Tweak some minor UI elements in garden-o-matic

This CL cleans up a few minor UI nits in Garden-O-Matic.

R=dpranke@chromium.org, dpranke

Review URL: https://codereview.chromium.org/23629045

git-svn-id: svn://svn.chromium.org/blink/trunk@157767 bbb929c8-8fbe-4397-9dbb-9b2b20218538