web/_includes/mermaid.html

<!--
  mermaid-js loader
-->

<script src="https://cdn.jsdelivr.net/npm/mermaid@8/dist/mermaid.min.js"></script>
<script>
  $(function() {
    let initTheme = "default";

    if ($("html[mode=dark]").length > 0
      || ($("html[mode]").length == 0
        && window.matchMedia("(prefers-color-scheme: dark)").matches ) ) {
      initTheme = "dark";
    }

    let mermaidConf = {
      theme: initTheme  /* <default|dark|forest|neutral> */
    };

    /* Markdown converts to HTML */
    $("pre").has("code.language-mermaid").each(function() {
      let svgCode = $(this).children().html();
      $(this).addClass("unloaded");
      $(this).after(`<div class=\"mermaid\">${svgCode}</div>`);
    });

    mermaid.initialize(mermaidConf);
  });
</script>