Painfully dumb question

I’m certain that this has been addressed here somewhere in the threads, but various searches proved fruitless. I am building a pretty basic javascript-css menu interface (I want to call it “drop-down” but that may be incorrect) where divs containing submenus appear and disappear below header menu items as the user mouses on and off of them (the headers). That seems to be working fine enough. My issue deals with getting the divs to disappear when they are moused out of. Unfortunately the onmouseout call I am using to make the submenu divs disappear is being triggered when I mouse over elements inside the divs, such as the table containing the submenu options. How do I work around this?

Thanks again in advance for your patience and time with my ignorance on what should be a rather simple matter.