<li>
     <!-- Pulling Categories from the database
     dynamically -->
     <?php $nav_subjects =
     find_all_subjects(['visible' =>
      $visible]);
                       while($nav_subject =
     mysqli_fetch_assoc($nav_subjects)) { ?>
                            <span c
     lass="opener"><?php echo
     h($nav_subject['menu_name']); ?></span>

<!-- Categories listed correctly let's pull the pages for each one -->
<?php if($nav_subject['id'] == $subject_id) {
    $nav_pages = find_pages_by_subject_id($nav_subject['id'], ['visible' => $visible]);
    while($nav_page = mysqli_fetch_assoc($nav_pages)) { ?>
    <ul>
    <li>
    <a href="<?php echo url_for('index.php?id=' . h(u($nav_page['id']))); ?>"><?php echo h($nav_page['menu_name']); ?></a>
    </li>
    </ul>
    <?php } // while $nav_pages
    } // if($nav_subject['id'] == $subject_id)
  } // while $nav_subjects ?>
    </li>
    <?php mysqli_free_result($nav_subjects);
    mysqli_free_result($nav_pages); ?>