Marking a message as read changes look & feel when > 2 messages

[hornd]

If you have more than 2 messages and you mark one as read, the message icon moves up and to the right and the color of the number changes.

That didn't make much sense, so:

Steps to reproduce:

Get 2 messages, mark one as read, and click away. Notice the "mail" icon has shifted and the color of the number of unread messages has changed.