Design updates to better match COSMIC

[jackpot51]

[jacobgkau]

This change makes the text a bit smaller, but it's still legible on both 1x and 2x scaled screens. It could be an accessibility concern.

lemp13 before/after:

addw2 before/after:

Open Sans does include ↑ and ↓ characters, so switching from that to the words Up and Down doesn't seem necessary. Despite Launch using the words, most keyboards include arrows. I don't think it's likely to result in any confusion, though.

I do want a sign-off from @system76/ux before we merge this. Better matching COSMIC means worse matching classic Pop!_OS, which is still what we currently ship as stable. (Not sure if this was intended to wait until closer to when COSMIC's ready.)