Background fixed with sticky header

<!DOCTYPE html>
<html>
<head>
<title></title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width">
<style>

img{opacity:0.5;position:fixed;width:50%;height:500px;
                  top:100px;left:25%;}
h1{font-size:50px; text-align:center;position:sticky;top:0;margin-top:0;}
h2{font-size:30px;}
li{font-size:30px;}
</style>
</head>
<body>

<h1>HTML [ BASIC ]</h1>

<img src='https://cdn.pixabay.com/photo/2017/08/05/11/16/logo-2582748_960_720.png'/>
<ol>
<h2>TABLE OF CONTENT </h2>
<li>Startup</li>
<li>Basic Tags</li>
<li>Style & Color</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
<li>..............................</li>
</ol>


<script>

</script>
</body>
</html>