How can I style the back of a 3d object when it rotates?

Question

I am trying to give a different style to the back of the iphone 7 in my code when it rotates.

https://code.sololearn.com/W2jsG4apmkN1/?ref=app

Answer 1

It's still the same! I don't want the MINIMIZE button to be visible when it has rotated, facing the back(i.e. 180°).

Answer 2

//Give a background color to ffront and screen class

//Here is a example
https://code.sololearn.com/WjgGeSVAJ3en/?ref=app