Stars can't get enough of Alo Yoga's trendy athliesure. Instagram/marthastewart48; Instagram/kyliejenner; Instagram/halleberry It’s Alo Yoga’s birthday — and shoppers are the ones getting a gift. The trendy athleisure label’s annual Aloversary sale just kicked off, bringing 30% off everything on the site. All you’ll need to do is sign up to become a member of the brand’s rewards program, which is totally free. With so much on sale, we’ve highlighted 10 favorites below — from Kylie Jenner’s workout set to the sweatpants Lena Dunham called “perfect.” Alo 7/8 High-Waist Airlift Legging Alo Alo’s sleek got a lift in popularity from celebrity fans like Hailey Bieber, who owns them in at least four colors . Kendall Jenner, Olivia Wilde, Alix Earle, Bella Hadid and Sydney Sweeney (to name but a few) each have at least one pair.…