css/css-flexbox/flexbox-align-items-center-nested-001.html

<!doctype html>
<meta charset="utf-8">
<title>CSS Test: Flexbox nested containers with align-items: center and flexible items</title>
<link rel="match" href="flexbox-align-items-center-nested-001-ref.html">
<link rel="author" href="mailto:emilio@crisal.io" title="Emilio Cobos Álvarez">
<link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#align-items-property">
<style>
html, body { margin: 0; padding: 0; }
body {
  height: 400px;
  position: relative;
}

.container-0 {
  display: flex;
  position: absolute;
  height: 100%;
  flex-direction: column;
}

.container-1 {
  flex: 1 0 auto;
  display: flex;
  align-items: center;
}

.container-2 {
  height: 100%;
  display: flex;
  align-items: center;
}

.content {
  width: 200px;
  height: 200px;
  background: blue;
}
</style>
<body>
  <div class="container-0">
    <div class="container-1">
      <div class="container-2">
        <div class="content"></div>
      </div>
    </div>
  </div>
</body>