* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  background: #fff;
  color: #111;
}

header {
  padding: 24px 16px;
  text-align: center;
}

h1 {
  margin: 0;
  font-size: 1.6rem;
  font-weight: normal;
}

.gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 8px;
  padding: 8px;
}

.gallery img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  aspect-ratio: 4 / 3;
  display: block;
  cursor: pointer;
  background: #f0f0f0;
}

.lightbox {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.9);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  cursor: zoom-out;
  z-index: 10;
}

.lightbox[hidden] {
  display: none;
}

.lightbox img {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
}

.empty {
  grid-column: 1 / -1;
  text-align: center;
  color: #888;
  padding: 40px 16px;
}