scrollbar-gutter-propagation-002.html

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This test has a WPT meta file that expects 1 subtest issues.
This WPT test may be referenced by the following Test IDs:
- /css/css-overflow/scrollbar-gutter-propagation-002.html - WPT Dashboard Interop Dashboard

<!doctype html>

<meta charset="utf-8">

<title>CSS Overflow: scrollbar-gutter on the root, scrolling</title>

<link rel="author" title="Felipe Erias Morandeira" href="mailto:felipeerias@igalia.com" />

<link rel="help" href="https://drafts.csswg.org/css-overflow-4/#scrollbar-gutter-property" />

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<script src="/css/support/parsing-testcommon.js"></script>

<style>

  body,

  html {

    margin: 0;

    padding: 0;

    border: none;

  :root {

    scrollbar-gutter: stable;

  #content {

    background: green;

    width: 100%;

    /* force scrolling */

    height: 200vh;

</style>

<body>

  <div id="content"></div>

  <script type="text/javascript">

    setup({ explicit_done: true });

    test(function () {

      let root = document.documentElement;

      let body = document.body;

      let content = document.getElementById('content');

      // Note: as per the spec, the clientWidth of the root element is

      // "viewport width excluding the size of a rendered scroll bar (if any)"

      // which does not take scrollbar-gutter into account.

      // Since no such special case exists for offsetWidth, this means that here

      // root.clientWidth is greater than root.offsetWidth (!!!).

      assert_less_than(root.offsetWidth, window.innerWidth, "viewport has gutter");

      assert_equals(body.offsetWidth, root.offsetWidth, "body matches root");

      assert_equals(body.clientWidth, body.offsetWidth, "body has no gutter");

      assert_equals(content.offsetWidth, body.clientWidth, "content matches body");

    }, "viewport has gutter, others do not");

    done();

  </script>

</body>