css初级项目中导航栏下拉菜单实现

<nav class="navbar">
  <ul>
    <li><a href="#">首页</a></li>
    <li class="dropdown">
      <a href="#" class="dropbtn">服务</a>
      <ul class="dropdown-content">
        <li><a href="#">网页设计</a></li>
        <li><a href="#">前端开发</a></li>
        <li><a href="#">后端开发</a></li>
      </ul>
    </li>
    <li><a href="#">关于我们</a></li>
    <li><a href="#">联系</a></li>
  </ul>
</nav>

.navbar ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
  background-color: #333;
  overflow: hidden;
}

.navbar li a {
  display: block;
  color: white;
  text-align: center;
  padding: 14px 20px;
  text-decoration: none;
}

.navbar li a:hover {
  background-color: #555;
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #444;
  min-width: 160px;
  box-shadow: 0px 8px 16px rgba(0,0,0,0.2);
  z-index: 1;
}

.dropdown-content li a {
  padding: 12px 16px;
}

.dropdown:hover .dropdown-content {
  display: block;
}

.navbar ul {
  display: flex; /* 或者 float: left */
}

.dropdown {
  position: relative;
}