CSS - position: sticky

HTML

<!DOCTYPE html>
<html>
<head>
    <link rel="stylesheet" href="web.css">
    <meta charset="utf-8" />
    <title>Homework</title>
</head>
<body>
    <img id="logo" src="https://scontent.ftlv2-1.fna.fbcdn.net/v/t1.0-9/37245582_293862567854271_787677898071867392_n.png?_nc_cat=105&_nc_ht=scontent.ftlv2-1.fna&oh=9f5cc2759559a40e089ff7c1ffa28952&oe=5CAF0323" alt="gocode" width=" 150px;">
    
        <ul>
        <li><a href="">Home</a></li>
        <li><a href="">Menu</a></li>
        <li><a href="">servies</a></li>
        <li><a href="">About</a></li>
        <li><a href="">Contact</a></li>
        <li><a href="">News</a></li>
        <li><a href="">Faq</a></li>


      </ul>

      <h1 class="mid">ARE YOU READY ?</h1>

      <a href="">
            <div id="mid1">Watch video </div>
          </a>
          
    <a href="">
      <div id="mid">Explore More </div>
    </a>

    <a href="">
        <div id="bottom-right">subscribe</div>
    </a>

</body>
</html>

CSS

body{
    background-image: url(http://4.bp.blogspot.com/-yiDcScBd14I/VisvsvsrkyI/AAAAAAAAAX8/li92jLVzYTw/s1600/5su8sTX.jpg);
}

#logo{
    position: absolute;
    left: 60px;
    top: 20px;
}
ul {
    font-weight: bold;
    float: right;
    text-align: center;
    
}

li {
    font-weight: bold;
    text-align: center;
    padding: 0px 10px;
    color: white;
    float: left;
    list-style-type: none;
}

a:hover{
    width: 2000px;
    height: 2000px;
    border: 2px solid white;
}
:link, :active, :visited{
    color: white;
    padding: 5px;
}
.mid{
    font-weight: bold;
    color: white;
    position: absolute;
    left: 0;
    top: 50%;
    width: 100%;
    text-align: center;
}
#mid{
    position: absolute;
    left: 52%;
    top: 60%;
    text-align: center;
    border: 1px solid black;
    padding: 5px;
}
#mid1{
    background-color: orange;
    position: absolute;
    left: 42%;
    top: 60%;
    text-align: center;
    border: 1px solid black;
    padding: 5px;
}
#bottom-right{
    font-weight: bold;
    color: red;
    position: absolute;
    bottom: 8px;
    right: 16px;
    font-size: 18px;    
    border: 2px solid black;
    padding: 0px 0px 0px 30px;
    
}