<style>
  .bd-placeholder-img {
    font-size: 1.125rem;
    text-anchor: middle;
  }

  @media (min-width: 768px) {
    .bd-placeholder-img-lg {
      font-size: 3.5rem;
    }
    #myIframe {
      width: 100%;
      height: 1000px;
    }
  }

  @media (max-width: 640px) {
    #myIframe {
      width: auto;
      height: 500px;
    }
    #viewerContainer {
      overflow-x: inherit;
    }
  }
</style>
<main role="main" class="container">
  <div class="container">
    <p><iframe id="myIframe" src="ressources/lib/web/viewer.html?file=../../../ressources/DMC_635.pdf"></iframe></p>
    <p><a class="btn btn-primary btn-lg" href="ressources/lib/web/viewer.html?file=../../../ressources/DMC_635.pdf" role="button">PDF öffnen</a></p>
 </div>
</main>