Click any where that isn't the nav to close but clicking anywhere on the nav won't close it. The one is also staggered closing multiple nav levels.

Outside the nav click.js

/**
* Closes all navigation layers, staggered from bottom
* if the user clicks anywhere outside of the nav
*/
$('html').on('click', function(event) {
    // if the closest parent is not the nav
    if (!$(event.target).closest('nav').length) {
        // get all elements with the nav--open class and reverse the array
        $($('.nav--open').get().reverse()).each(function(i, el) {
            // remove the element nav--open class with 300ms * i delay to get the stagger effect
            (function(i){
                setTimeout(function(){
                    $(el).removeClass('nav--open');
                }, 300 * i);
            }(i));
        });
    }
});