app/views/active_scaffold_overrides/_messages.html.erb
<% for name in [:info, :warning, :error] %>
<% if flash[name].present? %>
<div class="<%= "#{name}-message message" %>">
<%= display_message flash[name] %>
<% flash.delete name %>
<% if request.xhr? %>
<a href="#" class="close" title="<%= as_(:close) %>"><%= as_(:close) %></a>
<% end %>
</div>
<% end %>
<% end %>