Had the same problem. I think it is a background-image: linear-gradient(0deg,#b2b2b2,#b2b2b2 50%,transparent 50%); on the .bar class.
so try: .bar { background-image: none !important; }
Thanks so much, that was the issue for me as well. So weird only was showing the border on the phone in the app not in a browser or simulator’s browser. Wish I would have seen your answer about 30 minutes ago !!