html inside textarea
<textarea rows="20" cols="50" class="txtarea">
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<title></title>
</head>
<body>
<h1>This is a basic html</h1>
</body>
</html>
</textarea>
<style>
.txtarea{
/* Your Style Here */
}
</style>