- It can be confusing what the main and what the sub menu is.
- The header of the sub menu on the left should be shown in order to make clear that the
right menu is a sub menu of the left main menu.
- If I am below the area where the sub menu is shown, I am not able to navigate
within a main point. I have to scroll up until the left sub menu is shown.
=> Replace the navigation by a single tree navigation on the left whose elements can be collapsed and expanded
or use nested pages where always only one navigation is shown.