RED-CARPET COUTURE Listen up, Joan Rivers. Expect actresses to embrace these fashion B’s: baby blue, bustiers, and bare essentials. Celeb stylist Philip Bloch predicts a big bustier blowout: ”Girls… want to feel secure on top and flowy on the bottom.” Watch for pale blue to become the new pink. And to balance all this free-flowing femininity, there will be slits up to there. ”Legs are really big,” says Bloch. Clearly Courtney Love’s already gotten the message…. IN THE LOOP Everyone from Prince William to comeback king Carlos Santana is clamoring for Killer Loop — a new line of urban, edgy eyewear…. COWHIDE HIP Leather and suede are becoming all-season gear — especially in white, camel, lavender, or pink. Gold lame is ”the perfect spring replacement for the pony skirt from fall,” says Jeffrey Kalinsky, owner of upscale retailer Jeffrey New York and Atlanta…. DENIM REDUX From dungarees to dresses, denim is the fabric du ’00 among designers, including John Galliano for Christian Dior. He outfitted Foxy Brown in head-to-toe cowgirl for the opening of Dior’s New York flagship…. TWINKLE, TWINKLE Glittery face powder is all the rage in London. Now Stila’s IPF (illuminating power foundation) will get an evening workout by Cameron Diaz and Natalie Portman, who are planning to wear it to the Golden Globes…. IN THE TRENCHES Old-school trench coats are being refashioned by Louis Vuitton, Yves Saint Laurent, and Marc Jacobs. Stylist Stefan Campbell calls Vuitton’s $1,300 version ”a family heirloom.”