The new Bella Union winery, which opened in late September in St. Helena, begs to be a background for your next Instagram post. Frilly umbrellas that look like they were plucked from a beach in Nice dot the sprawling outdoor patio, and hallways papered in leafy wallpaper lead to sun-soaked rooms filled with saffron-colored velvet booths. On a recent afternoon, the sound of Ariana Grande crooning about her favorite things floated in the crisp autumn air.