For a large portion of the second half of the movie, Baroness Teri von Horhenfels (Kay Francis) wears a gown which is backless, off the shoulders, and has a low front neckline. There are no visible means of support, yet the gown stays firmly in place. One possible answer is that the tops of the sleeves are tightly held to her upper arms, perhaps with elastic, and this is the support for the gown as a whole.
