/* Base Styles */
:root {
    --primary-color: #3b82f6;
    --primary-dark: #2563eb;
    --secondary-color: #10b981;
    --secondary-dark: #059669;
    --danger-color: #ef4444;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    --border-radius: 0.5rem;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  }
  
  * {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
  }
  
  body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    line-height: 1.5;
    color: var(--gray-800);
    background-color: var(--gray-50);
    min-height: 100vh;
  }
  
  .container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
  }
  
  /* Header */
  .header {
    background-color: var(--primary-color);
    color: white;
    padding: 1.5rem 0;
  }
  
  .header h1 {
    font-size: 1.875rem;
    font-weight: 700;
    margin-bottom: 0.25rem;
  }
  
  .header p {
    color: rgba(255, 255, 255, 0.8);
  }
  
  /* Main Content */
  main {
    padding: 2rem 0;
  }
  
  .section-title {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
  }
  
  /* Cards */
  .card {
    background-color: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    padding: 1.5rem;
  }
  
  /* Form Elements */
  .form-container {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
  }
  
  .form-group {
    display: flex;
    flex-direction: column;
  }
  
  .form-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }
  
  @media (min-width: 640px) {
    .form-grid {
      grid-template-columns: repeat(2, 1fr);
    }
  }
  
  label {
    font-weight: 500;
    margin-bottom: 0.5rem;
  }
  
  input[type="text"],
  input[type="number"] {
    padding: 0.5rem 1rem;
    border: 1px solid var(--gray-300);
    border-radius: var(--border-radius);
    font-size: 1rem;
  }
  
  input[type="text"]:focus,
  input[type="number"]:focus {
    outline: 2px solid var(--primary-color);
    border-color: transparent;
  }
  
  .form-actions {
    display: flex;
    justify-content: flex-end;
    margin-top: 1rem;
  }
  
  /* Buttons */
  .button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.5rem 1rem;
    font-weight: 500;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: background-color 0.2s, transform 0.1s;
    background-color: var(--primary-color);
    color: white;
    border: none;
  }
  
  .button:hover {
    background-color: var(--primary-dark);
  }
  
  .button:active {
    transform: translateY(1px);
  }
  
  .button:disabled {
    opacity: 0.6;
    cursor: not-allowed;
  }
  
  .button-green {
    background-color: var(--secondary-color);
  }
  
  .button-green:hover {
    background-color: var(--secondary-dark);
  }
  
  .button-outline {
    background-color: white;
    color: var(--gray-700);
    border: 1px solid var(--gray-300);
  }
  
  .button-outline:hover {
    background-color: var(--gray-50);
  }
  
  .button-sm {
    padding: 0.25rem 0.5rem;
    font-size: 0.875rem;
  }
  
  /* Tabs */
  .tabs {
    margin-bottom: 2rem;
  }
  
  .tabs-list {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 0.5rem;
    margin-bottom: 1.5rem;
  }
  
  .tab-trigger {
    padding: 0.75rem;
    text-align: center;
    background-color: white;
    border: 1px solid var(--gray-200);
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: background-color 0.2s;
  }
  
  .tab-trigger:hover {
    background-color: var(--gray-50);
  }
  
  .tab-trigger.active {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
  }
  
  .tab-content {
    display: none;
    padding: 1.5rem;
    background-color: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
  }
  
  .tab-content.active {
    display: block;
  }
  
  /* Teacher Manager */
  .teacher-manager {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
  }
  
  .info-text {
    font-size: 0.875rem;
    color: var(--gray-500);
  }
  
  .note {
    font-weight: 600;
    color: var(--primary-color);
  }
  
  .input-group {
    display: flex;
    gap: 0.5rem;
  }
  
  .input-group input {
    flex: 1;
  }
  
  .teachers-container {
    border: 1px solid var(--gray-200);
    border-radius: var(--border-radius);
    overflow: hidden;
  }
  
  .empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    text-align: center;
    background-color: var(--gray-50);
    color: var(--gray-500);
  }
  
  .empty-state-subtitle {
    font-size: 0.875rem;
    margin-top: 0.5rem;
  }
  
  .teacher-table {
    width: 100%;
    border-collapse: collapse;
  }
  
  .teacher-table th {
    text-align: left;
    padding: 0.75rem 1rem;
    font-size: 0.875rem;
    background-color: var(--gray-50);
    color: var(--gray-500);
  }
  
  .teacher-table td {
    padding: 0.75rem 1rem;
    border-top: 1px solid var(--gray-200);
  }
  
  .teacher-table tr:nth-child(even) {
    background-color: var(--gray-50);
  }
  
  .teacher-editing {
    display: flex;
    align-items: center;
    gap: 0.5rem;
  }
  
  .teacher-editing input {
    flex: 1;
  }
  
  .action-buttons {
    display: flex;
    justify-content: flex-end;
    gap: 0.25rem;
  }
  
  .btn-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 2rem;
    height: 2rem;
    border-radius: 0.25rem;
    background: none;
    border: none;
    cursor: pointer;
    color: var(--gray-500);
  }
  
  .btn-icon:hover {
    background-color: var(--gray-100);
    color: var(--gray-700);
  }
  
  .btn-edit {
    color: var(--primary-color);
  }
  
  .btn-check {
    color: var(--secondary-color);
  }
  
  .btn-x {
    color: var(--danger-color);
  }
  
  /* Schedule */
  .schedule-filters {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1rem;
  }
  
  .schedule-table {
    width: 100%;
    border-collapse: collapse;
  }
  
  .schedule-table th {
    text-align: left;
    padding: 0.75rem 1rem;
    font-size: 0.875rem;
    background-color: var(--gray-50);
    color: var(--gray-500);
  }
  
  .schedule-table td {
    padding: 0.75rem 1rem;
    border-top: 1px solid var(--gray-200);
  }
  
  .schedule-table tr:nth-child(even) {
    background-color: var(--gray-50);
  }
  
  .teacher-summary {
    margin-top: 1.5rem;
    padding: 1rem;
    background-color: #eff6ff;
    border-radius: var(--border-radius);
  }
  
  .teacher-summary h3 {
    font-size: 1rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
  }
  
  .teacher-stats {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 0.5rem;
  }
  
  .teacher-stat {
    background-color: white;
    padding: 0.5rem 0.75rem;
    border-radius: 0.25rem;
    border: 1px solid var(--gray-200);
    font-size: 0.875rem;
  }
  
  .export-buttons {
    display: flex;
    justify-content: flex-end;
    gap: 1rem;
    margin-top: 1.5rem;
  }
  
  .btn-with-icon {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
  }
  
  /* Footer */
  footer {
    background-color: var(--gray-100);
    color: var(--gray-600);
    text-align: center;
    padding: 1rem 0;
    margin-top: 3rem;
    font-size: 0.875rem;
  }
  
  /* Toast Notification */
  .toast {
    position: fixed;
    bottom: 1rem;
    right: 1rem;
    padding: 0.75rem 1rem;
    border-radius: var(--border-radius);
    background-color: var(--gray-800);
    color: white;
    box-shadow: var(--shadow-md);
    opacity: 0;
    transform: translateY(1rem);
    transition: opacity 0.3s, transform 0.3s;
    max-width: 300px;
    z-index: 1000;
  }
  
  .toast.show {
    opacity: 1;
    transform: translateY(0);
  }
  
  .toast.success {
    background-color: var(--secondary-color);
  }
  
  .toast.error {
    background-color: var(--danger-color);
  }