CSS CSS Transitions and Transforms Adding 3D Effects with CSS 3D Transforms Challenge

How can use 3D specific function

Am not understanding this question. I set the transform style and the rotation

style.css
/* Complete the challenge by writing CSS below */
.wrapper{
  perspective: 600px;
}
.photo{
  transform-style: 3d;
  transform: rotateX(30deg);
}
index.html
<!DOCTYPE html>
<html>
<head>
    <title>3D Transform Challenge</title>
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link href='https://fonts.googleapis.com/css?family=Open+Sans:400,300,600,700,800' rel='stylesheet' type='text/css'>
    <link rel="stylesheet" href="page.css">
    <link rel="stylesheet" href="style.css">
</head>
<body>

    <div class="wrapper">
        <img class="photo" src="1.jpg" alt="Dazzling Auroras">
    </div>

</body>
</html>