Bug 974867 - [MMS]Auto suggestion for email address r=Julien

https://bugzilla.mozilla.org/show_bug.cgi?id=974867
I sets  "1.5rem"  to the "padding-right" based on the follows. 
https://bug840515.bugzilla.mozilla.org/attachment.cgi?id=8399982
If I don't need setting, I'm going to modify as your indication.