Mermaid Update

Adds the CDN replacement for Mermaid and adds CSS to constrain them to their parent DIVs.

_layouts/assignment.html

@@ -66,7 +66,7 @@
       {% include footer.html %}
     </main>
 
-  <script src="{{ '/assets/js/mermaid.js' | relative_url}}"></script>
+  <script src="https://cdn.jsdelivr.net/npm/mermaid/dist/mermaid.min.js"></script>
   <link rel="stylesheet" href="{{ '/assets/css/mermaid.css' | relative_url }}">
   <link rel="stylesheet" href="{{ '/assets/css/assignment.css' | relative_url }}">
   <script>mermaid.initialize({startOnLoad:true});</script>