cycat-project-website/_includes/google-analytics.html

{% if site.google_analytics_id %}
  <!-- Global site tag (gtag.js) - Google Analytics -->
  <script async src="https://www.googletagmanager.com/gtag/js?id={{ site.google_analytics_id }}"></script>
  <script>
    window.dataLayer = window.dataLayer || [];
    function gtag(){dataLayer.push(arguments);}
    gtag('js', new Date());
  
    gtag('config', '{{ site.google_analytics_id }}');
  </script>
{% endif %}