Daylight-saving time may be getting longer, but spring dresses certainly aren't.

In fact, they're getting much, much shorter — looking less like dresses and more like long shirts. And, as sexy "American Idol" runner-up Katharine McPhee, actress/party girl Lindsay Lohan and fashion plate Mischa Barton have proven recently, they barely cover up the ladies who dare to wear them.

"The biggest real trend is the spring minidresses, with an empire waistline that you wear with tights underneath," said Jacqui Stafford, executive style director at Shape magazine. "It's a transition from the colder months into the warmer."

Indeed, the minidress, a staple of the 1960s, is now tinier and more risqué than ever.

Tiny, swingy frocks in all shapes, patterns and colors dotted the spring catwalks, and they showed no signs of leaving during New York's Fall Fashion Week last month.

Photo Essay: Minidresses On and Off the Runway

Click HERE to read FOXNews.com's Fall Fashion Preview

But, warned Stafford, fashionistas should tread gingerly on the trend, especially if they're elderly — like in their 30s.

Actress Tori Spelling, 33, made the unfortunate choice to make a fashion statement recently when she was extremely pregnant. Let's put it this way: It wasn't a good move. If beauty magazines haven't yet put the Spelling photos in their "fashion don't" columns, they certainly should.

"You never wear a bum-grazing mini unless you're a 20-year-old cutie from Miami," Stafford said. "Minis should be age-appropriate … If you're below 30, you can get away with it, but over 30, I'd think very carefully about the rest of your ensemble."

More specifically, the rest of the ensemble should include opaque tights or leggings worn underneath, preferably with flats or platform shoes so the outfit doesn't reveal too much or scream "tramp."

"If you wear it with flats, it makes the look less in-your-face," said Style.com Executive Editor Nicole Phelps. "With a heel, it begs the question, is this look too young for you or too sexy? A platform or wedge rather than a high heel or stiletto gives it a retro feel rather than a tarty feel."

Phelps said the minidress look for spring is what's known as the "trapeze dress," which mimics the outline of, not surprisingly, a trapeze — in a boxy, trapezoid shape that's narrower at the top and wider at the bottom and has a high waist or no waist at all.

So-called T-shirt dresses are another rendition of the mini. A third version is the flapper dress, complete with gold or silver fringe, though that's not likely to make it off the runways and onto real-world streets.

In fact, minis won't wind up on most ordinary girls and women in the short-short styles we see on models and actresses — unless the wearers are very bold, very young or both.

Longer versions that stop a couple of inches above the knee rather than grazing the top of the thigh are what's on display this season in boutiques, retail chains and on real women.

"You never see exactly what's on the runway," Stafford said. "Very few women would have the courage to pull off a really mini mini."

The teensy dresses are part of the larger "mod" fad that's hip this season. Metallic fabrics, silver sequins and beading, bright, neon colors and big, geometric prints seem to have flown in from outer space and landed on shirts, skirts, dresses, shoes and bags.

"There are a lot of space-age influences," Phelps said, pointing out that Gucci's spring collection included pieces with spacy, honeycomb-patterned beading, and gold "C3PO leggings" were featured in the Balenciaga line.

Among the bright colors that are the most glaring this season is an eye-popping, sunshiny yellow. Think Reese Witherspoon, who wore a dazzling, knee-length, citron yellow Nina Ricci dress at the Golden Globes and is on the cover of this month's Harper's Bazaar in a yellow Valentino dress and matching poofy shrug.

"I felt like I looked (more) different than I've ever looked," Witherspoon told Harper's, relaying the story of a Nina Ricci designer saying to her, "I see you in yellow."

But if an outfit all in yellow isn't your thing, you can follow the fad by accessorizing with a pineapple-colored bag, belt, necklace or pair of shoes, style gurus suggest.

Bright colors aren't just showing up in clothes but in makeup, too. Electric blue eye shadow is another hot spring trend, back in all its tacky glory from the '80s, when women wore it with almost feverish persistence.

Other key looks this season: ballerina flats, which continue to be huge; wedge shoes with peep toes; and fun, retro hair accessories like headbands and turbans.

But just as BMW's Mini was the ooh-ahh car of a few seasons ago, this spring's head-turner is the mini of the fashion world. Celebs and commonfolk alike who are bold enough to "go there" should just make sure to do it with finesse.

"It's really important if you're wearing a mini that the rest of the outfit is very sophisticated," Stafford said. "No plunging neckline. You're not a hooker, and you don't want people to wonder, where do I look?

"But if you've got great legs," she coaxed, "wear it."