I looked at your site, but I’m struggling a little to understand what you want the drop-down div to do. Can you do a rough drawing or point us at a site that does something similar to what you need?
Ah! OK, I’d not recognized that as having any particular association with the menu. Hopefully someone will chip in with some ideas, I’m not best placed to respond where I am at the moment.
You have css comments in the html which is not allowed.
This is a css comment:
/* this is a css comment and only goes in css files */
This is an html comment:
<!-- this is an html comment and only goes in html files -->
Note that you are toggling the .ieventimage div when you click the list item (or when clicking anything inside including the newly displayed div) which means that it will also close when you click it again. If that’s what you wanted then that’s fine.