* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: system-ui, sans-serif;
  background: #f7f7f7;
  color: #222;
}

header {
  padding: 20px;
  text-align: center;
  background: white;
  border-bottom: 1px solid #ddd;
}

nav {
  margin-top: 10px;
}

nav button {
  margin: 4px;
  padding: 8px 14px;
  border: 1px solid #ccc;
  background: white;
  cursor: pointer;
}

nav button.active {
  background: #222;
  color: white;
}

#gallery {
  max-width: 1200px;
  margin: 30px auto;
  padding: 0 20px;
  columns: 3;
  column-gap: 16px;
}

.item {
  break-inside: avoid;
  margin-bottom: 16px;
}

.item img {
  width: 100%;
  display: block;
  border-radius: 4px;
  cursor: pointer;
}

@media (max-width: 900px) {
  #gallery { columns: 2; }
}

@media (max-width: 500px) {
  #gallery { columns: 1; }
}

/* Lightbox */
#lightbox {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.9);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 1000;
}

#lightbox img {
  max-width: 90%;
  max-height: 90%;
}

#lightbox .close {
  position: absolute;
  top: 20px;
  right: 30px;
  font-size: 32px;
  color: white;
  cursor: pointer;
}