css二级导航菜单代码

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>CSS 二级导航菜单</title>
<style>
  body {
    font-family: Arial, sans-serif;
  }
  .nav {
    list-style-type: none;
    margin: 0;
    padding: 0;
    background-color: #333;
    overflow: hidden;
  }
  .nav li {
    float: left;
  }
  .nav li a, .dropdown-btn {
    display: inline-block;
    color: white;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
  }
  .nav li a:hover, .dropdown:hover .dropdown-btn {
    background-color: red;
  }
  .dropdown-content {
    display: none;
    position: absolute;
    background-color: #f9f9f9;
    min-width: 160px;
    box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
    z-index: 1;
  }
  .dropdown-content a {
    color: black;
    padding: 12px 16px;
    text-decoration: none;
    display: block;
    text-align: left;
  }
  .dropdown-content a:hover {background-color: #f1f1f1}
  .dropdown:hover .dropdown-content {
    display: block;
  }
</style>
</head>
<body>

<ul class="nav">
  <li><a href="#home">首页</a></li>
  <li class="dropdown">
    <a href="javascript:void(0)" class="dropdown-btn">产品</a>
    <div class="dropdown-content">
      <a href="#">产品1</a>
      <a href="#">产品2</a>
      <a href="#">产品3</a>
    </div>
  </li>
  <li><a href="#contact">联系我们</a></li>
</ul>

</body>
</html>