css/css-flexbox/position-fixed-001.html

<!DOCTYPE html>
<html>
<title>CSS Flexbox: flex-direction: column in fixed-positioned flexboxes.</title>
<link rel="help" href="https://drafts.csswg.org/css-flexbox/#flex-direction-property">
<link rel="help" href="https://drafts.csswg.org/css-position/#position-property">
<link rel="match" href="reference/position-fixed-001-ref.html">
<link rel="help" href="https://crbug.com/604346"/>
<meta name="assert" content="This test ensures that widths are always definite for inner flexboxes that are nested inside fixed-positioned flexboxes using 'flex-direction: column'."/>

<style>
.fixed-pos{
  position: fixed;
  background: red;
}

.inner {
  width: 100%;
  background: green;
}

.flexbox {
  display: flex;
}

.column {
  flex-direction: column;
}
</style>

<body>

<p>You should see no red.</p>

<div class="fixed-pos" >
  <div class="flexbox column">

    <div class="flexbox">
      <div class="inner">
        XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
      </div>
    </div>

    <div class="flexbox">
      <div class="inner">
        YYYY
      </div>
    </div>

  </div>
</div>

</body>
</html>