flare, and help the retro-inspired frock steer clear of looking dated. Alba also kept things simple in the beauty department with beachy waves and a muted makeup palette.
The actress provides the perfect middle ground for those of us who love retro style, but don't want to go full-on Dita Von Teese with it. As for the look's copy-ability? It's safe to assume we'll be sporting some tousled hair and a bombshell silhouette at our next cocktail hour.