Reset focus/zoom in mobile view on iPhone

#### Is your feature request related to a problem? Please describe

I came across a situation on an iPhone (not sure if it affects Android too) where after the user selects a text box to input information the viewport focuses on the text box and zooms in a bit. After leaving the field the same zoom is maintained. This causes dialogs which are rendered at the correct size for the original viewport size to appear clipped.

#### Describe the solution you'd like
The viewport should reset or the dialog should render proportional to the zoomed viewport.
(A clear and concise description of what you want to happen.)

#### Describe alternatives you've considered
I thought about setting a smaller size for the dialog but it would mean that the fixed size would be too small for desktop users.

Original render at correct size and dialog fits nicely

On tap, the text box is centred and the the viewport zooms in

When submitting the form any dialogs that are rendered appear clipped due to the screen retaining the zoom

No files, tests, or entry points are identified in the issue. Reproduce the iPhone text-field zoom and inspect the viewport and dialog behavior; done means dialogs remain fully visible after leaving a form field and submitting it.

Written by the indexing model from the issue text.