{% if site.github_username != null %}
<a href="https://github.com/{{site.github_username}}" target="_blank">
  <i class="fa fa-github fa-3x"></i>
</a>
{% endif %}
{% if site.email != null %}
<a href="mailto:{{site.email}}">
  <i class="fa fa-envelope fa-3x"></i>
</a>
{% endif %}