:root {
  --sidebar-bg: #1e1b4b;
  --sidebar-bg-hover: #312e81;
  --sidebar-active: #6366f1;
  --sidebar-text: #e2e8f0;
  --sidebar-text-secondary: #94a3b8;
  --content-bg: #f8fafc;
  --content-bg-secondary: #ffffff;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;
  --border-color: #e2e8f0;
  --accent-primary: #6366f1;
  --accent-secondary: #8b5cf6;
  --success-color: #22c55e;
  --danger-color: #ef4444;
  --warning-color: #f59e0b;
  --info-color: #3b82f6;
  --radius: 12px;
  --radius-sm: 8px;
  --radius-lg: 16px;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.05);
  --font-family: 'Inter', 'Segoe UI', system-ui, -apple-system, sans-serif;
}

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

html, body {
  height: 100%;
}

body {
  font-family: var(--font-family);
  background-color: var(--content-bg);
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--accent-primary);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--accent-secondary);
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.card {
  background-color: var(--content-bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 20px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
  font-family: var(--font-family);
  gap: 6px;
}

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

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

.btn-primary:hover:not(:disabled) {
  background-color: var(--accent-secondary);
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
  transform: translateY(-1px);
}

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

.btn-danger:hover:not(:disabled) {
  background-color: #dc2626;
  box-shadow: 0 4px 12px rgba(239, 68, 68, 0.3);
}

.btn-secondary {
  background-color: #f1f5f9;
  color: var(--text-primary);
}

.btn-secondary:hover:not(:disabled) {
  background-color: #e2e8f0;
}

.btn-outline {
  background-color: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-primary);
}

.btn-outline:hover:not(:disabled) {
  border-color: var(--accent-primary);
  color: var(--accent-primary);
  background-color: rgba(99, 102, 241, 0.05);
}

.input, select, textarea {
  width: 100%;
  padding: 10px 14px;
  background-color: var(--content-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-size: 14px;
  font-family: var(--font-family);
  transition: all 0.2s ease;
  outline: none;
}

.input:focus, select:focus, textarea:focus {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.input::placeholder, textarea::placeholder {
  color: var(--text-muted);
}

select {
  cursor: pointer;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%2364748b' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 36px;
}

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

.form-group {
  margin-bottom: 16px;
}

.form-group label {
  display: block;
  margin-bottom: 6px;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-primary);
}

.table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}

.table th,
.table td {
  padding: 12px 16px;
  text-align: left;
  border-bottom: 1px solid var(--border-color);
}

.table th {
  font-weight: 600;
  color: var(--text-secondary);
  background-color: var(--content-bg);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.table tbody tr {
  transition: background-color 0.15s ease;
}

.table tbody tr:hover {
  background-color: rgba(99, 102, 241, 0.03);
}

.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: all 0.2s ease;
}

.modal-overlay.active {
  opacity: 1;
  visibility: visible;
}

.modal {
  background-color: var(--content-bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 24px;
  max-width: 500px;
  width: 90%;
  max-height: 90vh;
  overflow-y: auto;
  transform: scale(0.95);
  transition: transform 0.2s ease;
  box-shadow: var(--shadow-lg);
}

.modal-overlay.active .modal {
  transform: scale(1);
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
}

.modal-title {
  font-size: 18px;
  font-weight: 600;
  color: var(--text-primary);
}

.modal-close {
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 24px;
  cursor: pointer;
  line-height: 1;
  transition: color 0.2s ease;
  padding: 4px;
}

.modal-close:hover {
  color: var(--text-primary);
}

.toast-container {
  position: fixed;
  top: 20px;
  right: 20px;
  z-index: 2000;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.toast {
  padding: 12px 20px;
  border-radius: var(--radius-sm);
  color: white;
  font-size: 14px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  animation: slideIn 0.3s ease;
  min-width: 250px;
}

.toast.info {
  background-color: var(--info-color);
}

.toast.success {
  background-color: var(--success-color);
}

.toast.error {
  background-color: var(--danger-color);
}

.toast.warning {
  background-color: var(--warning-color);
}

@keyframes slideIn {
  from {
    transform: translateX(100%);
    opacity: 0;
  }
  to {
    transform: translateX(0);
    opacity: 1;
  }
}

@keyframes slideOut {
  from {
    transform: translateX(0);
    opacity: 1;
  }
  to {
    transform: translateX(100%);
    opacity: 0;
  }
}

.sidebar {
  position: fixed;
  left: 0;
  top: 0;
  width: 250px;
  height: 100vh;
  background-color: var(--sidebar-bg);
  display: flex;
  flex-direction: column;
  z-index: 100;
  transition: width 0.3s ease;
}

.sidebar.collapsed {
  width: 70px;
}

.sidebar-logo {
  padding: 24px;
  display: flex;
  align-items: center;
  gap: 12px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

.sidebar-logo-icon {
  width: 40px;
  height: 40px;
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  color: white;
  flex-shrink: 0;
}

.sidebar-logo-text {
  font-size: 18px;
  font-weight: 700;
  color: white;
  white-space: nowrap;
}

.sidebar.collapsed .sidebar-logo-text {
  display: none;
}

.sidebar-nav {
  flex: 1;
  padding: 16px 0;
  overflow-y: auto;
}

.sidebar-link {
  display: flex;
  align-items: center;
  padding: 12px 24px;
  color: var(--sidebar-text-secondary);
  font-size: 14px;
  font-weight: 500;
  transition: all 0.2s ease;
  gap: 12px;
  white-space: nowrap;
}

.sidebar-link .icon {
  font-size: 18px;
  flex-shrink: 0;
  width: 20px;
  text-align: center;
}

.sidebar-link:hover {
  color: var(--sidebar-text);
  background-color: var(--sidebar-bg-hover);
}

.sidebar-link.active {
  color: white;
  background-color: var(--sidebar-active);
}

.sidebar.collapsed .sidebar-link span {
  display: none;
}

.sidebar.collapsed .sidebar-link {
  padding: 12px;
  justify-content: center;
}

.sidebar-footer {
  padding: 16px;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  display: flex;
  align-items: center;
  gap: 12px;
}

.sidebar-user-avatar {
  width: 36px;
  height: 36px;
  background: linear-gradient(135deg, #8b5cf6, #ec4899);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 14px;
  font-weight: 600;
  flex-shrink: 0;
}

.sidebar-user-info {
  flex: 1;
  min-width: 0;
}

.sidebar-username {
  font-size: 14px;
  font-weight: 500;
  color: white;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.sidebar-role {
  font-size: 12px;
  color: var(--sidebar-text-secondary);
}

.sidebar.collapsed .sidebar-user-info {
  display: none;
}

.sidebar-toggle {
  position: absolute;
  right: -12px;
  top: 24px;
  width: 24px;
  height: 24px;
  background-color: var(--content-bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  color: var(--text-secondary);
  transition: all 0.2s ease;
  z-index: 101;
}

.sidebar-toggle:hover {
  background-color: var(--accent-primary);
  color: white;
  border-color: var(--accent-primary);
}

.header {
  position: fixed;
  top: 0;
  left: 250px;
  right: 0;
  height: 64px;
  background-color: var(--content-bg-secondary);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
  z-index: 99;
  transition: left 0.3s ease;
}

.sidebar.collapsed ~ .header {
  left: 70px;
}

.header-title {
  font-size: 20px;
  font-weight: 600;
  color: var(--text-primary);
}

.header-subtitle {
  font-size: 14px;
  color: var(--text-muted);
  margin-top: 2px;
}

.header-user {
  position: relative;
  display: flex;
  align-items: center;
  gap: 16px;
  cursor: pointer;
}

.header-user-info {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  padding: 4px 8px;
  border-radius: var(--radius-sm);
  transition: background 0.2s ease;
}

.header-user-info:hover {
  background: rgba(255, 255, 255, 0.05);
}

.header-username {
  font-size: 14px;
  font-weight: 500;
  color: var(--text-primary);
}

.header-role {
  font-size: 12px;
  color: var(--text-muted);
}

/* 用户下拉菜单 */
.user-dropdown {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  min-width: 160px;
  background: var(--content-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-8px);
  transition: all 0.2s ease;
  z-index: 1000;
  overflow: hidden;
}

.user-dropdown.show {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.user-dropdown-header {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border-color);
  background: rgba(0, 0, 0, 0.2);
}

.user-dropdown-name {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
}

.user-dropdown-role {
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 2px;
}

.user-dropdown-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 16px;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s ease;
  font-size: 14px;
}

.user-dropdown-item:hover {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-primary);
}

.user-dropdown-item.danger {
  color: var(--danger-color);
}

.user-dropdown-item.danger:hover {
  background: rgba(239, 68, 68, 0.1);
}

.main {
  margin-left: 250px;
  margin-top: 64px;
  padding: 24px;
  min-height: calc(100vh - 64px);
  transition: margin-left 0.3s ease;
}

.sidebar.collapsed ~ .main {
  margin-left: 70px;
}

.status-badge {
  display: inline-flex;
  align-items: center;
  padding: 4px 12px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 500;
}

.status-badge.success {
  background-color: rgba(34, 197, 94, 0.1);
  color: var(--success-color);
}

.status-badge.danger {
  background-color: rgba(239, 68, 68, 0.1);
  color: var(--danger-color);
}

.status-badge.warning {
  background-color: rgba(245, 158, 11, 0.1);
  color: var(--warning-color);
}

.status-badge.info {
  background-color: rgba(59, 130, 246, 0.1);
  color: var(--info-color);
}

.auth-page {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  background: linear-gradient(135deg, var(--sidebar-bg) 0%, #312e81 100%);
  position: relative;
  overflow: hidden;
}

.auth-page::before {
  content: '';
  position: absolute;
  width: 600px;
  height: 600px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.15) 0%, transparent 70%);
  top: -200px;
  right: -200px;
}

.auth-page::after {
  content: '';
  position: absolute;
  width: 500px;
  height: 500px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(139, 92, 246, 0.1) 0%, transparent 70%);
  bottom: -150px;
  left: -150px;
}

.auth-card {
  width: 100%;
  max-width: 420px;
  position: relative;
  z-index: 1;
  background-color: white;
  border-radius: var(--radius-lg);
  box-shadow: 0 25px 50px rgba(0, 0, 0, 0.2);
}

.auth-logo {
  text-align: center;
  margin-bottom: 32px;
  padding-top: 24px;
}

.auth-logo-icon {
  width: 64px;
  height: 64px;
  margin: 0 auto 16px;
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 32px;
  color: white;
  box-shadow: 0 10px 30px rgba(99, 102, 241, 0.3);
}

.auth-title {
  font-size: 24px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.auth-subtitle {
  font-size: 14px;
  color: var(--text-muted);
}

.auth-form {
  padding: 0 24px 24px;
}

.auth-form .btn {
  width: 100%;
  margin-top: 8px;
  padding: 12px;
  font-size: 15px;
}

.auth-footer {
  text-align: center;
  margin-top: 20px;
  font-size: 14px;
  color: var(--text-muted);
}

.page-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 24px;
}

.page-title {
  font-size: 24px;
  font-weight: 700;
  color: var(--text-primary);
}

.page-subtitle {
  font-size: 14px;
  color: var(--text-muted);
  margin-top: 4px;
}

.page-actions {
  display: flex;
  gap: 10px;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  margin-bottom: 24px;
}

.stat-card {
  background-color: var(--content-bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 24px;
  position: relative;
  overflow: hidden;
}

.stat-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: var(--accent-primary);
}

.stat-card.success::before { background: var(--success-color); }
.stat-card.danger::before { background: var(--danger-color); }
.stat-card.warning::before { background: var(--warning-color); }
.stat-card.info::before { background: var(--info-color); }

.stat-value {
  font-size: 36px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.stat-label {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 8px;
}

.stat-change {
  font-size: 13px;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 4px;
}

.stat-change.positive {
  color: var(--success-color);
}

.stat-change.negative {
  color: var(--danger-color);
}

.filters {
  display: flex;
  gap: 12px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.filters .input,
.filters select {
  width: auto;
  min-width: 150px;
}

.pagination {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 8px;
  margin-top: 20px;
}

.pagination button {
  padding: 8px 14px;
  background-color: var(--content-bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  cursor: pointer;
  font-size: 14px;
  transition: all 0.2s ease;
}

.pagination button:hover:not(:disabled) {
  border-color: var(--accent-primary);
  color: var(--accent-primary);
}

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

.pagination button.active {
  background-color: var(--accent-primary);
  border-color: var(--accent-primary);
  color: white;
}

.face-upload-area {
  border: 2px dashed var(--border-color);
  border-radius: var(--radius);
  padding: 32px;
  text-align: center;
  cursor: pointer;
  transition: all 0.2s ease;
  background-color: var(--content-bg);
}

.face-upload-area:hover {
  border-color: var(--accent-primary);
  background-color: rgba(99, 102, 241, 0.03);
}

.face-upload-area.has-file {
  border-color: var(--success-color);
  background-color: rgba(34, 197, 94, 0.03);
}

.face-preview {
  max-width: 200px;
  max-height: 200px;
  border-radius: var(--radius-sm);
  margin-top: 12px;
}

@media (max-width: 768px) {
  .sidebar {
    transform: translateX(-100%);
    transition: transform 0.3s ease;
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .header {
    left: 0;
  }

  .main {
    margin-left: 0;
  }

  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .table {
    font-size: 12px;
  }

  .table th,
  .table td {
    padding: 8px 10px;
  }

  .filters {
    flex-direction: column;
  }

  .filters .input,
  .filters select {
    width: 100%;
  }

  .page-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }

  .page-actions {
    width: 100%;
  }

  .page-actions .btn {
    flex: 1;
  }

  .sidebar-toggle {
    display: none;
  }
}

@media (max-width: 480px) {
  .stats-grid {
    grid-template-columns: 1fr;
  }

  .auth-card {
    padding: 20px;
  }

  .auth-title {
    font-size: 20px;
  }

  .stat-value {
    font-size: 28px;
  }
}

.table-container {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.table-container::-webkit-scrollbar {
  height: 6px;
}

.table-container::-webkit-scrollbar-track {
  background: var(--content-bg);
  border-radius: 3px;
}

.table-container::-webkit-scrollbar-thumb {
  background: var(--border-color);
  border-radius: 3px;
}

.table-container::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  font-size: 24px;
  cursor: pointer;
  color: var(--text-primary);
  padding: 8px;
}

.sidebar-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.5);
  z-index: 95;
  opacity: 0;
  transition: opacity 0.3s ease;
}

.sidebar-overlay.active {
  opacity: 1;
}

@media (max-width: 768px) {
  .mobile-menu-btn {
    display: flex;
    align-items: center;
    justify-content: center;
  }

  .sidebar-overlay {
    display: block;
  }

  .modal {
    max-width: 100%;
    width: 100%;
    max-height: 100vh;
    border-radius: 0;
    padding: 20px;
  }

  .btn {
    width: 100%;
  }

  .input, select, textarea {
    min-width: 100%;
  }

  .table-container {
    margin: 0 -24px;
    padding: 0 24px;
  }

  .table {
    min-width: 600px;
  }

  .filters {
    flex-direction: column;
    gap: 12px;
  }

  .filters .input,
  .filters select {
    width: 100%;
    min-width: 100%;
  }

  .filters .date-range {
    flex-direction: column;
    align-items: flex-start;
    width: 100%;
  }

  .filters .date-range input[type="date"] {
    width: 100%;
  }

  .page-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }

  .page-actions {
    width: 100%;
    flex-direction: column;
    gap: 10px;
  }

  .page-actions .btn {
    width: 100%;
  }

  .main {
    padding: 16px;
  }

  .card {
    padding: 16px;
  }

  .recent-item {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }

  .recent-item .rtime {
    font-size: 11px;
  }

  .search-box {
    flex-direction: column;
  }

  .search-box .input {
    width: 100%;
  }

  .search-result-item {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }

  .student-actions {
    flex-direction: column;
  }

  .student-actions .btn {
    width: 100%;
  }

  .back-btn {
    width: 36px;
    height: 36px;
    font-size: 16px;
  }

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

  .video-container {
    height: 280px;
  }

  .record-layout {
    grid-template-columns: 1fr;
    height: auto;
  }

  .bottom-stats {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .recent-list {
    max-height: 200px;
  }

  .action-btns {
    flex-direction: column;
    gap: 6px;
  }

  .action-btns .btn {
    padding: 8px 10px;
    font-size: 12px;
  }

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

  .period-actions {
    flex-direction: column;
  }

  .period-actions .btn {
    width: 100%;
  }

  .quick-actions {
    grid-template-columns: 1fr;
  }

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