Untitled

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Reserveer</title>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css" integrity="sha384-PsH8R72JQ3SOdhVi3uxftmaW6Vc51MKb0q5P2rRUpPvrszuE4W1povHYgTpBfshb" crossorigin="anonymous">
    <script type="text/javascript"></script>
    <style>
      .backgroundPopup{
        background-color: black;
        font-size: 80px;
        color: white;
        overflow-x: hidden;
      }
      .button{
        width: 300px;
        height: 100px;
        font-size: 50px;
      }
    </style>
  </head>
  <body class="backgroundPopup">
    <div class="row">
      <div class="col-lg-offset-1 col-lg-10">
        Hoeveel wilt u reserveren?
      </div>
    </div>
    <div class="row">
      <div class="col-lg-offset-1 col-lg-10">
        <input type="number" name="reserveerAantal">
      </div>
    </div>
    <div class="row">
      <div class="col-lg-offset-1 col-lg-10">
        <button type="button" class="btn btn-danger button"><p>Sluiten</p></button>
      </div>
    </div>
  </body>
</html>