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

:root {
  --bg-primary: #0d1117;
  --bg-secondary: #161b22;
  --bg-tertiary: #21262d;
  --text-primary: #c9d1d9;
  --text-secondary: #8b949e;
  --border-color: #30363d;
  --accent-color: #58a6ff;
  --accent-hover: #79b8ff;
  --success-color: #3fb950;
  --warning-color: #d29922;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans', Helvetica, Arial, sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.5;
  min-height: 100vh;
}

.hidden {
  display: none !important;
}

/* Login Screen */
.screen {
  min-height: 100vh;
}

#login-screen {
  display: flex;
  align-items: center;
  justify-content: center;
}

.login-container {
  text-align: center;
  padding: 3rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  max-width: 400px;
}

.login-container h1 {
  margin-bottom: 0.5rem;
  font-size: 1.75rem;
}

.login-container p {
  color: var(--text-secondary);
  margin-bottom: 2rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  font-size: 1rem;
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  transition: all 0.2s;
}

.btn-primary {
  background: var(--accent-color);
  border-color: var(--accent-color);
  color: #fff;
}

.btn-primary:hover {
  background: var(--accent-hover);
  border-color: var(--accent-hover);
}

.btn-secondary {
  background: var(--bg-tertiary);
  color: var(--text-primary);
}

.btn-secondary:hover {
  background: var(--border-color);
}

/* Header */
header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 1.5rem;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.header-left h1 {
  font-size: 1.25rem;
  font-weight: 600;
}

.header-right {
  display: flex;
  align-items: center;
  gap: 1rem;
}

#ref-selector {
  padding: 0.5rem 1rem;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  color: var(--text-primary);
  font-size: 0.875rem;
  cursor: pointer;
}

#ref-selector:focus {
  outline: none;
  border-color: var(--accent-color);
}

#search {
  padding: 0.5rem 1rem;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  color: var(--text-primary);
  font-size: 0.875rem;
  width: 250px;
}

#search:focus {
  outline: none;
  border-color: var(--accent-color);
}

#search::placeholder {
  color: var(--text-secondary);
}

#user-info {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

#user-avatar {
  width: 28px;
  height: 28px;
  border-radius: 50%;
}

#user-name {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

/* Main Content */
.main-content {
  display: flex;
}

/* Sidebar Filters */
aside#filters {
  width: 250px;
  padding: 1.5rem;
  background: var(--bg-secondary);
  border-right: 1px solid var(--border-color);
  overflow-y: auto;
  flex-shrink: 0;
  position: sticky;
  top: 65px;
  height: calc(100vh - 65px);
}

.filter-section {
  margin-bottom: 1.5rem;
}

.filter-section h3 {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  color: var(--text-secondary);
  margin-bottom: 0.75rem;
  letter-spacing: 0.05em;
}

.filter-section fieldset {
  border: none;
}

.filter-section label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.375rem 0;
  font-size: 0.875rem;
  cursor: pointer;
}

.filter-section input[type="checkbox"],
.filter-section input[type="radio"] {
  width: 16px;
  height: 16px;
  accent-color: var(--accent-color);
  cursor: pointer;
}

.filter-count {
  margin-left: auto;
  font-size: 0.75rem;
  color: var(--text-secondary);
  background: var(--bg-tertiary);
  padding: 0.125rem 0.5rem;
  border-radius: 10px;
}

/* Main Gallery */
main {
  flex: 1;
  padding: 1.5rem;
  overflow-y: auto;
}

.loading {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 4rem;
  color: var(--text-secondary);
}

.spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--border-color);
  border-top-color: var(--accent-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
  margin-bottom: 1rem;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.empty-state {
  text-align: center;
  padding: 4rem;
  color: var(--text-secondary);
}

/* Gallery Grid */
#gallery {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.class-group {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.class-group-header {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border-color);
}

.snapshot-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.snapshot-card {
  position: relative;
  border: 1px solid var(--border-color);
  border-radius: 4px;
  overflow: hidden;
  cursor: pointer;
  transition: all 0.2s;
  background: var(--bg-secondary);
}

.snapshot-card:hover {
  border-color: var(--accent-color);
}

.snapshot-card img {
  display: block;
  max-width: 300px;
  max-height: 400px;
  object-fit: contain;
}

.snapshot-card .card-overlay {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  padding: 0.5rem 0.75rem;
  background: linear-gradient(transparent, rgba(0, 0, 0, 0.8));
  color: #fff;
  font-size: 0.75rem;
  opacity: 0;
  transition: opacity 0.2s;
}

.snapshot-card:hover .card-overlay {
  opacity: 1;
}

/* Lightbox */
#lightbox {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.95);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
}

.lightbox-close {
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: none;
  border: none;
  color: var(--text-primary);
  font-size: 2rem;
  cursor: pointer;
  padding: 0.5rem;
  line-height: 1;
  z-index: 1001;
}

.lightbox-close:hover {
  color: var(--accent-color);
}

.lightbox-nav {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  font-size: 2rem;
  cursor: pointer;
  padding: 1rem;
  line-height: 1;
  border-radius: 6px;
  z-index: 1001;
}

.lightbox-nav:hover {
  background: var(--border-color);
}

.lightbox-prev {
  left: 1rem;
}

.lightbox-next {
  right: 1rem;
}

.lightbox-content {
  max-width: 90vw;
  max-height: 90vh;
  display: flex;
  flex-direction: column;
  align-items: center;
}

#lightbox-image {
  max-width: 100%;
  max-height: calc(90vh - 100px);
  object-fit: contain;
  border-radius: 4px;
}

#lightbox-info {
  text-align: center;
  margin-top: 1rem;
  padding: 1rem;
  background: var(--bg-secondary);
  border-radius: 6px;
  min-width: 300px;
}

#lightbox-title {
  font-size: 1rem;
  margin-bottom: 0.5rem;
}

#lightbox-details {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

/* Responsive */
@media (max-width: 768px) {
  header {
    flex-direction: column;
    gap: 1rem;
    padding: 1rem;
  }

  .header-left, .header-right {
    width: 100%;
    justify-content: center;
    flex-wrap: wrap;
  }

  #search {
    width: 100%;
  }

  .main-content {
    flex-direction: column;
  }

  aside#filters {
    width: 100%;
    border-right: none;
    border-bottom: 1px solid var(--border-color);
  }

  .variant-grid {
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
  }
}