Untitled

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Css Practice 1</title>
  <link rel="stylesheet" href="style.css">
</head>
<body>
  <div id="app" class="center-your-child">
    <div class="card center-your-child">
      <div class="container">
        <button class="a">A</button>
        <button class="b">B</button>
        <button class="c">C</button>
      </div>
    </div>
  </div>
</body>
</html>