On a very small resolution (below 16.5em) when navigation toolbar collapses to one row with icons and labels - it's impossible to go through some top menu items.
To reproduce: click on 'Manage' menu item so that it is expanded. Then you can see parent toolbar menu items overlap inner 'Manage' elements. And actually all overlapped elements are not clickable so you can't go to e.g. 'Content'.
In the image "Navigation menu - overlapped.png" with red rectangle you can see overlapped elements that are not clickable.