_includes/head.html

<head>
  <meta charset="utf-8" />
  <meta http-equiv="X-UA-Compatible" content="IE=edge" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />

  <!-- Google tag (gtag.js) -->
  <script
    async
    src="https://www.googletagmanager.com/gtag/js?id=G-JZ7VCSBD4M"
  ></script>
  <script>
    window.dataLayer = window.dataLayer || [];
    function gtag() {
      dataLayer.push(arguments);
    }
    gtag("js", new Date());

    gtag("config", "G-JZ7VCSBD4M");
  </script>

  <script type="text/x-mathjax-config">
    MathJax.Hub.Config({
      tex2jax: {
        inlineMath: [ ['$','$'], ["\\(","\\)"] ]
      }
    });
  </script>
  <script
    src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML"
    type="text/javascript"
  ></script>

  <!-- Code highlight -->
  <link rel="stylesheet" href="/assets/css/syntax.css" />

  <title>
    {%- if page.title -%} {{ page.title }} {%- else -%} {{ site.title }} {%-
    endif -%}
  </title>

  {%-seo title=false-%} {%-feed_meta-%}

  <link
    rel="shortcut icon"
    type="image/x-icon"
    href="{{ site.favicon | relative_url }}"
  />
  <link rel="stylesheet" href="{{ "/assets/css/main.css" | relative_url }}" />
</head>