app/views/shopping_cart/login_or_register.html.erb
<%= render 'checkout_steps' %>
<div class="container">
<div class="col-sm-12 col-md-10 col-md-offset-1">
<h1 class="page-header">Please log in or register</h1>
<div class="panel with-nav-tabs panel-default">
<div class="panel-heading">
<ul class="nav nav-tabs">
<li class="active"><a href="#tab1default" data-toggle="tab"><strong>Register</strong></a></li>
<li><a href="#tab2default" data-toggle="tab">Already have an account? <strong>Sign in</strong></a></li>
</ul>
</div>
<div class="panel-body">
<div class="tab-content">
<div class="tab-pane fade in active" id="tab1default">
<%= render partial: 'customer/customers/form', locals: {redirect: "checkout"} %>
</div>
<div class="tab-pane fade" id="tab2default">
<%= render partial: 'customer/sessions/login_form', locals: {redirect: "checkout"} %>
</div>
</div>
</div>
</div>
</div>
</div>