Tryit Editor v2.9

Edit This Code:
<!DOCTYPE html>
<html>
<head>
<style>
h1:before {
    counter-increment: section;
    content: "Section " counter(section) ". ";
}
</style>
</head>
<body>

<p>Click the "Try it" button to set the counter-reset property of the BODY element:</p>

<button onclick="myFunction()">Try it</button>

<h1>HTML Tutorials</h1>
<h1>JavaScript Tutorials</h1>
<h1>CSS Tutorials</h1>

<script>
function myFunction() {
    document.body.style.counterReset = "section";
}
</script>

</body>
</html>