<!DOCTYPE html>
<html>
<head>
<style>
.mystyle {
width: 300px;
height: 50px;
text-align: center;
background-color: coral;
color: white;
margin-bottom: 10px;
}
</style>
</head>
<body>
<p>In this example, we search for the first div element in the document. Then, if the div element has an id of "myDIV" - change its font size.</p>
<div id="myDIV" class="mystyle">
I am a DIV element
</div>
<button onclick="myFunction()">Try it</button>
<script>
function myFunction() {
var x = document.getElementsByTagName("DIV")[0];
if (x.id === "myDIV") {
x.style.fontSize = "30px";
}
}
</script>
</body>
</html>