Rails flash partial with Bootstrap classes

_flash.html.erb

<% unless flash.empty? %>

  <% flash.each do |key, value| %>
    <div class="main-flash alert alert-<%= flash_css_class(key) %> text-center" style="border-radius: 0;">
      <%= value %>
    </div>
  <% end %>

<% end %>

application_helper.rb

module ApplicationHelper
  def flash_css_class(key)
    if ['notice', 'error'].include?(key)
      key == 'notice' ? 'info' : 'danger'
    else
      key.to_s
    end
  end
end