The only layout issue (related to paypal login) is the not user friendly login window because the login / cancel buttons are not visible and the user must scroll down to find they (see my attached screenshot).
Another example is the space to fill the "Enter email" filed is very limited (the user can't easily review the filled email).
So my question is: "How to set the PP login window to full screen (100%x and 100%y)" ?
Adaptive Payments is now a limited release product. It is restricted to select partners for approved use cases and should not be used for new integrations without guidance from PayPal.
Those building new integrations should consider using Braintree Payments, a PayPal Company, which is the easiest way to accept PayPal, credit cards, and many other payment methods.