If anyone thought Zac Posen’s move from his usual prime-time spot in the big tent to 9 a.m. at the far more intimate Altman Building signaled the twilight of his signature showmanship, they can think again. The morning chez Posen could have been a scene from last night’s party circa 1978, complete with booming music, disco lights and models who shimmied down the pink-carpeted runway. The clothes, too, had the attitude of a partygoing good-time girl: a lot of fun and willing to make some questionable decisions. In a preview, Posen said he was designing with a “late-Seventies New York woman in mind.” He wanted to push a color story and did so with colorblocking for day, setting chalky pink, yellow and purple on structured twill dresses, some with cutouts at the waist, and see-through raincoats worn over Pop Art geometric prints. On one hand, that Mod-ish flavor and kitsch factor, pumped up with lip pins by Yazbukey, was quite charming. On the other, the more shocking combos may not be the easiest sell, realitywise. Less debatable were Posen’s prints — beautiful bold florals custom designed by downtown artist Rosson Crow. Posen put them on kicky pleated skirts and sexy cocktail dresses draped and cut to show skin at the shoulders and back. As for the gowns — a series of sheer silks laden with colorful paillette flowers — they gave the red-carpet formula a delightful dose of youth serum.