dynamicProp.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <link rel="stylesheet" href="css/dynamicProp.css">
    <title>Document</title>
</head>
<body>
    
    <div class="card" style = "--x : 0; --y : 0;">
        <h1>Testing This</h1>
        <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Consequuntur enim itaque nisi. Ipsa deserunt maxime quae. Quasi qui molestias facere reiciendis, architecto vel assumenda suscipit magnam libero eius quo enim?</p>
    </div>


    <script>
    
        document.querySelector('.card').onmousemove = (e)=>{

            const x = e.pageX - e.target.offsetLeft;
            const y = e.pageY - e.target.offsetTop;

            e.target.style.setProperty('--x', `${x}px`)
            e.target.style.setProperty('--y', `${y}px`)
        }
    
    </script>
</body>
</html>