app/views/sessions/new.html.erb
<div class='container readable mt-5'>
<h1 class="text-center"><%= svg('infinitacle-round') %></h1>
<h3 class='text-center pt-3'>Sign into Octobox</h3>
<div class='text-center py-3'>
<%= form_tag('/auth/github', method: 'post') do %>
<button type='submit' class='btn btn-dark'>
<span class='mr-1'>Sign in</span>
<%= octicon 'mark-github', height: 22 %>
</button>
<% end %>
</div>
<%= render 'layouts/footer'%>
</div>