The message, or alert, box is a method of alerting a user to a success, a failure, or otherwise importantant contextual information that shlud stand-out due to it's importance. These would be event-propogated as part of a usage flow.
<div class="message-loading">
<span class="message">test message</span>
</div>
<div class="message-valid">
<span class="message">test message</span>
</div>
<div class="message-warning">
<span class="message">test message</span>
</div>