.darkbox[id] {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  pointer-events: none;
  background: rgba(0,0,0,.8);
  z-index: 100;
  transition: opacity 0.3s ease-in-out;
}

.darkbox[id]:target {
  opacity: 1;
  pointer-events: auto;
}

.darkbox a {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
}

.darkbox div {
  display: flex;
  align-items: center;
  justify-content: center;
}

.darkbox div div img {
  display: block;
  max-width: 90vw;
  max-height: 90vh;
}