css/css-overflow/scroll-overflow-padding-block-001.html

<!DOCTYPE html>
<title>Test "end-edges" of scrollable overflows in various writing modes</title>
<link rel="help" href="https://drafts.csswg.org/css-overflow-3/#scrollable">
<link rel="author" href="mailto:kojii@chromium.org">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
scroller {
  display: inline-block;
  overflow: auto;
  width: 100px;
  height: 100px;
  font-size: 50px;
  line-height: 1;
}
.vlr { writing-mode: vertical-lr; }
.vrl { writing-mode: vertical-rl; }
.htb > .block-start { padding-top: 200px; }
.htb > .block-end { padding-bottom: 200px; }
.vlr > .block-start { padding-left: 200px; }
.vlr > .block-end { padding-right: 200px; }
.vrl > .block-start { padding-right: 200px; }
.vrl > .block-end { padding-left: 200px; }
</style>
<body>
  <div id="log"></div>
  <div class="htb">
    <scroller class="block-start">A</scroller>
    <scroller class="block-end">A</scroller>
  </div>
  <div class="vlr">
    <scroller class="block-start">A</scroller>
    <scroller class="block-end">A</scroller>
  </div>
  <div class="vrl">
    <scroller class="block-start">A</scroller>
    <scroller class="block-end">A</scroller>
  </div>
<script>
for (let element of document.getElementsByTagName('scroller')) {
  let writing_mode = getComputedStyle(element).writingMode;
  test(() => {
    assert_equals(element.scrollWidth, element.offsetWidth, "scrollWidth");
    assert_equals(element.scrollHeight, element.offsetHeight, "scrollHeight");
  }, writing_mode + ' ' + element.className);
}
</script>
</body>