Oh, prom. An American tradition that's meant different things to different people, and with vibe shifts over the decades.

The 7 Little Johnstons star is preparing for senior prom in ... the lacy mermaid sky blue dress with silver and white embellishments and the spicy tangerine neon orange sequin design.

While celebrities like Selena Gomez and Demi Moore were dressed in the most striking, classy gowns, prom ... dress features ...