bootstrap button danger , notice code example
Example 1: bootstrap flash message
<div class="alert alert-success alert-dismissible fade show" role="alert">
<strong>Holy guacamole!</strong> You should check in on some of those fields below.
<button type="button" class="close" data-dismiss="alert" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
Example 2: alert bootstrap
<div class="alert alert-warning alert-dismissible fade show" role="alert">
<strong>Holy guacamole!</strong> You should check in on some of those fields below.
<button type="button" class="close" data-dismiss="alert" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>