When that signature, rainbow-colored hair of the 1980s made a comeback, it was wilder than ever.

Layers of crazy pink transitioning to purple, blue and green now pepper Instagram feeds and pop up in everyday life.

But what about rainbow hair “lite”? Something prettier, more wearable, designed for the woman who secretly adored the whimsy of that Starbucks Unicorn Frappuccino but can’t rationalize a mermaid-hued mane at her 9-to-5 office?

Colorist Rachel Bodt of the New York salon Cutler suggests a “beautiful, lush and sophisticated” alternative: seashell hair — as in the gentle iridescence of a shell’s interior.

“This hair is for someone who wants color that’s interesting but (for whom) the really funky colors won’t work,” Bodt said.

Here’s how she does it:

Bleach and tone

Pastels show up best on pale-blond hair. To get there, your colorist will do what’s called a double process.

Bleaching removes the natural pigment from the hair, then toning returns color to your strands to create the right shade of blond.

A double process can look good on all skin colors, from dark to fair.

“It’s like red hair that way,” Bodt said. “You just have to find the right tone.”

Her rule of thumb: Match the blond tone to your skin’s undertones. Golden undertones look best with creamy shades; cool skin tones look good paired with platinum-white hair.

“The paler the hair, the better it absorbs these colors,” Bodt said. “It’s like painting a white wall versus painting a pale-yellow wall.”

Ideally, a big bleach job is better left to professionals.

Very curly hair tends to be dryer and more delicate because of its spiral structure. It might not be able to handle a complete bleach job.

“You should have your colorist do a test patch,” Bodt said. “If the hair loses its elasticity or breaks, you won’t be able to bleach it.”

Women with textured hair or those who simply don’t want to do a double process can highlight some pieces, or curls, a light blond.

Layer in color

Bodt used Redken Shades EQ, a demi-permanent gloss — “meaning it has both ammonia and dye, so it deposits the color inside the hair shaft,” she said.

It’s not as durable as regular permanent color, lasting a few weeks at best.

“The colors are also dusty, which helps the overall look be more muted,” she said. “And since I’m using real hair color, not Manic Panic, which is just pigment, the colors are more natural rather than cartoonish.”

Bodt painted rose onto the roots and pulled the color through to the ends of pieces scattered throughout the hair.

“The key to this look is leaving a lot of the blond visible,” she said. “That way the pastels don’t hide or distract from the beautiful blond. It’s a complement.”

After rinsing the rose gloss, Bodt added diluted rose and violet glosses all over. The effect of this step is more transparent, leaving a light tint to the hair.

This “ties everything together, so it’s not just pink roots and then suddenly blond hair,” she said.

She finished the look by painting on ribbons of violet throughout.

“If you really want to go for it, you can do a semi-permanent rose or violet all over the hair,” Bodt said. “If your hair is highlighted, the dusty pastel shade will pick up more the palest blond hair, but your whole head will have a beautiful, dusty, pastel cast.”

In very curly hair, the roots aren’t always visible. So Bodt takes a more customized approach.

“You have to look at how the curls fall around the face,” she said, “and paint those that are most flattering — perhaps around the cheekbones or at the ends of some curls.”

Style with texture

Leave the hair textured, Bodt advises.

Don’t use a flat iron or blow-dry it pin straight. Because the color is woven throughout, it will be hidden if the hair has no movement and volume.

“Seashell hair is actually the perfect summer color,” Bodt said, because we’re all straightening and blow-drying less anyway.

“And you don’t have to maintain it. The color just washes out, so you can do it once or twice and then let your blond base color come through.

“It’s like jewelry for the hair — sparkle without commitment.”