Fix "similar-code" issue in src/utils/interface.js

Similar blocks of code found in 3 locations. Consider refactoring.

https://codeclimate.com/github/jwu910/check-it-out/src/utils/interface.js#issue_5c61a96c7c4f6f0001000030

If we can isolate similar "theme" styles for our interface objects, lets move that code into another variable to keep the code DRY.