Vertical menu with subitems also vertically

Hi all,

I like to have a vertical menu with clicking on a menu item, the subitem should be displayed also vertically.

Item 1
Item 2

You click on Item 2 :

Item 1
Item 2
Subitem 1
Subitem 2

Example : http://www.salon-nouveau.nl/schoonheidssalon.html

Anyone can help me to setup this?

Thanks.