app/views/layouts/_flash.html.erb
<% unless flash.empty? %>
<div id="flash-messages">
<% flash.each do |key, value| %>
<% if value.is_a?(String) %>
<div class="<%= flash_class(key) %> alert-dismissible">
<div class="container">
<span class="<%= flash_icon_class(key) %>"></span>
<%= value %>
<button type="button" class="close-button" data-dismiss="alert" data-target=".alert-dismissible">
<span class="geomicon geomicon-delete"></span>
</button>
</div>
</div>
<% end %>
<% end %>
</div>
<% end %>