photo courtsey jak&jilJulia Roitfeld takes Fashionair inside her closet in this video. She names her favorite pieces, models a few outfits, and answers the inevitable question, "What's the best style advice you've gotten from your mom?" Her answer? That it's not just acceptable to mix navy blue and black, but that one should. Even though black and blue combinations dominate the runways - past Vera Wang, Rag & Bone, Armani and Proenza come to mind - there's a hesitation to mix them in real life. In high school, Kate would've said no, but now she loves them together and swears she'll never change her mind. Lauren mixed, though she says everyone thought she was weird, and I honestly can't remember, though now hardly a day goes by that I leave the house without wearing one thing navy and one thing black. It's less a trend question than a classic dilemma, but do you?