body {
  color: #555;
  font-size: 1rem;
  position: relative;
}

.lightbox {
  background: rgba(0, 0, 0, .75);
  visibility: hidden;
  opacity: 0;
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
}

#lightbox1:target  {
  visibility: visible;
  opacity: 1;
  transition: opacity .5s ease;
}

.lightbox-content {
  padding: 2rem;
  width: 600px;
  background: #fff;
  border-radius: 1rem;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

a.lightbox-close {
  color: #666;
  font-size: .75rem;
  text-decoration: none;
  position: absolute;
  top: .75rem;
  right: 1.5rem;
}