body {
  margin: 0;
  padding: 20px;
  background: #111;
  font-family: Arial, sans-serif;
}

/* =========================
 MASONRY CONTAINER
========================= */

.gallery {
  position: relative;
  max-width: 850px;
  margin: 0 auto;
}

/* =========================
 ITEMS (absolute positioning)
========================= */

.gallery-item {
  position: absolute;
  width: 220px;
  transition: transform 0.3s ease;
}

.gallery-item img {
  width: 100%;
  display: block;
  border-radius: 10px;
}

/* =========================
 LIGHTBOX
========================= */

.lightbox {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.95);
  justify-content: center;
  align-items: center;
  z-index: 999;
}

#lightbox-img {
  max-width: 90%;
  max-height: 90%;
  border-radius: 10px;
}

.close {
  position: fixed;
  top: 20px;
  right: 30px;
  font-size: 40px;
  color: white;
  cursor: pointer;
  z-index: 1001;
}

.nav {
  position: fixed;
  top: 50%;
  transform: translateY(-50%);
  font-size: 60px;
  color: white;
  cursor: pointer;
  user-select: none;
  z-index: 1001;
}

.prev { left: 20px; }
.next { right: 20px; }

.nav:hover,
.close:hover {
  opacity: 0.7;
}

/* Sentinel */
#sentinel {
  height: 1px;
}