with html css and javascipt code example
Example 1: how to give css style in javascript
document.getElementById("myH1").style.color = "red";
Example 2: html css js
<!DOCTYPE html>
<html lang="pt-br" xml:lang="fr" xmlns="http://www.w3.org/1999/xhtml">
<head>
<link rel="stylesheet" type="text/css" href="style.css">
<title>...</title>
</head>
<body>
...
<script type="text/javascript" src="script.js"></script>
</body>
</html>