<!DOCTYPE html>
<html style="font-size: 16px">
<head>

<meta name="viewport" content="width=800">
<style>
  body {
    width: 800px;
    margin: 0;
    overflow-y: hidden;
  }
</style>

</head>
<body>

<div style="font-size: 2.5rem">
    This paragraph should be autosized to 40px computed font-size (16 * 800/320),
    whereas the radio buttons below should be rendered at their default size and
    the accompanying text below should remain 16px.
    Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor
    incididunt ut labore et dolore magna aliqua.
</div>
<div>
    Select one of:<br/>
    <input type="radio" id="radio1" checked="checked"/>
    <label for="radio1">Radio1</label><br/>
    <input type="radio" id="radio2"/>
    <label for="radio2">Radio2</label><br/>
</div>

</body>
</html>