<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Flexbox Test: gap - horizontal with LR vertical writing mode</title>
<link rel="author" title="Adam Argyle" href="mailto:argyle@google.com">
<style>
  body {
    writing-mode: vertical-lr;
  }

  section {
    background-color: green;
    block-size: 100px;
    display: flex;
  }
  section > div{
    background-color: grey;
    flex: 1 1 auto;
  }
  section > div:not(:first-child) {
    margin-inline-start: 20px;
  }
</style>
<body>
  <p>Test passes if there is <strong>a green line between boxes</strong>.</p>
  <section>
    <div></div>
    <div></div>
    <div></div>
  </section>
</body>