Previously we had an iOS-specific sizing rule which would increase inputs to `1.07em`, which would bring them over the 16px 'zoom on focus' threshold in some (but technically, not all) situations.
This commit does two things:
1. Updates the sizing rule from `1.07em` to `max(1em, 16px)`. Essentially: use the cascaded font size, unless it is smaller than 16px
2. Applies that sizing rule on all platforms. This will make Discourse design/theming more consistent across different devices
It also removes some associated CSS rules which no longer make sense.
d0d4a363d4