:root {
  --bg: #f5f5f5;
  --fg: #222;
  --accent: #4a90d9;
  --border: #ddd;
  --card-bg: #fff;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1a1a2e;
    --fg: #eee;
    --accent: #6db3f2;
    --border: #333;
    --card-bg: #16213e;
  }
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.5;
}

header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px;
  border-bottom: 1px solid var(--border);
  background: var(--card-bg);
  position: sticky;
  top: 0;
  z-index: 10;
}

header h1 {
  font-size: 20px;
  font-weight: 600;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

#userDisplay {
  font-size: 13px;
  opacity: 0.7;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 12px;
  padding: 16px;
}

.thumb {
  width: 100%;
  aspect-ratio: 1;
  object-fit: cover;
  cursor: pointer;
  border-radius: 4px;
  transition: transform 0.2s ease;
  background: var(--border);
}

.thumb:hover {
  transform: scale(1.05);
}

.lightbox {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.9);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  flex-direction: column;
}

.lb-img {
  max-width: 90vw;
  max-height: 80vh;
  object-fit: contain;
}

.lb-nav {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  background: rgba(0, 0, 0, 0.5);
  color: white;
  border: none;
  padding: 12px;
  font-size: 24px;
  cursor: pointer;
  border-radius: 4px;
  transition: background 0.2s;
}

.lb-nav:hover {
  background: rgba(0, 0, 0, 0.8);
}

.lb-prev {
  left: 16px;
}

.lb-next {
  right: 16px;
}

.lb-info {
  position: absolute;
  bottom: 16px;
  left: 16px;
  right: 16px;
  background: rgba(0, 0, 0, 0.7);
  padding: 12px;
  color: white;
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  border-radius: 4px;
}

.lb-filename {
  background: rgba(255, 255, 255, 0.15);
  border: 1px solid rgba(255, 255, 255, 0.3);
  color: white;
  padding: 4px 8px;
  border-radius: 4px;
  font-size: 14px;
  flex: 1;
  min-width: 120px;
}

.lb-filename:focus {
  outline: none;
  border-color: var(--accent);
}

.lb-close {
  position: absolute;
  top: 16px;
  right: 16px;
  background: rgba(0, 0, 0, 0.5);
  color: white;
  border: none;
  font-size: 20px;
  padding: 8px 12px;
  cursor: pointer;
  border-radius: 4px;
  transition: background 0.2s;
}

.lb-close:hover {
  background: rgba(0, 0, 0, 0.8);
}

.lb-delete {
  background: #e74c3c;
  color: white;
  border: none;
  padding: 4px 12px;
  border-radius: 4px;
  cursor: pointer;
  font-size: 13px;
  transition: opacity 0.2s;
}

.lb-delete:hover {
  opacity: 0.85;
}

button {
  cursor: pointer;
  padding: 8px 16px;
  background: var(--accent);
  color: white;
  border: none;
  border-radius: 4px;
  font-size: 14px;
  transition: opacity 0.2s;
}

button:hover {
  opacity: 0.9;
}

.upload-progress {
  position: fixed;
  top: 16px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--card-bg);
  padding: 8px 16px;
  border-radius: 4px;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.15);
  z-index: 50;
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
}

.progress-bar {
  width: 200px;
  height: 4px;
  background: #eee;
  border-radius: 2px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: var(--accent);
  transition: width 0.3s ease;
  border-radius: 2px;
}

#uploadBtn {
  display: flex;
  align-items: center;
  gap: 4px;
}

@media (max-width: 600px) {
  .grid {
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 8px;
    padding: 8px;
  }
  header {
    padding: 12px;
  }
  .lb-img {
    max-height: 70vh;
  }
}