ddppw

file : style.css
.header {
	color: red !important;
}


file : index.html
<!DOCTYPE html>
<html>
<head>
	<title>HTML Tutorial</title>
	<link rel="stylesheet" type="text/css" href="css/style.css">
	<style type="text/css">
		.header {
			color: green;
		}
	</style>
</head>

<body>

<h1 class="header" style="color:blue;">This is a heading</h1>
<p>This is a paragraph.</p>

</body>
</html>