Bug 870612 - [MMS] Composer. "TO" field has a wrong shape between itself and the header - r=borjasalguero

This restores the correct CSS styles lost in the merge on Wednesday night.

https://bugzilla.mozilla.org/show_bug.cgi?id=870612

Closes bocoup/gaia#6

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>