app/views/devise/invitations/new.html.erb
<div class="container">
<div class="row">
<div class="col-sm-6 col-sm-offset-3 col-xs-8 col-xs-offset-2 form-frame">
<h2><%= t "devise.invitations.new.header" %></h2>
<%= form_for resource, :as => resource_name, :url => invitation_path(resource_name), :html => {:method => :post} do |f| %>
<div class="form-group">
<%= devise_error_messages! %>
</div>
<% resource.class.invite_key_fields.each do |field| -%>
<div class="form-group">
<%= f.label field %>
<%= f.text_field field, :class => 'form-control' %>
</div>
<% end -%>
<div class="form-group">
<%= f.submit t("devise.invitations.new.submit_button"), :class => 'btn btn-primary btn-block' %>
</div>
<% end %>
</div>
</div>
</div>