Weird theme issue when app is installed in real Smartphone.

So the problem started when I started making a dice roll app and tried to install in my phone(Vivo y55s). There was weird black background instead of white one(My question is here too but not answered https://stackoverflow.com/questions...ackground-when-app-is-installed-in-smartphone). I found that I was having the same problem when I created new 'Empty Activity' project(Android Lollipop 4.1 SDK) and simply install the apk in my phone after building it. So what could be the issue? The codes are default when we create an Empty Activity in AS and somehow I am getting full black screen and Hello World text in center(it works fine in emulator though).