<%= form_for(resource, as: resource_name, url: session_path(resource_name)) do |f| %>
  <div class="page-header">
    <h2><%= title 'Log in' %></h2>
  </div>

  <div class="row">
    <div class="form-group col-xs-4">
      <%= f.label :email %>
      <%= f.email_field :email, autofocus: true, class: %w(form-control t-email) %>
    </div>
  </div>

  <div class="row">
    <div class="form-group col-xs-4">
      <%= f.label :password %>
      <%= f.password_field :password, autocomplete: 'off', class: %w(form-control t-password) %>
    </div>
  </div>

  <% if devise_mapping.rememberable? -%>
    <div class="l-form-row">
      <%= f.check_box :remember_me, 't-remember-me' %>
      <%= f.label :remember_me %>
    </div>
  <% end -%>

  <p>
    <%= f.submit 'Log in', class: %w(t-submit) %>
  </p>
<% end %>

<%= render 'devise/shared/links' %>

<%= form_for(resource, as: resource_name, url: session_path(resource_name)) do |f| %>
  <div class="page-header">
    <h2><%= title 'Log in' %></h2>
  </div>

  <div class="row">
    <div class="form-group col-xs-4">
      <%= f.label :email %>
      <%= f.email_field :email, autofocus: true, class: %w(form-control t-email) %>
    </div>
  </div>

  <div class="row">
    <div class="form-group col-xs-4">
      <%= f.label :password %>
      <%= f.password_field :password, autocomplete: 'off', class: %w(form-control t-password) %>
    </div>
  </div>

  <% if devise_mapping.rememberable? -%>
    <div class="l-form-row">
      <%= f.check_box :remember_me, 't-remember-me' %>
      <%= f.label :remember_me %>
    </div>
  <% end -%>

  <p>
    <%= f.submit 'Log in', class: %w(btn btn-success t-submit) %>
  </p>
<% end %>

<%= render 'devise/shared/links' %>

Use Bootstrap style for login button
Use Bootstrap style for login button
