app/views/sessions/new.html.erb
<%= form_tag(sessions_path, method: :post, class: "form-horizontal") do %>
<div class="form-group">
<h1 class="text-center">Sign in</h1>
<p class="alert-error"><%= flash[:notice] %></p>
<div class="col-sm-offset-5 col-sm-10" style="padding-top: 1%;">
<%= label_tag :email, nil, class: "col-sm-5 control-label" %>
<%= email_field_tag :email, '', autofocus: true %>
</div>
<div class="col-sm-offset-5 col-sm-10">
<%= label_tag :password, nil, class: "col-sm-5 control-label" %>
<%= password_field_tag :password %>
</div>
<div class="text-center">
<%= submit_tag "Sign in", class: "btn btn-primary btn-lg" %>
</div>
</div>
<% end %>