<!DOCTYPE html>
<html>
<head>
<style>
div {
border: 1px solid black;
margin-bottom: 10px;
}
</style>
</head>
<body>
<div>
<h3>H3 element</h3>
<p>I am a p element, my parent is a div element.</p>
</div>
<div>
<h3>H3 element</h3>
<p>I am a p element, my parent is also a div element.</p>
</div>
<p>Click the button to change the background color of the first p element in the document where the parent is a div element.</p>
<button onclick="myFunction()">Try it</button>
<script>
function myFunction() {
var x = document.querySelector("div > p");
x.style.backgroundColor = "red";
}
</script>
</body>
</html>