fix script loading

layouts/shortcodes/mermaid.html

@@ -1,10 +1,12 @@
 {{ if not (.Page.Scratch.Get "mermaid") }}
 <!-- Include mermaid only first time -->
 <script defer src="{{ "js/mermaid.min.js" | relURL }}"></script>
-<script defer>
-  mermaid.initialize({
-    flowchart: { useMaxWidth: true }
-  });
+<script>
+    document.addEventListener("DOMContentLoaded", function(event) {
+        mermaid.initialize({
+            flowchart: { useMaxWidth: true }
+        });
+    });
 </script>
 {{ .Page.Scratch.Set "mermaid" true }}
 {{ end }}