 {
    margin-top: 150px;
    margin-bottom: 175px;
    margin-left: 100px;
    margin-right: 150px;
    width: 150px;
    height: 75px;
    anchor-name: --anchor;
  }
</style>
<div id="container">
  <div id="anchored"></div>
  <div id="anchor"></div>
</div>
<script>
  function test_position_area(writing_direction, position_area, expected_offsets) {
    anchored.style.positionArea = position_area;
    test(() => {
      assert_equals(anchored.offsetLeft, expected_offsets.left, "Checking offsetLeft");
      