Display Access granted message with correct credentials using PHP

<!DOCTYPE html>
<html>
<body>
<h1>Login</h1>
<form method="POST">
Username:
<input type="text" id="username" name="username"><br>
Password:
<input type="password" id="password" name="password"><br>
<input type="submit" value="Login">
</form>
<?php
	$username = "prajwal";
	$password = "password";
	if (isset($_POST["username"]) && isset($_POST["password"])) 
	{
	if ($_POST["username"] == $username && $_POST["password"] == $password) 
	{
		echo "<p>Access Granted, " . $username . "!</p>";
	} 
		else 
		{
		echo "<p>Invalid username or password.</p>";
		}
	}
	?>
</body>
</html>