app/views/shared/_alerts.html.erb
<% unless flash.empty? %>
<div class="alerts">
<% flash.each do |name, msg| %>
<div class="alert alert-<%= name %>" data-components="alert" role="alert">
<a class="close" aria-label="t('js.modal.close')">×</a>
<%= raw msg %>
</div>
<% end %>
</div>
<% end %>