Add a blank overlay div to the DOM for clicking. http://www.calvinkoepke.com/add-a-mobile-friendly-off-canvas-menu-in-genesis/

functions.php

<?php
//* Do NOT include the opening PHP tag

/** 
  * Add the overlay div that will be used for clicking out of the active menu.
  * @author Calvin Koepke (@cjkoepke)
  * @link http://www.calvinkoepke.com/add-a-mobile-friendly-off-canvas-menu-in-genesis
*/
add_action( 'genesis_before', 'ck_site_overlay', 2 );
function ck_site_overlay() {
  
  echo '<div class="site-overlay"></div>';

}