Eighteen years ago the world became widely aware of the plaid yellow suit, the white minidress, and an overload of argyle. With Clueless's 1995 motion-picture release, Cher, Dionne, and Amber brought these average-seeming clothes to life, establishing themselves as fashion icons.

On the film's 18th birthday, it seems appropriate to pay tribute to its lasting legacy and the woman behind its style: Mona May. Clueless was, surprisingly, her first feature film—and thanks to the 60 costumes she created for Cher alone, Vogue and WWD named it the "fashion movie of the year." The New York Times called it "best enjoyed as an extended fashion show." But May, speaking this week with The Daily Beast, says she never could have guessed how much the fashion from the film would hold up today.

Born in India to European parents, May’s style aesthetic has an international perspective—she studied fashion in Paris, Milan, and Germany—which she considered important when translating high fashion (including Calvin Klein, Alaïa, and Jean-Paul Gaultier) into the wardrobes of the characters. Aiming to break the mold of the overtly grunge style of L.A. high schoolers at the time—which she calls “very Kurt Cobain, Gwen Stefani”—she and writer-director Amy Heckerling sought to develop a seemingly realistic era filled with Dr. Seuss–like top hats and furry backpacks. Transforming grunge into something modern and girly, Cher and her friends became the idolized version of Beverly Hills high schoolers in their knee-high stockings, little berets, and Mary Janes.

Although Clueless overaccentuated—and at some points even imagined—what the typical rich Beverly Hills teen was like, the costumes and the world made it seem, in some small way, actually normal. May explained, “I think the overall fun of the film was ... really diving into this Beverly Hills world—the guys with the low pants, the different factions of the stoners, the Donald Faison with all the cool black guys, the hipsters ... every person that was on the screen really had a look. The whole story was, I think, much more realistic even though it was not really what was happening at the moment.”

Cher laughs that while her life may look like a Noxzema commercial, it's actually “way normal.” And some version of the norm is kind of exactly what it became.

While the characters in the film may have been caricatures in a sense, the style that May and Heckerling created for the girls was actually ahead of its time. The simplicity of the white strapless Calvin Klein dress that Cher wears on her first date with "disco-dancing, Oscar Wilde–reading" Christian, the sleek lines of the red mini Alaïa she’s dressed in as she gets held up in the Valley, and the minimalism of her collection of twin sets, argyle sweaters, and miniskirts are evident, in some form or another, in recent fashion. Now the ’90s have been revived in the form of crop tops, leather miniskirts, and plaid—with runways adding a more modern and sophisticated twist to the Clueless girls' wardrobes.

As May put it, “There’s [an outfit] that’s really great, too—the white T-shirt with the sheer overlay. It’s like, you look at Barney’s catalog right now, and it’s in there. It’s still very, very modern."

Since ’90s fashion was totally buggin'—read: definitely not focused on simplicity—“It was a lot of scrunchies, layers, kind of bad prints, plaids, and leftovers from the ’80s”—May and Heckerling focused on creating style that both would express the characters' over-the-top personalities and would in a way be timeless. The Calvin Klein mini was their take on the “classic, simple little slip,” that little black (or white) dress that became popularized with earlier feminine films like Breakfast at Tiffany’s. May describes Cher's outfit—the leather miniskirt and cream twin set—while she's in her father's office as "beautiful" and something "the girl in Beverly Hills today would be wearing," albeit maybe more Vivienne Westwood–esque with strands of pearls.

Similarly, the water-bottle holders with Chanel-like chains that were created for the girls to clutch while they’re standing against the wall during the gym class scene even received Karl Lagerfeld's stamp of approval, with a version later ending up on his runway. "There can’t be something more flattering than that," May says. 

With its iconic, fashion-savvy quotes—think “This is an Alaïa ... it’s like a really important designer,” or “Lucy, where’s my white collarless shirt from Fred Segal?!”—Clueless’s style legacy continues to influence fashion today. Versace took cues from Cher’s yellow plaid suit on their Fall/Winter 2013 runway, in 2010 Calvin Klein remade Cher's iconic dress, and California cool label Wildfox created an entire collection paying homage to the film, aptly named We’re the Kids in America. But, while it may seem that May and Heckerling sought to create a film for the ages, they never would have guessed the success it would later become.

“We were pioneering something without setting out to pioneer in a sense," says May. "I don’t think we were thinking, like, oh, my God, we’re doing this, it’s going to be the biggest hit, and every girl is going to be wearing these clothes. It was never really that intention.”