Comments

/* header */
h1 {
  color: green;
}

/* Content */
p {
  color: blue;
}

<!DOCTYPE html>
<html lang="pt-BR">
<head>
  <meta charset="UTF-8">
  <title>Document</title>
</head>
<body>
  <!-- Header -->
  <h1>Lorem ipsum</h1>

  <!-- Content -->
  <p>Lorem ipsum dolor sit amet consectetur, adipisicing elit.</p>
</body>
</html>