ls(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.o