sub-menu doesn't show

Hi there,

I’m using the Semplice theme and have only quite poor css-knowledge, but I have managed to make the disabled submenu re-appear again with css – at least it shows up partly.

According to the visual overlay of my browser all the sub-menu items are there, but they don’t get displayed, as it seems they’re in conflict with the responsive menu!?

I’ve tried the z-index but to no avail and now I’m lost. I would greatly appreciate any help with this! Here’s the site I’m working on:

http://s363619762.online.de/

The submenu (vertical drowdown) sits under “units” and has six sub-nav items, but only one gets displayed, the others seem to be be hidden by the (hidden) responsive menu?!

Thank you very much everybody,
Marion