Christina Haack and Josh Hall Rock Couples Costume for '70s-Themed Party

Christina Haack and Josh Hall
Christina Haack and Josh Hall

Christina Haack Instagram

Christina Haack is getting groovy with her fiancé.

The HGTV star, 38, posted a snap on Instagram Sunday of herself and Joshua Hall dressed up for a '70s-themed party. In the photo, the couple posed in a closet in their costumes, Haack wearing a black-and-white mini dress with brown knee-high boots. Holding her close, Hall looked ready for the night in aviators, a mustache, a light blue shirt with a deep V neckline and black pants.

"Heading out to that 70s party 💿 ✌🏼," Haack captioned the snap. She also shared a video to her Instagram Stories of a shirtless Hall showing off some of his costume — and his retro dance moves (below).

RELATED: Christina Haack Shares Romantic Pic of Her 'Disneyland Date' with 'Hunky' Boyfriend Joshua Hall

christina-hack-josh-hall-70s-party-1
christina-hack-josh-hall-70s-party-1

Christina Haack Instagram Stories

The couple's latest outing comes two weeks after they announced their engagement while vacationing in Los Cabos, Mexico, in late September.

Hall popped the question with an emerald-cut ring from Los Angeles-based jeweler Benny and the Gems, which Haack showed off in a smiling selfie from the trip. The relationship milestone came two months after PEOPLE confirmed Hall and Haack were dating in July.

christina haack new ring/ engagement
christina haack new ring/ engagement

christina haack/ instagram

At the time, a source told PEOPLE Haack and her new man had "an immediate, real connection" from the start.

"They've enjoyed getting to know each other one-on-one without outside noise," the source added.

The Christina on the Coast star later revealed she had been seeing the Austin-based realtor since the spring, but kept their relationship secret for months.

"I met Josh when I wasn't in a state of fear or fight-or-flight," she wrote on Instagram in July. "When we met this past spring, the synchronicities hit us so hard and fast they were impossible to ignore. I felt immediately crazy protective over him and wanted to keep him for myself and get to know each other before the tornado (media attention) hit."

Christina Haack Celebrates Josh Hall's Birthday: 'That Teenage Kinda Love'
Christina Haack Celebrates Josh Hall's Birthday: 'That Teenage Kinda Love'

Christina Haack/Instagram

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Since the couple took their relationship public, Haack has shared plenty of their adventures with her followers, including Hall's visits to her new Tennessee home, family trips with her now-fiancé, and vegan lunch dates together.

Just before revealing her engagement, Haack posted a sweet birthday message for Hall on Instagram.

"Happy birthday baby. 🎉 ❤️," she wrote on Sept. 19, sharing a shot of them smiling at the beach. "You give me that teenage kinda love vibe and manly protection. It's a combo for a lifetime of happiness + success. Thank you for reminding me what life and love are like when you put down the technology."