Make Phortune checkout UI a little less bad

Summary: Ref T2787. There were some mega-uggo buttons and such; reduce the uggo-ness by a hair.

Test Plan: {F179686}

Reviewers: btrahan, chad

Reviewed By: chad

Subscribers: epriestley

Maniphest Tasks: T2787

Differential Revision: https://secure.phabricator.com/D10006