Problem with submenu position when nav bar is at the bottom

The easiest way would be to react to the change of classes assigned to the main menu bar – when it docks top – there’s added class .site-navigation-fixed. Making it work fully is not so quick and easy process, especially when you do the edits in the Chrome developer tools 🙂 You have to take care of the RWD version too.

I made some changes for you for a start:

@media screen and (min-width: 48em) {
   .navigation-top.site-navigation-fixed ul li:hover > ul,
   .navigation-top.site-navigation-fixed ul li.focus > ul {
       top: 100px;
   }
}

@media screen and (min-width: 48em) {
   .main-navigation ul li:hover > ul, .main-navigation ul li.focus > ul {
       left: -6.5em;
       right: auto;
       top: -100px;
   }
}