<!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>