Her white frock from the Cushnie et Ochs spring 2013 collection calls the slinky silhouettes and plunging necklines of the '70s to mind, but with 21st-century updates—like the midi-length ...

Known for the rise of disco, bold colors, patterns, and peasant dresses, the '70s brought forth many trends we absolutely love. Think about it for a sec. Paisley, plaid, crochet and prairie-style ...

In the photo, the couple posed in a closet in their costumes, Haack wearing a black-and-white mini dress with brown knee ... "Heading out to that 70s party ," Haack captioned the snap.