Some frameworks generate error flash messages with error
modifier. This makes them look just like original
Bootstrap’s .alert-danger
.
Example
What a mistake!
<div class="alert alert-error alert-dismissible fade in">
<button type="button" class="close" data-dismiss="alert">×</button>
<span class="glyphicon glyphicon-warning-sign offset-right" aria-hidden="true"></span>
What a mistake!
</div>