Form items should be wider on narrow screen sizes

I've noticed that the form items are quite small on mobile device.

In Seven we increased the width on narrow devices:
#1751150: Improve usability of forms on touch screen and small screen devices

I think we should do the same here, it's a nice usability win for touch devices.

Remaining tasks

Write a patch that changes all form items similar to #1751150: Improve usability of forms on touch screen and small screen devices
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