[DO NOT MERGE]  Styles for search filter in homepage

Supercedes https://github.com/mozilla/kuma/pull/2149

This *should* be an accurate cleanup of @tx2z's original PR.  I've updated the author to give him full credit.

One outstanding issue here is that I'm getting a Python error when doing a search from the homepage:

https://gist.github.com/darkwing/c7ed71ffc46799b28228