<link href="cover.css" rel="stylesheet">
  </head>

  <body class="text-center">

    <div class="cover-container d-flex h-100 p-3 mx-auto flex-column">
      <header class="masthead mb-auto">
        <div class="inner">
          <h3 class="masthead-brand">Cover</h3>
          <nav class="nav nav-masthead justify-content-center">
            <a class="nav-link active" href="#">Home</a>
            <a class="nav-link" href="#">Features</a>
            <a class="nav-link" href="#">Contact</a>
          </nav