Disappearing Dropdown Menu

Hi there,

I edited my stylesheet for the Clean Retina theme to make the main menu smaller, as well as to make the space above the post title smaller.
However, in doing so I seem to have messed up my drop-down menus because when I hover over them the disappear before I can click. What part of the stylesheet do I need to adjust?
the site is http://www.jmeandjohn.com

Thanks for any help in advance!