The :empty pseudo-class represents any element that has no children at all.

<!DOCTYPE html>
<html>

<head>
  <link href="https://fonts.googleapis.com/css?family=Work+Sans" rel="stylesheet">
  <link rel="stylesheet" href="style.css">
</head>

<body>
  <div class="Alert">
    <p>Success! Your profile has been updated.</p>
  </div>
</body>

</html>

.Alert {
  border: 3px solid darkgreen;
  margin: 1em;
  padding: 1em;
  background-color: seagreen;
  color: white;
  border-radius: 4px;
}













/* Demo styles only */
body {
  margin: 0;
  font-family: 'Work Sans', sans-serif;
  font-size: 22px;
}

p {
  margin: 0;
}