<!DOCTYPE html>
<link rel="help" href="https://drafts.csswg.org/css-align-3/#baseline-rules">
<style>
#target {
  display: grid;
  grid-template: 50px 50px 50px / 50px 50px;
  grid-auto-flow: column;
  align-items: last baseline;
  width: 200px;
  border: solid 3px;
  position: relative;
  line-height: 0;
  font-size: 20px;
}
span {
  display: inline-block;
  width: 1em;
  height: 1em;
  outline: solid cyan 3px;
  outline-offset: -3px;
}
</style>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/check-layout-th.js"></script>
<body onload="checkLayout('#target > div')">

<div id="target">
  <div style="grid-area: 3 / 1; margin-bottom: 10px;" data-offset-y="100"><span></span><br><span></span></div>
  <div style="grid-area: 1 / 2 / 4 / 2;" data-offset-y="100"><span></span><br><span></span></div>
</div>
