And the debut of Issey Miyake's new designer tried literally to take flight with a multi-segment musical and gravity-defying dance performance.

Here are some highlights of Friday's spring-summer 2020 ready-to-wear collections in Paris, including Celine.

HIT ME BALMAIN ONE MORE TIME

Spring found Rousteing in a philosophical mood, posing a fundamental question about fashion.

Contemporary houses constantly mine the 60s, 70s and 80s for inspiration. But are styles from the 34-year-old designer's own youth — the 90s and early aughts — "too recent to consider"?

Cue a display in which Rousteing explored that era and, with no apology, "riffing on the distinctive sounds, spirit and styles of my youth."

Britney Spears' "Baby One More Time" blasted on the soundtrack as gentle, Barbie pink flares — as might befit the costumes of the 90s' pop princess— billowed down the runway at Paris' Opera Garnier.

In contrast to Rousteing's normally austere and structured looks, this 90s musing moved him in a softer direction.

Monochrome and graphic prints graced models sporting 90s shades with hair parted at the side. While, polka-dot tuxedo jackets were constructed with a fluidity that nicely captured the heyday of, say, Janet Jackson.

Rousteing reflected on why recycled trends never encroach into a past more recent than 30 years: "It's perhaps due to a feeling that those looks need a bit more of the filter of time that always helps to smooth out past era's fashion bumps."

While the concept of the show was admirable, in its execution there were some unintended fashion bumps owing to the over-exuberance of certain detailing.

On some asymmetrical looks, the weight of voluminous fabric at the midriff tugged down and produced an unpleasant off-kilter effect.

DIAMONDS ARE THE WORLD'S BEST FRIEND

Fashion is one of the world's most polluting industries, but some houses are launching eco-friendly initiatives of note - some more incremental, some more important.

Chloe has started sending out electronic invitations, in favor of gas-guzzling courier.

And another such move was on display at Balmain's show that featured diamonds incorporated into the spring designs and adornments.

The house proudly claims the sparkle in the show's embellishments were "sustainably created diamonds" and were sourced from the world's only carbon-neutral diamond producer Diamond Foundry.

ISSEY MIYAKE'S FLYING START

Acrobatic ballerinas in parachute-like gowns twirled on one foot as they were hoisted up by a gravity-defying cable.

Models on electric skateboards whizzed past front row guests.

And a circle of models danced around holding hands like the figures in Henri Matisse's 1910 masterpiece "The Dance."

But the highlight by new designer Satoshi Kondo, one that had guests reaching for their cameras, came as Hula Hoops with stretch-material dresses inside descended from the ceiling above three standing models.

A dress slid into place over each model's head — triggering gasps from spectators.

It was the cue for the models to dance to funky music as the material in their gowns bounced like an accordion or a jack-in-the-box, which evoked the house's iconic 1994 Flying Saucer dress.

This last segment showed off the house's famed prowess with techno fabrics.

Yet, Kondo's color-rich designs as a whole didn't feel as fresh as the presentation, nor did he really seem to move the house in a new direction.

Still, there were many beautiful ideas in the spring silhouettes.

The first looks, a series of baby powder coats, had layers of material that folded around the body like origami. While, later in the collection, diaphanous brightly-colored anoraks billowed as they filed past like the cape of an Asian warrior at battle.

These specific looks encompassed what the program notes poetically described as the essential "sense of joy that is primitive and instinctive" in wearing clothes.

ISSEY MIYAKE'S NEW DESIGNER

Iconic Japanese designer Issey Miyake may have retired from the design helm of the house he founded in 1970, but he continues to exert great influence over the Franco-Japanese maison.

Miyake stepped in to appoint Kondo, the house said in a statement: "Mr. Miyake... has made a point of giving talented young designers within the company the opportunity to develop their skills."

But it's unclear why the designer since 2011, Yoshiyuki Miyamae, was replaced. Perhaps it was due to the lukewarm reception of his collections in recent years that some critics felt had lost their edginess.

In a curt explainer, the house said: "Regarding the change, it was a natural decision that came after the last show."

CELINE HAS CHANGED

Smoldering red column structures set the stage for Hedi Slimane's re-branded vision of Celine in an annex near the gilded Invalides.

It was the rebellious designer's third Celine women's collection to date, in which he continued in his clean break-away from its traditional designs.

Spring continued where fall left off — somewhere in the 70s.

Faded denim flares were a key theme in the pared-down designs that featured retro center partings, silk headscarves in leopard print, boho floral gowns and ruffled tan leather boots.

High necks defined the aesthetic of silk shirts that were accessorized by large fedora hats with razor sharp brims.

Smolder it didn't, but the former Saint Laurent designer served up a saleable collection, in which he put his youth-culture-infused stamp on the 74-year-old house.