demo4.html

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="utf-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <meta name="description" content="">
  <meta name="author" content="Andres Galante">
  <title>Media queries</title>
  <link href="css/demo4.css" rel="stylesheet">
</head>

<body>

    <label for="checkbox">
      <input type="checkbox" id="checkbox">
    </label>
    
</body>

</html>