css/css-position/position-absolute-center-002.html

<!DOCTYPE html>
<link rel="help" href="https://github.com/w3c/csswg-drafts/issues/4659">
<link rel="help" href="https://drafts.csswg.org/css-align-3/#abspos-sizing">
<link rel="match" href="../reference/ref-filled-green-100px-square.xht">
<meta name="assert" content="The available space for a box with center alignment is double the distance between the center of the static position rectangle and the closest edge of the containing block in the relevant axis.">
<style>
#containing-block {
  position: relative;
  width: 100px;
  height: 100px;
  background: red;
  display: flex;
}

#containing-block > div {
  flex-grow: 1;
}

#inner-flex {
  display: flex;
  align-items: center;
}

span {
  display: inline-block;
  inline-size: 50px;
  block-size: 10px;
}
</style>
<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
<div id="containing-block" style="flex-direction: column;">
  <div id="inner-flex" style="margin: 10px; width: 100px;">
    <div style="position: absolute; left: 0; width: 100px; background: green; writing-mode: vertical-rl;">
      <span></span>
      <span></span>
    </div>
  </div>
  <div style="width: 100px; background: green;"></div>
</div>