在精确的中心位置实现粘性内容？

<div class="sticky-container">
  <div class="sticky-content">
    <!-- 粘性内容 -->
  </div>
</div>

.sticky-container {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.sticky-content {
  /* 粘性内容的样式 */
}

window.addEventListener('scroll', function() {
  var container = document.querySelector('.sticky-container');
  var content = document.querySelector('.sticky-content');
  var scrollTop = window.pageYOffset || document.documentElement.scrollTop;
  var containerTop = container.offsetTop;
  var containerHeight = container.offsetHeight;
  var windowHeight = window.innerHeight;

  if (scrollTop > containerTop && scrollTop < containerTop + containerHeight - windowHeight) {
    content.style.top = (windowHeight / 2) + 'px';
  } else if (scrollTop <= containerTop) {
    content.style.top = '';
  } else {
    content.style.top = (containerHeight - windowHeight / 2) + 'px';
  }
});