web-samples/HTML/RealTimePreview.html (12 lines of code) (raw):
<!DOCTYPE html>
<html lang="en">
<head>
<link rel="stylesheet" href="realtimestyling.css">
<meta charset="UTF-8">
<title>Release Schedule</title>
</head>
<body>
<h1>Hello</h1>
<h2 class="warning">And I'm in orange</h2>
</body>
</html>