如何在Jekyll网站上实现可折叠菜单

<ul class="menu">
  <li>
    <a href="#">菜单项1</a>
    <ul class="submenu">
      <li><a href="#">子菜单项1</a></li>
      <li><a href="#">子菜单项2</a></li>
    </ul>
  </li>
  <li>
    <a href="#">菜单项2</a>
    <ul class="submenu">
      <li><a href="#">子菜单项3</a></li>
      <li><a href="#">子菜单项4</a></li>
    </ul>
  </li>
</ul>

.menu {
  list-style: none;
  padding: 0;
}

.menu li {
  position: relative;
}

.menu li a {
  display: block;
  padding: 10px;
  background-color: #f0f0f0;
  color: #333;
  text-decoration: none;
}

.menu li:hover > .submenu {
  display: block;
}

.submenu {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  padding: 0;
  background-color: #f0f0f0;
}

.submenu li {
  width: 200px;
}

.submenu li a {
  padding: 10px;
  color: #333;
  text-decoration: none;
}

.submenu li:hover {
  background-color: #ccc;
}

var menuItems = document.querySelectorAll('.menu li');

menuItems.forEach(function(item) {
  var submenu = item.querySelector('.submenu');
  if (submenu) {
    item.addEventListener('click', function() {
      submenu.style.display = (submenu.style.display === 'block') ? 'none' : 'block';
    });
  }
});