css/css-scrollbars/scrollbar-width-016.html

<!doctype html>
<meta charset="utf-8">
<title>CSS Scrollbars: scrollbar-width on scrollable areas correctly interacts with ::-webkit-scrollbar on container</title>
<link rel="author" title="Luke Warlow" href="mailto:luke@warlow.dev" />
<link rel="help" href="https://drafts.csswg.org/css-scrollbars-1/#width-compat" />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/css/support/parsing-testcommon.js"></script>
<style>
  .container {
    overflow: auto;
    height: 200px;
    width: 200px;
    margin: 1px;
    padding: 0px;
    border: none;
    background: deepskyblue;
  }

  .content {
    height: 300px;
    width: 100%;
    background: lightsalmon;
  }

  .container.auto {
    scrollbar-width: auto;
  }

  .container.auto::-webkit-scrollbar {
    display: none;
  }

  /* This is so that browsers that don't implement the WebKit prefix still pass the test */
  @supports not selector(::-webkit-scrollbar) {
    .container.auto {
      overflow: hidden;
    }
  }

  .container.thin {
    scrollbar-width: thin;
  }

  .container.thin::-webkit-scrollbar {
    display: none;
  }

  .container.none {
    scrollbar-width: none;
  }

  .container.none::-webkit-scrollbar {
    width: 20px;
    background-color: lightgray;
  }
</style>
<script>
  function performTest() {
    setup({ explicit_done: true });

    // ltr

    test(function () {
      let container = document.getElementById('container_auto');
      let content = document.getElementById('content_auto');
      assert_equals(container.scrollWidth, 200, "auto scrollWidth");
      assert_equals(container.clientWidth, 200, "auto clientWidth");
      assert_equals(container.offsetLeft, content.offsetLeft, "auto offsetLeft");
      assert_equals(container.clientWidth, content.clientWidth, "auto clientWidth");
      assert_equals(container.offsetWidth, content.offsetWidth, "auto offsetWidth");
    }, "scrollbar-width auto defers to ::-webkit-scrollbar");

    test(function () {
      let container = document.getElementById('container_thin');
      let content = document.getElementById('content_thin');
      assert_less_than(container.scrollWidth, container.offsetWidth, "thin scrollWidth");
      assert_less_than(container.clientWidth, container.offsetWidth, "thin clientWidth");
      assert_equals(container.offsetLeft, content.offsetLeft, "thin offsetLeft");
      assert_equals(container.clientWidth, content.clientWidth, "thin clientWidth");
      assert_not_equals(container.offsetWidth, content.offsetWidth, "thin offsetWidth");
    }, "scrollbar-width thin overrides ::-webkit-scrollbar");

    test(function () {
      let container = document.getElementById('container_none');
      let content = document.getElementById('content_none');
      assert_equals(container.scrollWidth, 200, "none scrollWidth");
      assert_equals(container.clientWidth, 200, "none clientWidth");
      assert_equals(container.offsetLeft, content.offsetLeft, "none offsetLeft");
      assert_equals(container.clientWidth, content.clientWidth, "none clientWidth");
      assert_equals(container.offsetWidth, content.offsetWidth, "none offsetWidth");
    }, "scrollbar-width none overrides ::-webkit-scrollbar");

    done();
  }
</script>

<body onload="performTest()">

  Test scrollbar-width: vertical scrollbar

  <div class="container auto" id="container_auto">
    <div class="content" id="content_auto">auto</div>
  </div>

  <div class="container thin" id="container_thin">
    <div class="content" id="content_thin">thin</div>
  </div>

  <div class="container none" id="container_none">
    <div class="content" id="content_none">none</div>
  </div>

</body>