UX: more consistent mobile spacing (PR #13297)

Spacing between the header and content was very tight in some places, and generally not consistent. This increases the space a little and makes it more consistent.

Before:

Screen Shot 2021-06-04 at 6 13 00 PM Screen Shot 2021-06-04 at 6 13 31 PM Screen Shot 2021-06-04 at 6 13 23 PM Screen Shot 2021-06-04 at 6 13 06 PM

After:

Screen Shot 2021-06-04 at 6 10 32 PM Screen Shot 2021-06-04 at 6 01 06 PM Screen Shot 2021-06-04 at 6 00 58 PM Screen Shot 2021-06-04 at 6 00 49 PM

GitHub