mermaidjs.html

<script src="https://cdn.jsdelivr.net/npm/mermaid/dist/mermaid.min.js"></script>
<script>
mermaid.initialize({startOnLoad:true});
</script>
<style>
    .mermaid {  /* add custom styling */  }
</style>


<!--This will render scripts when the document loads once. 

If you dynamically change the document in JavaScript that affects the Mermaid code (like page navigation in SPA apps), you might need to update and re-render the diagrams. The code below is from Markdown Monster which uses an event to trigger a re-render when the Previewer content is refreshed (without a full page reload):
-->

<script src="https://cdn.jsdelivr.net/npm/mermaid/dist/mermaid.min.js"></script>
<script>
mermaid.initialize({startOnLoad:false});
</script>
<script>
function renderMermaid(){
    mermaid.init(undefined,document.querySelectorAll(".mermaid"));
}
$(function() {
    $(document).on('previewUpdated', function() {        
        renderMermaid();
    });
    renderMermaid();
});
</script>