Use jQuery to hide a DIV when the user clicks outside of it

 $(document).mouseup(function(e) 

{
    var container = $("YOUR CONTAINER SELECTOR");

    // if the target of the click isn't the container nor a descendant of the container
    if (!container.is(e.target) && container.has(e.target).length === 0) 
    {
        container.hide();
    }
});