<!DOCTYPE html>
<!--
 | Opacity should affect the appearance of all directly contained text of
 | a node.
 |   https://www.w3.org/TR/css3-color/#transparency
 -->
<html>
<head>
  <style>
    body {
      opacity: 0.5;
      font-weight: bold;
      font-size: 50px;
    }
  </style>
</head>
<body>
  Hello there human.
</body>
</html>