.lightbox{
  position:fixed;
  top:0;left:0;width:100%;height:100%;
  background:rgba(0,0,0,0.85);
  display:flex;align-items:center;justify-content:center;
  z-index:10000;
}
.lightbox img{max-width:90%;max-height:90%;border-radius:12px;box-shadow:0 12px 40px rgba(0,0,0,0.4)}
.lightbox .close{
  position:absolute;top:30px;right:30px;font-size:48px;color:#fff;cursor:pointer;font-weight:700;
}