.lightbox {
  position: fixed;
  top: 0; left: 0;
  width: 100vw; height: 100vh;
  background: rgba(0,0,0,0.8);
  display: none;
  justify-content: center;
  align-items: center;
  z-index: 10000;
}
.lightbox img {
  max-width: 90vw;
  max-height: 90vh;
  box-shadow: 0 0 10px #fff;
}