jitsi_corner9/css/premeeting/_prejoin-third-party.scss

$sidePanelWidth: 300px;

.prejoin-third-party {
  flex-direction: column-reverse;
  
  .content {
      height: auto;
      margin: 0 auto;

      .new-toolbox {
          width: auto;
      }
  }

  #preview {
      background-color: transparent;
      bottom: 0;
      left: 0;
      position: absolute;
      right: 0;
      top: 0;

      .avatar {
          display: none;
      }
  }

  &.splash {
      .content {
          margin-left: calc((100% - #{$prejoinDefaultContentWidth} + #{$sidePanelWidth}) / 2)
      }
  }

  &.guest {
      .content {
          margin-bottom: auto;
      }
  }
}