Kirby CMS : Nested Menu http://getkirby.com/forum/code-snippets/topic:73

nested-menu.php

<ul>
  <?php foreach($pages->visible() AS $p): ?>
  <li>
    <a<?php echo ($p->isOpen()) ? ' class="active"' : '' ?> href="<?php echo $p->url() ?>"><?php echo html($p->title()) ?></a>
    
    <?php if($p->children()->visible()->count()): ?>
    <ul>
      <?php foreach($p->children()->visible() AS $item): ?>
      <li><a<?php echo ($item->isOpen()) ? ' class="active"' : '' ?> href="<?php echo $item->url() ?>"><?php echo html($item->title()) ?></a></li>
      <?php endforeach ?>            
    </ul>
    <?php endif ?>
  
  </li>
  <?php endforeach ?>
</ul>