Hailey Bieber kept it sleek and flirty in a soft pink Alexander Wang gown, turning heads with an open back, crystal thong detailing, and a high ponytail topped with a black velvet Hailey Bieber Wears a Sheer Gucci Dress With a Visible Thong Mango featuring Hailey Bieber high neck backless ruffle maxi dress in brown ASOS Hailey Bieber Attends Met Gala in Sequin Thong Sans Justin Bieber BIN: Black Information Network Hailey Bieber flashes sideboob in second skin backless dress