css-cookbook/center.html

<!doctype html>
<html lang="en-us">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width" />
    <title>CSS Cookbook: center an element</title>
    <link rel="stylesheet" href="styles.css" />
    <style>
      .container {
        border: 2px solid rgb(75 70 74);
        border-radius: 0.5em;
      }

      .item {
        border: 2px solid rgb(95 97 110);
        border-radius: 0.5em;
        padding: 20px;
      }
    </style>

    <style class="editable">
      .container {
        height: 200px;
        display: flex;
        align-items: center;
        justify-content: center;
      }

      .item {
        width: 10em;
      }
    </style>
  </head>

  <body>
    <section class="preview">
      <div class="container">
        <div class="item">I am centered!</div>
      </div>
    </section>

    <textarea class="playable playable-css" style="height: 170px">
.container {
  height: 200px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.item {
  width: 10em;
}</textarea
    >

    <textarea class="playable playable-html" style="height: 70px">
<div class="container">
  <div class="item">I am centered!</div>
</div></textarea
    >

    <div class="playable-buttons">
      <input id="reset" type="button" value="Reset" />
    </div>
  </body>
  <script src="playable.js"></script>
</html>