body {
      margin: 0;
      font-family: Arial, sans-serif;
    }

    #backBtn {
      position: fixed;
      top: 10px;
      left: 10px;
      z-index: 1000;
      padding: 10px 15px;
      background-color: #f44336;
      color: white;
      border: none;
      cursor: pointer;
      border-radius: 4px;
    }

    #fullscreenBtn {
      position: fixed;
      top: 10px;
      right: 10px;
      z-index: 1000;
      padding: 10px 15px;
      background-color: #4CAF50;
      color: white;
      border: none;
      cursor: pointer;
      border-radius: 4px;
    }

    #iframeContainer {
      width: 100%;
      height: 100vh;
    }

    iframe {
      width: 100%;
      height: 100%;
      border: none;
    }