I'm not sure when little girls started wearing $72 workout pants—probably shortly after their moms adopted a uniform of $98 yoga pants. Anyway, there's now a destination for upscale activewear for girls, and of course it is brought to us by the company that made premium yoga gear a way of life: lululemon athletica. Introducing ivivva athletica, which opened today at Mall of America. The store, located across the hall from lululemon—first floor, south side near Macy's—is a holiday pop-up, with potential legs. Several ivivva stores have already opened in Canada and more than a half dozen are currently being tested across the U.S. ivivva plays to dancer, skaters and gymnasts—athletes already accustom to paying a pretty penny for costuming. There's plenty of general activewear as well, in girls' sizes 4 to 14.