ipt>
  <script src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script>
  <script type="text/javascript" id="MathJax-script" async
    src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js">
  </script>
{% endif %}

<!-- commons -->

<script src="https://cdn.jsdelivr.net/combine/npm/popper.js@1.16.1,npm/bootstrap@4/dist/js/bootstrap.min.js"></script>

{% if jekyll.environment == 'production' %}
  <!-- PWA -->
  <script defer src="{{ '/app.js' | relative_url }}"></script>

  <!-- GA -->
  {