如何通过纯CSS实现网页的平滑滚动导航菜单

<nav class="smooth-scroll-nav">
  <ul class="smooth-scroll-menu">
    <li><a href="#section1">Section 1</a></li>
    <li><a href="#section2">Section 2</a></li>
    <li><a href="#section3">Section 3</a></li>
    <li><a href="#section4">Section 4</a></li>
  </ul>
</nav>

<section id="section1">
  <h2>Section 1</h2>
  <p>This is the content of section 1.</p>
</section>

<section id="section2">
  <h2>Section 2</h2>
  <p>This is the content of section 2.</p>
</section>

<section id="section3">
  <h2>Section 3</h2>
  <p>This is the content of section 3.</p>
</section>

<section id="section4">
  <h2>Section 4</h2>
  <p>This is the content of section 4.</p>
</section>

.smooth-scroll-nav {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  background-color: #333;
  padding: 10px 0;
}

.smooth-scroll-menu {
  list-style: none;
  margin: 0;
  padding: 0;
  text-align: center;
}

.smooth-scroll-menu li {
  display: inline-block;
  margin-right: 15px;
}

.smooth-scroll-menu li:last-child {
  margin-right: 0;
}

.smooth-scroll-menu a {
  color: #fff;
  text-decoration: none;
  padding: 5px 10px;
}

.smooth-scroll-menu a:hover {
  background-color: #fff;
  color: #333;
}

html {
  scroll-behavior: smooth;
}

@media screen and (-webkit-min-device-pixel-ratio:0) {
  /* 回退方案：使用jQuery滚动动画 */
  .smooth-scroll-nav a {
    transition: all 0.3s ease-in-out;
  }
  
  .smooth-scroll-nav a[href^="#"] {
    position: relative;
  }
  
  .smooth-scroll-nav a[href^="#"]:after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 0;
    height: 2px;
    background-color: #fff;
    transition: all 0.3s ease-in-out;
    transform: translateX(-50%);
  }
  
  .smooth-scroll-nav a[href^="#"]:hover:after,
  .smooth-scroll-nav a[href^="#"]:focus:after {
    width: 100%;
  }
}

$(function() {
  $('a[href^="#"]').on('click', function(e) {
    e.preventDefault();
    var target = $(this.getAttribute('href'));
    if (target.length) {
      $('html, body').stop().animate({
        scrollTop: target.offset().top
      }, 1000);
    }
  });
});