index.html

<!doctype html>
<html lang="en">
  <head>
    <!-- Required meta tags -->
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    ,<link rel="stylesheet" href="/css/custom.css">

    <title>Hello, world!</title>
  </head>
  <body>
    <script src="/node_modules/bootstrap/dist/js/bootstrap.min.js"></script>
    <div class="container">
    <div class="card" style="width: 18rem;">
      <div class="card-body">
        <h5 class="card-title">Card title</h5>
        <h6 class="card-subtitle mb-2 text-muted">Card subtitle</h6>
        <p class="card-text">Some quick example text to build on the card title and make up the bulk of the card's content.</p>
        <a href="#" class="card-link">Card link</a>
        <a href="#" class="card-link">Another link</a>
      </div>
    </div>
  </div>
  </body>
</html>