Tryit Editor v2.9

Edit This Code:
<!DOCTYPE html>
<html>
<head>
<style>
#myDIV {
    border: 1px solid black;
}
</style>
</head>
<body>

<div id="myDIV">
  <h2>A h2 element in div</h2>
  <h3>A h3 element in div</h3>
</div>

<script>
var x = document.getElementById("myDIV");
x.querySelector("h2, h3").style.backgroundColor = "red";
</script>

</body>
</html>