<!DOCTYPE HTML>
<style>
body {
  margin: 0;
}
#container {
  display: flex;
  align-items: stretch;
  width: 200px;
  height: 300px;
  background-color: red;
}
.item {
  background-color: green;
  border: solid thin blue;
  width: 100px;
}
</style>
<p style="height: 20px">Tests invalidation on align-items style change. Passes if there is no red.</p>
<div id="container">
  <div class="item">
    <div style="height: 100px"></div>
  </div>
  <div class="item">
    <div style="height: 150px"></div>
  </div>
</div>