Day min-height on mobile month calendar should be shorter.

Summary: Closes T8190, Day min-height on mobile month calendar should be shorter.

Test Plan: Mobile view of month view should fit on a mobile screen.

Reviewers: chad, #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T8190

Differential Revision: https://secure.phabricator.com/D12847