My tests on iPhone 7, iPad Pro, Android v8 w/Chrome were just fine.
I scrolled down to click into the last field.
A keyboard popped up, and the screen scrolled up.
After typing text, when the keyboard closed, the screen scrolled back down and seemed to be normal operation.
In the past, I HAD seen this odd behavior where the screen did NOT re-adjust after closing keyboard - but I tend to think it was with my "native" mobile app (which I can't rebuild because I haven't adjusted to the non-PGB method yet.)
And for some reason, I have this line in my startup.html from some prior fiddling:
<meta name="viewport" content="width=device-width, initial-scale=1">