Dropdown menus partially hidden behind second row of main menu (IE8, Chrome, & FF)

I am using the Marinelli theme in Drupal 7, and have 2 horizontal rows that make up my main menu. While having the dropdown menus turned on for the main menu, the dropdown menus are partially hidden behind the 2nd row of the main menu, and content from the content area is showing through the menu. This happens in IE8, Chrome, and FF. This also happens if I use the Superfish module, but for now I'm trying to find a fix within the Marinelli theme. I've tried a few z-index changes in various css files, but nothing so far has worked (or I haven't found the correct file and code to fix it). Initially I had posted this issue in the Zero Point theme area, but since have started with the Marinelli theme and see the same issue happening. Sorry, but I'm not sure how to post this issue at a higher level outside of a specific theme, if it should be. Please help.