<!DOCTYPE html>
<html>
<head>
<style>
input[type=text] {
width: 100%;
padding: 12px 20px;
margin: 8px 0;
box-sizing: border-box;
border: 1px solid #555;
outline: none;
}
input[type=text]:focus {
background-color: lightblue;
}
</style>
</head>
<body>
<p>In this example, we use the :focus selector to add a background color to the text field when it gets focused (clicked on):</p>
<form>
<label for="fname">First Name</label>
<input type="text" id="fname" name="fname" value="John">
<label for="fname">Last Name</label>
<input type="text" id="lname" name="lname" value="Doe">
</form>
</body>
</html>