如何实现这个粘性标题向下滚动组件？

<div class="sticky-header">
  <h1>粘性标题</h1>
</div>

.sticky-header {
  position: fixed;
  top: 0;
  width: 100%;
  background-color: #f1f1f1;
  padding: 10px;
  text-align: center;
  z-index: 9999;
}

window.addEventListener('scroll', function() {
  var header = document.querySelector('.sticky-header');
  var scrollPosition = window.scrollY;

  if (scrollPosition > 0) {
    header.classList.add('sticky');
  } else {
    header.classList.remove('sticky');
  }
});

.sticky-header.sticky {
  position: fixed;
  top: 0;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}