<html>
  <style type="text/css">
    div.test {
      background-color: red;
      margin: 5em;
      border-radius: 10px;
    }

    div > div {
      background-color: green;
    }
  </style>
  <body>
    <div class="test"><div>&nbsp;</div></div>
  </body>
</html>