seahub/frontend/src/css/image-file-view.css

.image-file-view {
  position: relative;
  text-align: center;
}

.image-file-view:before {
  content: ' ';
  display: inline-block;
  vertical-align: middle;
  height: 100%;
  font-size: 0;
  line-height: 0;
}

#image-view {
  padding: 1px;
  background: #fff;
  border: 1px solid #eee;
  width: auto;
  height: auto;
  max-width: calc(100% - 4px);
  max-height: calc(100% - 4px);
  font-size: 0;
  line-height: 0;
}

#img-prev,
#img-next {
  position: absolute;
  top: 48%;
  text-decoration: none;
  color: #666;
  width: 50px;
  height: 50px;
  background: #fff;
  border-radius: 100%;
  line-height: 50px;
  z-index: 1;
}

#img-prev {
  left: 15px;
}

#img-next {
  right: 15px;
}

#img-prev:hover,
#img-next:hover {
  color: #212529;
}

.image-zoomer {
  height: 24px;
}