applets/kickoff: adjust visual density

This rebalances a few elements in Kickoff's UI, changing the perceived density without actually
substantially changing the region elements consume on-screen.

The changes in total are:
- smaller user real-name text; the jumbo text here crowds the text label against the top and bottom of the
  header, and often runs into the separator, giving the perception of a crowded design.
- a few extra pixels of vertical padding in the header and footer give the design more room to breathe, while
  only increasing the height of kickoff by less than 20 pixels on typical setups.