Mobile Collapsing Nested Menu

collapsing-mobile-nav.css

.et_mobile_menu .first-level > a {
  background-color: transparent;
  position: relative;
}

.et_mobile_menu .first-level > a:after {
  font-family: 'ETmodules';
  content: '\4c';
  font-weight: normal;
  position: absolute;
  font-size: 16px;
  top: 13px;
  right: 10px;
}

.et_mobile_menu .first-level > .icon-switch:after {
  content: '\4d';
}

.second-level {
  display: none;
}

.reveal-items {
  display: block;
}

.et_mobile_menu {
  margin-top: 20px;
  width: 230%;
  margin-left: -65%;
}

collapsing-mobile-nav.js

// https://www.elegantthemes.com/blog/divi-resources/how-to-create-a-mobile-collapsing-nested-menu-with-divis-theme-builder

(function ($) {
  function setup_collapsible_submenus() {
    var FirstLevel = $('.et_mobile_menu .first-level > a');

    FirstLevel.off('click').click(function () {
      $(this).attr('href', '#');
      $(this).parent().children().children().toggleClass('reveal-items');
      $(this).toggleClass('icon-switch');
    });
  }

  $(window).load(function () {
    setTimeout(function () {
      setup_collapsible_submenus();
    }, 700);
  });
})(jQuery);