<!DOCTYPE html>
<html>
<head>
	<title>Margin</title>
	<style type="text/css">
		div {
			background: lightblue;
		}

		#main {
			background: #ff9600;
		}
	</style>
</head>
<body>
	<div id="main">Xin chào các bạn!</div>
</body>
</html>

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.