You might have some trouble with the presentation sections as they are a bit fiddly to navigate and, as the content loads from another small website, it can take a few seconds if your connection is slow or you are outside Europe  (you just see a blank area). You could try f5 / refresh to encourage it if it fails to load in 10 seconds or so. Should be faster next time once it loads.

Always use the link to open the content in a new tab if you can't see things easily.