marp-mermaid-example.html

<script src="https://cdn.jsdelivr.net/npm/mermaid@10/dist/mermaid.min.js"></script>
<script>
  mermaid.initialize({ startOnLoad: false });

  document.addEventListener("DOMContentLoaded", () => {
    document.querySelectorAll('code.language-mermaid').forEach((codeBlock, index) => {
      const parent = codeBlock.parentElement;
      const container = document.createElement('div');
      container.className = 'mermaid';
      container.innerHTML = codeBlock.textContent;

      parent.replaceWith(container);
    });

    mermaid.init(undefined, document.querySelectorAll('.mermaid'));
  });
</script>