app/views/devise/invitations/edit.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">
<p>Welcome to the <strong><%= Setting.site_title %></strong>! Please set a password for your account before continuing.</p>
<h2>Set your password</h2>
<%= form_for resource, :as => resource_name, :url => invitation_path(resource_name), :html => {:method => :put} do |f| %>
<div class="form-group">
<%= devise_error_messages! %>
<%= f.hidden_field :invitation_token %>
</div>
<div class="form-group">
<%= f.label :password %>
<%= f.password_field :password, :class => 'form-control', :autofocus => true %>
</div>
<div class="form-group">
<%= f.label :password_confirmation, 'Confirm new password' %>
<%= f.password_field :password_confirmation, :class => 'form-control' %>
</div>
<div class="form-group">
<%= f.submit t("devise.invitations.edit.submit_button"), :class => "btn btn-primary btn-block" %>
</div>
<% end %>
</div>
</div>
</div>