      font-size: 140%;
        background-color: #db1f48;
        color: #fff;
      }
    </style>

    <style class="editable">
      .shadow {
        box-shadow: 5px 5px 10px 2px rgb(0 0 0 / 0.8);
      }
    </style>
  </head>

  <body>
    <section class="preview">
      <div class="wrapper">
        <button class="shadow">box-shadow</button>
      </div>
    </section>

    <textarea class="playable playable-css" style="height: 100px">
.shadow {
  box-shadow: 5px 5px 10px 2px rgb(0 0 0 / .8);
}</text