BEHIND THE BEST ‘CLUELESS’ LOOKS

First-day-of-school fabulosity

“Amy [Heckerling, the director] loved a school uniform,” May tells The Post. “So how do you transform it to high fashion?” She picked a bright Dolce & Gabbana look to help Cher (Alicia Silverstone, above right) “pop” in the quad. ”Yellow is like sunshine, like, ‘Oh my God, she’s the sunshine of the school,’ ” says May. “And when Alicia put it on it, that was it, that was the one.”

“Dionne was a little savvier,” says May of Stacey Dash’s character (above left). “She was the opposite of Cher, who was kind of prim.” Her schoolgirl look was black and white, with vinyl lapels to go with a vinyl hat. “We did the skirts much shorter on her, a lot of vintage purses and clutches, a lot of texture.”

Date-night chic

“It’s a dress,” says Cher.

Her dad retorts: “Says who?” “Calvin Klein!” The director agreed with Dad’s assessment: “When she put it on, it really looked like lingerie,” says May. “We [added a] sheer Vivienne Tam cover-up.”

Tai’s transformation

“Brittany Murphy was such a delight,” says May. “When we first see her character, it’s like, who’s this ugly duckling? She had the bad hair and baggy clothes, and that gave us a lot to play with. In the end, she’s grown from the grunge [phase] through the overly dressed and primped Cher doll, to find she’s this really cool girl, very down to earth . . . She’s a little boyish but feminine, too.”

The iconic Alaïa

For the popular-kid party in the Valley, the film’s costume maven Mona May was able to pull off a miracle to get this scarlet Alaïa dress off the runway.

“It was so hard to get anything, because nobody was lending clothes back then,” she says. “It was not in our budget to spend a couple thousand on a designer dress! We got a call that we could possibly borrow this, and we totally jumped on it. I don’t think many people knew who Alaïa was before the movie.”