<!Doctype html>
<html>
<style>
#container {
width: 400px;
height: 400px;
position: relative;
background: yellow;
}
#animate {
width: 50px;
height: 50px;
position: absolute;
background: red;
}
</style>
<body>
<h1>My First JavaScript Animation</h1>
<div id="container">
<div id="animate"></div>
</div>
</body>
</html>