0.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Test CSS</title>
    <!-- internal styling -->
    <style>
        h2 {
            color: lightblue;
            background-color: lightcoral;
        }
    </style>
    <!-- external styling -->
    <link rel="stylesheet" type="text/css" href="0.css">
</head>
<body>
    <!-- inline styling -->
    <h1 style="color:red; background-color: yellow;">
        Ini heading 1
    </h1>
    <h2>Ini heading 2</h2>
    <h3>Ini heading 3</h3> 
</body>
</html>