R1:b4473d5998c6

Remove "min-width" from buttons

Summary:
This breaks Herald pretty badly too. We could restore it selectively; which buttons was it intended to affect?

{F26039}

Test Plan: Herald looks more reasonable now.

Reviewers: chad

Reviewed By: chad

CC: aran

Maniphest Tasks: T2090

Differential Revision: https://secure.phabricator.com/D4046