<!DOCTYPE html>
<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
<link rel="help" href="https://www.w3.org/TR/CSS22/visudet.html#blockwidth">
<style>
  html {
      width: 100px;
      margin-left: auto;
  }
  body { /* Just to make testharness display nicely. */
      position: absolute;
      left: 0;
      right: 0;
  }
</style>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
  test(()=> {
      var viewport_width = window.innerWidth;
      var html = document.documentElement;
      assert_equals(html.offsetLeft, viewport_width - 100);
  }, "Root element auto margins resolve");
</script>
