 units (such as 'em') in media queries should be calculated based on the initial value of 'font-size', not based on author style declarations, such as: html { font-size: 200%; }">
  <style>
:root {
  font-size: 100000px;/* ~87ft */
}
body {
  background: red;
}
p {
  font-size: 24px;
}
  </style>
</head>
<body>
  <p>This should have a green background.</p>
  <script>
    document.body.offsetTop;
  </script>
  <style>
    @media (min-width: 1em) {
      body {
        background: green;
      }
    }
  </sty