<!doctype html>
<meta charset=utf-8>
<meta name="viewport" content="width=device-width minimum-scale=0.5">
<link rel="help" href="https://drafts.csswg.org/css-device-adapt/">
<style>
html {
  overflow: hidden;
}
body {
  margin: 0;
}
div {
  height: 200%;
  position: absolute;
}
</style>
<title></title>
<div style="width: 200%;"></div>
<div id="reference" style="width: 100%;"></div>
<script src=/resources/testharness.js></script>
<script src=/resources/testharnessreport.js></script>
<script>
'use strict';
test(() => {
  assert_equals(document.documentElement.clientWidth, reference.clientWidth,
    'documentElement clientWidth should be 100%');
}, 'documentElement clientWidth should be equal to device-width even if ' +
   'overflow:hidden region is visible');
</script>
