Simply include a style section and a script section in the head.
<!DOCTYPE html>
<html lang='en'>
<head>
<meta charset='UTF-8'/>
<style type="text/css">
/* CSS goes here */
</style>
<script type="text/javascript">
/* Javascript goes here */
</script>
</head>
<body>
</body>
</html>
Linking CSS from a different location
<link rel="stylesheet" type="text/css" href="yourcssfile.css">
Using the script tag to include an external JavaScript file
To include an external JavaScript file, we can use the script tag with the attribute src. You've already used the src attribute when using images. The value for the src attribute should be the path to your JavaScript file.
<script type="text/javascript" src="path-to-javascript-file.js"></script>
