<!DOCTYPE html>
<html>
<head>
<title>Title of the Document</title>
<style>
#divId {
color: green;
font-size: 25px;
}
span {
color: blue;
font-size: 20px;
}
</style>
</head>
<body>
<div id="divId">Welcome to W3docs</div>
<script>
function insertAfter(referenceNode, newNode) {
referenceNode.parentNode.insertBefore(newNode, referenceNode.nextSibling);
}
let elem = document.createElement("span");
elem.innerHTML = "It's a Javascript book";
let div = document.getElementById("divId");
insertAfter(div, elem);
</script>
</body>
</html>