.sub-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(245, 243, 238, 0.9);
  backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px min(4vw, 20px);
  border-bottom: 1px solid var(--line);
}

.sub-header h1 {
  margin: 0;
  font-size: clamp(1.1rem, 3vw, 1.5rem);
}

.back-link {
  color: var(--accent);
  font-weight: 700;
}

.sort-bar {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
  flex-wrap: wrap;
}

.sort-label {
  color: var(--ink-soft);
  font-size: 0.95rem;
}

.sort-btn {
  border: 1px solid var(--line);
  background: #fff;
  color: var(--ink-soft);
  border-radius: 999px;
  padding: 6px 12px;
  cursor: pointer;
}

.sort-btn.is-active {
  border-color: var(--accent);
  color: var(--accent);
  font-weight: 700;
  background: #fff5ef;
}

.waterfall {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
  align-items: start;
}

.waterfall-col {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.photo-item {
  border-radius: 12px;
  overflow: hidden;
  border: 1px solid var(--line);
  background: #fff;
}

.photo-item img {
  width: 100%;
  display: block;
}

.hint {
  text-align: center;
  color: var(--ink-soft);
}

.viewer {
  border: none;
  border-radius: 12px;
  width: min(960px, 92vw);
  padding: 8px;
}

.viewer::backdrop {
  background: rgba(0, 0, 0, 0.7);
}

.viewer img {
  width: 100%;
  max-height: 75vh;
  object-fit: contain;
  background: #000;
}

.viewer-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 8px;
}

.back-viewer-btn,
.download-btn {
  border: none;
  border-radius: 8px;
  padding: 8px 12px;
  cursor: pointer;
}

.back-viewer-btn {
  background: #3d3d3d;
  color: #fff;
}

.download-btn {
  display: inline-block;
  background: var(--accent);
  color: #fff;
}

.photo-meta {
  margin-top: 8px;
  color: var(--ink-soft);
  font-size: 0.9rem;
  line-height: 1.5;
  white-space: pre-line;
}

@media (max-width: 900px) {
  .waterfall {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (max-width: 640px) {
  .waterfall {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}