<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <style>
       /* 填写样式 */
    </style>
</head>

<body>
   <header>
        <nav></nav>
   </header>
    <script type="text/javascript">
        /* 填写JavaScript */
        
    </script>
</body>

</html>