message: added non-media stylesheet for IE11
diff: <link rel="icon" href="images/favicon-16x16.png" sizes="16x16" type="image/png">
  <link rel="icon" href="images/favicon.png">
  <title>PptxGenJS Examples/Demo Page</title>
  + <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootswatch/4.4.0/yeti/bootstrap.min.css">
  <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootswatch/4.4.0/cyborg/bootstrap.min.css" media="(prefers-color-scheme: dark)">
  <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootswatch/4.4.0/yeti/bootstrap.min.css" media="(prefers-color-scheme: no-preference), (prefers-color-scheme: light)">
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/prism/1.15.0/themes/prism-okaidia.min.css">
  <a class="nav-link text-uppercase" id="charts-tab" data-toggle="tab" href="#charts" onclick="location.href='#charts'" role="tab" aria-controls="charts" aria-selected="false">Charts</a>
  </li>
  <li class="nav-item">
  - <a class="nav-link text-uppercase" id="images-tab" data-toggle="tab" href="#images" onclick="location.href='#images'" role="tab" aria-controls="images" aria-selected="false">Images &amp Media</a>
  + <a class="nav-link text-uppercase" id="images-tab" data-toggle="tab" href="#images" onclick="location.href='#images'" role="tab" aria-controls="images" aria-selected="false">Images &amp; Media</a>
  </li>
  <li class="nav-item">
  <a class="nav-link text-uppercase" id="shapes-tab" data-toggle="tab" href="#shapes" onclick="location.href='#shapes'" role="tab" aria-controls="shapes" aria-selected="false">Shapes &amp; Text</a>
  