#lb-overlay { position: fixed; top: 0; left: 0; right: 0; bottom: 0;
  background: rgba(0,0,0,.8); display: none; z-index: 1000; cursor: pointer; }
#lb-overlay.open { display: flex; align-items: center; justify-content: center; }
#lb-overlay img { max-width: 90vw; max-height: 90vh; background: #fff;
  padding: 10px; box-shadow: 0 0 24px rgba(0,0,0,.6); }