If the screenshots have uploaded correctly, they show that web pages are being cut-off slightly at the top when an external link is open in the In App Browser. The pages and header / toolbar within the app work fine. The problem is with the In App Browser and nothing I found to try to adjust the display once the IAB opens has worked. I have only seen this problem on my samsung s8 test device, android 7.0. Other android devices, Samsung S7 and Google Pixel, are fine.
and changing something on the viewport like initial scale=2.0 only affects the app/ built-in app pages. once it opens up the In App Browser window, the same problem persists.