index.html

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <title>Slide In Infinite Scrolling</title>
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <link rel="stylesheet" href="style.css">
    </head>
    <body>
        <h1>Scroll down then up to see the animations!</h1>
        <div class="box"><h2>Content</h2></div>
        <div class="box"><h2>Content</h2></div>
        <div class="box"><h2>Content</h2></div>
        <div class="box"><h2>Content</h2></div>
        <div class="box"><h2>Content</h2></div>
        <div class="box"><h2>Content</h2></div>
        <div class="box"><h2>Content</h2></div>
        <div class="box"><h2>Content</h2></div>
        <script src="script.js" async defer></script>
    </body>
</html>