Fix mermaid scaling for flowchart

layouts/shortcodes/mermaid.html

@@ -1,6 +1,11 @@
 {{ if not (.Page.Scratch.Get "mermaid") }}
 <!-- Include mermaid only first time -->
 <script src="{{ "mermaid.min.js" | relURL }}"></script>
+<script>
+mermaid.initialize({
+  flowchart: { useMaxWidth:true }
+});
+</script>
 {{ .Page.Scratch.Set "mermaid" true }}
 {{ end }}