/* ============================================================
   Design Tokens
   ============================================================ */
:root {
  --color-bg:          #f5f7fa;
  --color-surface:     #ffffff;
  --color-primary:     #4a90d9;
  --color-primary-hover: #3a7bc8;
  --color-success:     #52c41a;
  --color-danger:      #ff4d4f;
  --color-danger-hover: #e04345;
  --color-text:        #333333;
  --color-text-secondary: #888888;
  --color-border:      #e8e8e8;
  --color-border-light: #f0f0f0;

  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
                 "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  --font-size-sm:   0.875rem;
  --font-size-base: 1rem;
  --font-size-lg:   1.125rem;
  --font-size-xl:   1.5rem;
  --font-size-2xl:  2rem;

  --space-xs:  0.25rem;
  --space-sm:  0.5rem;
  --space-md:  1rem;
  --space-lg:  1.5rem;
  --space-xl:  2rem;
  --space-2xl: 3rem;

  --container-max: 1200px;
  --sidebar-width: 220px;
  --border-radius: 6px;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 2px 8px rgba(0, 0, 0, 0.12);
  --transition: 0.2s ease;
}

/* ============================================================
   Base
   ============================================================ */
html {
  font-size: 16px;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  min-height: 100vh;
}

.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: var(--space-lg) var(--space-xl);
}

.page-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-xl);
  flex-wrap: wrap;
  gap: var(--space-md);
}

.page-header h1 {
  font-size: var(--font-size-xl);
  font-weight: 600;
}

.text-secondary {
  color: var(--color-text-secondary);
}

/* ============================================================
   Navbar
   ============================================================ */
.navbar {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  height: 56px;
  position: sticky;
  top: 0;
  z-index: 100;
}

.navbar-inner {
  max-width: var(--container-max);
  margin: 0 auto;
  height: 100%;
  display: flex;
  align-items: center;
  padding: 0 var(--space-xl);
  gap: var(--space-xl);
}

.navbar-brand {
  font-size: var(--font-size-lg);
  font-weight: 700;
  color: var(--color-primary);
  white-space: nowrap;
}

.navbar-nav {
  display: flex;
  gap: var(--space-lg);
  flex: 1;
}

.navbar-nav a {
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  transition: color var(--transition);
  position: relative;
}

.navbar-nav a:hover {
  color: var(--color-primary);
}

.navbar-nav a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--color-primary);
  transition: width var(--transition);
}

.navbar-nav a:hover::after {
  width: 100%;
}

.navbar-user {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  white-space: nowrap;
}

.navbar-username {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

/* ============================================================
   Footer
   ============================================================ */
.footer {
  text-align: center;
  padding: var(--space-xl);
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  border-top: 1px solid var(--color-border);
  margin-top: var(--space-2xl);
}

/* ============================================================
   Buttons
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 8px 20px;
  border-radius: var(--border-radius);
  font-size: var(--font-size-sm);
  font-weight: 500;
  transition: all var(--transition);
  border: 1px solid transparent;
  gap: var(--space-xs);
  white-space: nowrap;
  line-height: 1.5;
}

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

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

.btn-danger {
  background: transparent;
  color: var(--color-danger);
  border-color: var(--color-danger);
}

.btn-danger:hover {
  background: var(--color-danger);
  color: #fff;
}

.btn-ghost {
  background: transparent;
  color: var(--color-text-secondary);
  border-color: var(--color-border);
}

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

.btn-sm {
  padding: 4px 12px;
  font-size: 0.8125rem;
}

.btn-block {
  width: 100%;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* ============================================================
   Cards
   ============================================================ */
.card {
  background: var(--color-surface);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-sm);
  padding: var(--space-lg);
}

/* ============================================================
   Forms
   ============================================================ */
.form-group {
  margin-bottom: var(--space-md);
}

.form-label {
  display: block;
  margin-bottom: 6px;
  font-weight: 500;
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

.form-input,
.form-textarea,
.form-select {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius);
  font-size: var(--font-size-base);
  background: var(--color-surface);
  transition: border-color var(--transition), box-shadow var(--transition);
  color: var(--color-text);
}

.form-input:focus,
.form-textarea:focus,
.form-select:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(74, 144, 217, 0.15);
}

.form-textarea {
  resize: vertical;
  min-height: 80px;
}

/* ============================================================
   Alerts / Flash Messages
   ============================================================ */
.messages-container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: var(--space-md) var(--space-xl) 0;
}

.alert {
  padding: 12px 16px;
  border-radius: var(--border-radius);
  margin-bottom: var(--space-sm);
  font-size: var(--font-size-sm);
  border: 1px solid transparent;
}

.alert-success {
  background: #f6ffed;
  border-color: #b7eb8f;
  color: #389e0d;
}

.alert-error {
  background: #fff2f0;
  border-color: #ffccc7;
  color: #cf1322;
}

/* ============================================================
   Album Grid
   ============================================================ */
.album-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: var(--space-lg);
}

.album-card {
  background: var(--color-surface);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  transition: transform var(--transition), box-shadow var(--transition);
  display: block;
}

.album-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.album-cover {
  width: 100%;
  aspect-ratio: 4 / 3;
  overflow: hidden;
  background: var(--color-border-light);
}

.album-cover img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.album-cover-placeholder {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
}

.album-info {
  padding: var(--space-md);
}

.album-title {
  font-size: var(--font-size-base);
  font-weight: 600;
  margin-bottom: var(--space-xs);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.album-count {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

.album-description {
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  margin-top: var(--space-sm);
}

/* ============================================================
   Photo Grid
   ============================================================ */
.photo-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: var(--space-md);
}

.photo-item {
  position: relative;
  aspect-ratio: 1;
  overflow: hidden;
  border-radius: var(--border-radius);
  background: var(--color-border-light);
  cursor: pointer;
}

.photo-item img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition);
}

.photo-item:hover img {
  transform: scale(1.05);
}

.photo-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.3);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: opacity var(--transition);
}

.photo-item:hover .photo-overlay {
  opacity: 1;
}

.photo-download-icon {
  color: #fff;
  font-size: var(--font-size-xl);
}

/* ============================================================
   Breadcrumb
   ============================================================ */
.breadcrumb {
  display: flex;
  gap: var(--space-sm);
  align-items: center;
  margin-bottom: var(--space-lg);
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

.breadcrumb a:hover {
  color: var(--color-primary);
}

.breadcrumb-sep {
  color: var(--color-border);
}

/* ============================================================
   Photo Detail
   ============================================================ */
.photo-detail-container {
  max-width: 960px;
  margin: 0 auto;
}

.photo-detail-nav {
  display: flex;
  justify-content: space-between;
  margin-bottom: var(--space-md);
}

.photo-detail-image {
  background: var(--color-surface);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 300px;
}

.photo-detail-image img {
  max-width: 100%;
  max-height: 70vh;
  object-fit: contain;
}

.photo-detail-actions {
  display: flex;
  gap: var(--space-md);
  justify-content: center;
  margin-top: var(--space-lg);
}

.photo-detail-meta {
  display: flex;
  gap: var(--space-xl);
  padding-top: var(--space-lg);
  margin-top: var(--space-lg);
  border-top: 1px solid var(--color-border-light);
  flex-wrap: wrap;
}

.meta-item {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.meta-label {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

.meta-value {
  font-size: var(--font-size-base);
  font-weight: 500;
}

/* ============================================================
   Tables
   ============================================================ */
.table-wrapper {
  overflow-x: auto;
}

.table {
  width: 100%;
  border-collapse: collapse;
  background: var(--color-surface);
  border-radius: var(--border-radius);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.table th {
  background: #fafafa;
  font-weight: 600;
  font-size: var(--font-size-sm);
  text-align: left;
  padding: 12px 16px;
  border-bottom: 2px solid var(--color-border);
  white-space: nowrap;
}

.table td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--color-border-light);
  font-size: var(--font-size-sm);
}

.table tr:last-child td {
  border-bottom: none;
}

.table tr:hover td {
  background: #fafafa;
}

.actions {
  display: flex;
  gap: var(--space-sm);
  align-items: center;
}

/* ============================================================
   Badges
   ============================================================ */
.badge {
  display: inline-block;
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.8125rem;
  font-weight: 500;
}

.badge-admin {
  background: #e6f0ff;
  color: #2e6bb8;
}

.badge-user {
  background: #f0f0f0;
  color: #888;
}

/* ============================================================
   Stats Grid
   ============================================================ */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
}

.stat-card {
  background: var(--color-surface);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-sm);
  padding: var(--space-xl);
  text-align: center;
}

.stat-value {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  color: var(--color-primary);
}

.stat-label {
  margin-top: var(--space-sm);
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

/* ============================================================
   Admin Layout
   ============================================================ */
.admin-layout {
  display: flex;
  min-height: calc(100vh - 56px - 80px);
}

.admin-sidebar {
  width: var(--sidebar-width);
  min-width: var(--sidebar-width);
  background: var(--color-surface);
  border-right: 1px solid var(--color-border);
  padding: var(--space-lg) 0;
}

.sidebar-section {
  padding: var(--space-sm) 0;
}

.sidebar-label {
  display: block;
  padding: var(--space-sm) var(--space-lg);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  color: var(--color-text-secondary);
  letter-spacing: 0.5px;
}

.sidebar-nav a {
  display: block;
  padding: 10px var(--space-lg);
  color: var(--color-text);
  font-size: var(--font-size-sm);
  transition: all var(--transition);
  border-left: 3px solid transparent;
}

.sidebar-nav a:hover {
  background: rgba(74, 144, 217, 0.06);
  color: var(--color-primary);
}

.sidebar-nav a.active {
  background: rgba(74, 144, 217, 0.08);
  color: var(--color-primary);
  font-weight: 500;
  border-left-color: var(--color-primary);
}

.admin-content {
  flex: 1;
  padding: var(--space-lg) var(--space-xl);
  min-width: 0;
}

/* ============================================================
   Upload Zone
   ============================================================ */
.upload-zone {
  border: 2px dashed var(--color-border);
  border-radius: var(--border-radius);
  padding: var(--space-2xl);
  text-align: center;
  cursor: pointer;
  transition: all var(--transition);
  background: var(--color-bg);
}

.upload-zone:hover,
.upload-zone.dragover {
  border-color: var(--color-primary);
  background: rgba(74, 144, 217, 0.03);
}

.upload-preview {
  display: flex;
  gap: var(--space-sm);
  margin-top: var(--space-md);
  flex-wrap: wrap;
}

.upload-preview img {
  width: 80px;
  height: 80px;
  object-fit: cover;
  border-radius: 4px;
}

/* ============================================================
   Admin Photo Grid
   ============================================================ */
.photo-grid-admin {
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
}

.photo-item-admin {
  background: var(--color-surface);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}

.photo-item-admin img {
  width: 100%;
  aspect-ratio: 1;
  object-fit: cover;
}

.photo-item-actions {
  display: flex;
  gap: var(--space-sm);
  padding: var(--space-sm);
}

.photo-item-name {
  padding: 0 var(--space-sm) var(--space-sm);
  font-size: 0.75rem;
  color: var(--color-text-secondary);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* ============================================================
   Login Page
   ============================================================ */
.login-page {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: calc(100vh - 56px - 120px);
}

.login-card {
  background: var(--color-surface);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-md);
  padding: var(--space-2xl);
  width: 100%;
  max-width: 400px;
}

.login-title {
  text-align: center;
  font-size: var(--font-size-xl);
  font-weight: 600;
  margin-bottom: var(--space-xl);
  color: var(--color-text);
}

.login-form .form-group {
  margin-bottom: var(--space-lg);
}

.login-form .btn {
  margin-top: var(--space-sm);
}

/* ============================================================
   Empty State
   ============================================================ */
.empty-state {
  text-align: center;
  padding: var(--space-2xl) 0;
  color: var(--color-text-secondary);
}

.empty-state p {
  margin-bottom: var(--space-md);
  font-size: var(--font-size-lg);
}

/* ============================================================
   Error Page
   ============================================================ */
.error-page {
  text-align: center;
  padding: var(--space-2xl) 0;
}

.error-page h1 {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--space-md);
  color: var(--color-text-secondary);
}

.error-message {
  color: var(--color-text-secondary);
  margin-bottom: var(--space-lg);
}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 768px) {
  .container {
    padding: var(--space-md);
  }

  .navbar-inner {
    padding: 0 var(--space-md);
    gap: var(--space-md);
  }

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

  .album-grid {
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  }

  .admin-layout {
    flex-direction: column;
  }

  .admin-sidebar {
    width: 100%;
    min-width: unset;
    border-right: none;
    border-bottom: 1px solid var(--color-border);
    padding: var(--space-sm) 0;
  }

  .sidebar-nav {
    display: flex;
    gap: var(--space-sm);
    padding: 0 var(--space-md);
    overflow-x: auto;
    flex-wrap: wrap;
  }

  .sidebar-section {
    padding: 0;
    display: flex;
    gap: var(--space-sm);
    align-items: center;
  }

  .sidebar-label {
    padding: var(--space-xs);
    font-size: 0.7rem;
  }

  .sidebar-nav a {
    padding: 6px 12px;
    border-left: none;
    border-bottom: 2px solid transparent;
    white-space: nowrap;
  }

  .sidebar-nav a.active {
    border-left-color: transparent;
    border-bottom-color: var(--color-primary);
  }

  .admin-content {
    padding: var(--space-md);
  }

  .stats-grid {
    grid-template-columns: 1fr;
  }

  .photo-detail-meta {
    gap: var(--space-md);
  }

  .table th,
  .table td {
    padding: 8px 12px;
  }
}

@media (max-width: 480px) {
  .photo-grid {
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    gap: var(--space-sm);
  }

  .album-grid {
    grid-template-columns: 1fr 1fr;
    gap: var(--space-sm);
  }

  .page-header {
    flex-direction: column;
    align-items: flex-start;
  }

  .navbar-nav {
    display: none;
  }

  .navbar-brand {
    font-size: var(--font-size-base);
  }

  .login-card {
    padding: var(--space-xl);
  }
}