Primary nav hamburger icon and page title alignment incorrect, nav does not collapse

[stevepiercy]

The primary navigation hamburger icon and page title are stacked instead of aligned left to right.

That can be fixed with this style:

.header-article-items__start {
  align-items: start;
  display: flex;
}

However the sidebar does not collapse, but instead it jumps out when clicked.

This issue does not occur in Plone Sphinx Theme's demo or any other project that uses it, only in Training. We probably have some old CSS or JS that needs to be removed or updated. I'd prefer to remove customizations and have one fewer thing to maintain.

[stevepiercy]

Fixed by plone/documentation#1770