如何在移动设备上隐藏php中的div内容？

@media only screen and (max-width: 768px) {
  .hidden-div {
    display: none;
  }
}

if (/Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent)) {
  document.getElementById("div-id").style.display = "none";
}

<?php
$isMobile = false;
$userAgent = $_SERVER['HTTP_USER_AGENT'];
$mobileKeywords = array('Android', 'webOS', 'iPhone', 'iPad', 'iPod', 'BlackBerry', 'IEMobile', 'Opera Mini');
foreach ($mobileKeywords as $keyword) {
  if (strpos($userAgent, $keyword) !== false) {
    $isMobile = true;
    break;
  }
}

if (!$isMobile) {
  echo '<div>Content to be hidden on mobile devices</div>';
}
?>