Jennifer Aniston's hot new look is reportedly down to her fiancé Justin Theroux hiring new celebrity stylist Kate Young.Jennifer Aniston's fiancé is the "driving force" behind her sexy style makeover, it has been claimed.The actress wowed last week when she attended the LACMA Art + Film Gala in a daringly low-cut black Tom Ford dress.Sources revealed the person behind Jennifer's hotter than ever look is Hollywood stylist Kate Young, who her fiancé Justin Theroux has allegedly hired as her new stylist."Justin has been the driving force behind Jen's stunning new look. He introduced her to Kate," a source revealed to British magazine Grazia. "Kate has been encouraging Jen to let go of her more conventional fashion taste and go for more daring outfit choices, like the black Tom ford dress. It's out with the beige and in with the brilliant. Justin loves it."Jennifer's style overhaul has extended to her manicure habits. The actress has recently been spotted with vampish red nail varnish on her fingers, which is unusual for the low maintenance star."For years, Jen has only worn taupe and pale varnish colours because she's been paranoid about her hands," the source explained. "But Kate's told her to stop being silly, even getting her to try out a bright red for the first time to make her look more sexy."