Change font size of inputs to 1rem on mobile
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To reproduce:
1. On a mobile device or in a simulated iPhone in the Simulator app on macOS, tap a text field to focus it
2. When the text field focuses, the mobile browser will zoom in, because the font size of the input is < 16px/1rem
Recommended interventions:
1. We should use `font-size: 1rem;` for all `input`s and `textarea`s on mobile devices. This is a broad solution that is outside the scope of ~"group::product planning" and needs ~Pajamas team alignment
issue