app/views/devise/sessions/new.html.erb
<div class="container">
<div class="row">
<div class="col-md-4 col-md-offset-4">
<div class="panel panel-default">
<div class="panel-heading">
<h2>Acceso</h2>
</div>
<div class="panel-body">
<p class="text-warning"><%= notice %></p>
<p class="text-danger"><%= alert %></p>
<%= simple_form_for(resource, as: resource_name, url: session_path(resource_name)) do |f| %>
<div class="form-inputs">
<%= f.input :email, required: false, autofocus: true %>
<%= f.input :password, required: false, label: 'ContraseƱa' %>
<%= f.input :remember_me, label: 'Mantenerme conectado', as: :boolean if devise_mapping.rememberable? %>
</div>
<div class="form-actions">
<%= f.button :submit, "Acceder" %>
</div>
<% end %>
<%= render "devise/shared/links" %>
</div>
</div>
</div>
</div>
</div>