.vertical-center {
  margin: 0;
  position: absolute;
  top: 50%;
  -ms-transform: translateY(-50%);
  transform: translateY(-50%);
}

.list-group-item#rot {
  color: red;
}
.list-group-item.active#rot {
  background-color: #ac2925;
  color: white;
}
.list-group-item#ref {
  color: green;
}
.list-group-item.active#ref {
  background-color: #398439;
  color: white;
}

img.img-examples {
    display: block;
    /* max-width: 100%; */
    /* max-height: 100%; */
    width: 100%;
    height: 100%;
    margin-left: auto;
    margin-right: auto;
  }

img.bk-image {
  visibility: hidden;
  /* margin-left: auto;
  margin-right: auto; */
  /* left: 50%; */
  /* margin-left: -50px; */
  /* top: 50%;
  margin-top: -50px; */
}

canvas.labeling-tool {
    display: block;
    /* width: 100%;
    height: 100%; */
    margin-left: auto;
    margin-right: auto;
}