.container_2 {
    position: relative;
    width: 100%;
    height: 0;
    padding-bottom: 56.25%;
  }

  .video {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
  }

  .collapsible {
    background-color: #777;
    color: white;
    cursor: pointer;
    padding: 18px;
    width: 100%;
    border: none;
    text-align: left;
    outline: none;
    font-size: 15px;
  }

  .active,
  .collapsible:hover {
    background-color: #555;
  }

  .content {
    padding: 0 18px;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.2s ease-out;
    background-color: #f1f1f1;
  }

  .paperthumb {
    float: left;
    width: 120px;
    margin: 3px 10px 7px 0;
  }

  .paperdesc {
    clear: both;
  }