Scrolling
As the body of the page is set up now, pages are not scrollable. A quick example of the problem is in scienceblogger. Just try to add enough blogposts until you exceed the height of the page. You then have no way to access the last ones (or the add button) unless you delete some.
We have the same problem in book builder and I guess that this will be a problem with any component that can grow in height. We temporarily added a scrollbar to the html body, but that breaks the editor, as it tries to get the full height of the remaining page. (you can see this if you try to scroll in the editor version that is up on editoria)
Was your initial intention to have a fixed navigation bar and have the rest of the page be scrollable?
Or did you want the whole page to scroll?
In any case, we'd be happy to PR the fix.