Try this fiddle
I would suggest adding some ID for selectors like below
JS $( document ).ready(function() {
$('#parent').hover(function() {
$('#submenu').stop(true, true).slideDown(200);
}, function() {
$('#submenu').stop(true, true).slideUp(200);
});
});
I am sure there is a more efficent way to do this but this is a good start.
EDIT
I think i found the actual issue with why it isn't sliding like you want it too, you have a style that is making it show instead of using the JS to make it show up
Remove this...
nav > div > ul > li:hover > ul {
display: block;
}
or try this fiddle http://jsfiddle.net/MzJNT/9/