:root {
      --primary: #2563eb;
      --primary-hover: #1d4ed8;
      --secondary: #1e293b;
      --accent: #f59e0b;
      --success: #10b981;
      --warning: #f59e0b;
      --error: #ef4444;
      --light: #f8fafc;
      --lighter: #ffffff;
      --dark: #0f172a;
      --text: #334155;
      --text-light: #64748b;
      --text-muted: #94a3b8;
      --border: #e2e8f0;
      --border-light: #f1f5f9;
      --shadow: rgba(15, 23, 42, 0.1);
      --shadow-lg: rgba(15, 23, 42, 0.15);
      --gradient: linear-gradient(to right, #24243e, #302b63, #0f0c29);
      --gradient-subtle: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
      --border-radius: 12px;
      --border-radius-lg: 16px;
      --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
      --spacing-xs: 0.25rem;
      --spacing-sm: 0.5rem;
      --spacing-md: 1rem;
      --spacing-lg: 1.5rem;
      --spacing-xl: 2rem;
      --spacing-2xl: 3rem;
  }

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

  html {
      scroll-behavior: smooth;
  }

  body {
      font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
      background: var(--gradient);
      color: var(--text);
      line-height: 1.7;
      font-size: 16px;
      min-height: 100vh;
      padding: var(--spacing-lg);
      overflow-x: hidden;
  }

  .container {
      max-width: 1000px;
      margin: 0 auto;
      background: var(--lighter);
      border-radius: var(--border-radius-lg);
      box-shadow: 0 25px 50px -12px var(--shadow-lg);
      overflow: hidden;
      position: relative;
  }

  /* Navigation */
  .navigation {
      padding: var(--spacing-lg) var(--spacing-xl);
      background: var(--gradient-subtle);
      border-bottom: 1px solid var(--border);
  }

  .btn {
      display: inline-flex;
      align-items: center;
      gap: var(--spacing-sm);
      padding: var(--spacing-sm) var(--spacing-lg);
      border-radius: var(--spacing-sm);
      text-decoration: none;
      font-weight: 600;
      font-size: 0.95rem;
      transition: var(--transition);
      border: none;
      cursor: pointer;
      position: relative;
      overflow: hidden;
  }

  .btn-home {
      background: var(--lighter);
      color: var(--text);
      border: 2px solid var(--border);
      box-shadow: 0 2px 4px var(--shadow);
  }

  .btn-home:hover {
      background: var(--light);
      transform: translateY(-2px);
      box-shadow: 0 8px 25px var(--shadow);
      border-color: var(--primary);
  }

  .btn-home i {
      font-size: 1rem;
  }

  /* Header */
  .checklist-header {
      background: var(--gradient);
      color: white;
      padding: var(--spacing-2xl) var(--spacing-xl);
      text-align: center;
      position: relative;
      overflow: hidden;
  }

  .checklist-header::before {
      content: '';
      position: absolute;
      top: 0;
      left: 0;
      right: 0;
      bottom: 0;
      background: radial-gradient(circle at 30% 40%, rgba(255, 255, 255, 0.1) 0%, transparent 50%);
      pointer-events: none;
  }

  .checklist-header h1 {
      font-size: 2.75rem;
      font-weight: 800;
      margin-bottom: var(--spacing-md);
      letter-spacing: -0.025em;
      position: relative;
      z-index: 1;
  }

  .header-description {
      font-size: 1.2rem;
      opacity: 0.9;
      font-weight: 300;
      max-width: 600px;
      margin: 0 auto;
      position: relative;
      z-index: 1;
  }

  /* Progress Overview */
  .progress-overview {
      padding: var(--spacing-2xl) var(--spacing-xl);
      background: var(--light);
      border-bottom: 1px solid var(--border);
  }

  .progress-overview h2 {
      font-size: 1.5rem;
      font-weight: 700;
      color: var(--secondary);
      margin-bottom: var(--spacing-lg);
      text-align: center;
  }

  .progress-container {
      max-width: 600px;
      margin: 0 auto;
  }

  .progress-bar {
      width: 100%;
      height: 24px;
      background: var(--border-light);
      border-radius: 12px;
      overflow: hidden;
      position: relative;
      margin-bottom: var(--spacing-lg);
      box-shadow: inset 0 2px 4px var(--shadow);
  }

  .progress-fill {
      height: 100%;
      background: var(--gradient);
      width: 0%;
      transition: width 0.6s cubic-bezier(0.4, 0, 0.2, 1);
      position: relative;
      border-radius: 12px;
  }

  .progress-shimmer {
      position: absolute;
      top: 0;
      left: 0;
      right: 0;
      bottom: 0;
      background: linear-gradient(90deg, transparent 0%, rgba(255, 255, 255, 0.4) 50%, transparent 100%);
      transform: translateX(-100%);
      animation: shimmer 2s infinite;
  }

  @keyframes shimmer {
      0% { transform: translateX(-100%); }
      100% { transform: translateX(200%); }
  }

  .progress-stats {
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-size: 0.95rem;
  }

  #progress-text {
      font-weight: 600;
      color: var(--text);
  }

  .estimated-time {
      color: var(--text-light);
      font-weight: 500;
  }

  /* Checklist Container */
  .checklist-container {
      padding: var(--spacing-xl);
      background: var(--lighter);
  }

  /* Sections */
  .checklist-section {
      margin-bottom: var(--spacing-xl);
      border: 1px solid var(--border);
      border-radius: var(--border-radius);
      overflow: hidden;
      background: var(--lighter);
      transition: var(--transition);
  }

  .checklist-section:hover {
      box-shadow: 0 8px 25px var(--shadow);
      border-color: var(--primary);
  }

  .section-header {
      padding: var(--spacing-lg) var(--spacing-xl);
      background: var(--gradient-subtle);
      border-bottom: 1px solid var(--border);
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
      transition: var(--transition);
      position: relative;
  }

  .section-header:hover {
      background: linear-gradient(135deg, #e2e8f0 0%, #cbd5e1 100%);
  }

  .section-header:focus {
      outline: 2px solid var(--primary);
      outline-offset: 2px;
  }

  .section-title {
      display: flex;
      align-items: center;
      gap: var(--spacing-md);
  }

  .section-icon {
      font-size: 1.2rem;
      color: var(--primary);
      width: 24px;
      text-align: center;
  }

  .section-title h3 {
      font-size: 1.2rem;
      font-weight: 700;
      color: var(--secondary);
      margin: 0;
  }

  .section-meta {
      display: flex;
      align-items: center;
      gap: var(--spacing-md);
  }

  .section-progress {
      background: var(--primary);
      color: white;
      padding: var(--spacing-xs) var(--spacing-md);
      border-radius: 20px;
      font-size: 0.85rem;
      font-weight: 600;
      min-width: 60px;
      text-align: center;
      box-shadow: 0 2px 4px rgba(37, 99, 235, 0.3);
  }

  .expand-icon {
      font-size: 0.9rem;
      color: var(--text-light);
      transition: var(--transition);
  }

  .section-header[aria-expanded="true"] .expand-icon {
      transform: rotate(180deg);
  }

  .section-content {
      padding: 0;
      background: var(--lighter);
      display: none;
      border-top: 1px solid var(--border-light);
  }

  .section-content.active {
      display: block;
      animation: slideDown 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  }

  @keyframes slideDown {
      from {
          opacity: 0;
          transform: translateY(-20px);
          max-height: 0;
      }
      to {
          opacity: 1;
          transform: translateY(0);
          max-height: 1000px;
      }
  }

  /* Checklist Items */
  .checklist-item {
      display: flex;
      align-items: flex-start;
      padding: var(--spacing-lg) var(--spacing-xl);
      border-bottom: 1px solid var(--border-light);
      transition: var(--transition);
      position: relative;
      gap: var(--spacing-md);
  }

  .checklist-item:last-of-type {
      border-bottom: none;
  }

  .checklist-item:hover {
      background: rgba(37, 99, 235, 0.02);
      padding-left: calc(var(--spacing-xl) + var(--spacing-sm));
  }

  .checklist-item::before {
      content: '';
      position: absolute;
      left: 0;
      top: 0;
      bottom: 0;
      width: 4px;
      background: transparent;
      transition: var(--transition);
  }

  .checklist-item:hover::before {
      background: var(--primary);
  }

  /* Custom Checkbox */
  .checklist-item input[type="checkbox"] {
      width: 22px;
      height: 22px;
      cursor: pointer;
      position: relative;
      appearance: none;
      border: 2px solid var(--border);
      border-radius: var(--spacing-sm);
      background: var(--lighter);
      transition: var(--transition);
      flex-shrink: 0;
      margin-top: 2px;
  }

  .checklist-item input[type="checkbox"]:hover {
      border-color: var(--primary);
      box-shadow: 0 0 0 4px rgba(37, 99, 235, 0.1);
      transform: scale(1.05);
  }

  .checklist-item input[type="checkbox"]:focus {
      outline: 2px solid var(--primary);
      outline-offset: 2px;
  }

  .checklist-item input[type="checkbox"]:checked {
      background: var(--primary);
      border-color: var(--primary);
      transform: scale(1.02);
  }

  .checklist-item input[type="checkbox"]:checked::after {
      content: '✓';
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      color: white;
      font-weight: bold;
      font-size: 14px;
      animation: checkmark 0.2s ease;
  }

  @keyframes checkmark {
      0% {
          opacity: 0;
          transform: translate(-50%, -50%) scale(0);
      }
      100% {
          opacity: 1;
          transform: translate(-50%, -50%) scale(1);
      }
  }

  .checklist-item label {
      flex: 1;
      cursor: pointer;
      font-weight: 500;
      color: var(--text);
      transition: var(--transition);
      line-height: 1.6;
      padding-top: 2px;
  }

  .checklist-item input[type="checkbox"]:checked + label {
      color: var(--success);
      text-decoration: line-through;
      opacity: 0.8;
  }

  .date-completed {
      font-size: 0.85rem;
      color: var(--success);
      font-weight: 600;
      padding: var(--spacing-xs) var(--spacing-sm);
      background: #f0fdf4;
      border-radius: var(--spacing-sm);
      border: 1px solid #bbf7d0;
      white-space: nowrap;
      margin-left: var(--spacing-md);
  }

  /* Notes Section */
  .section-content h4 {
      margin: var(--spacing-xl) var(--spacing-xl) var(--spacing-md);
      color: var(--text);
      font-weight: 600;
      font-size: 1rem;
  }

  .notes-area {
      margin: 0 var(--spacing-xl) var(--spacing-xl);
      width: calc(100% - var(--spacing-2xl) * 2);
      min-height: 120px;
      padding: var(--spacing-lg);
      border: 2px solid var(--border);
      border-radius: var(--border-radius);
      font-family: inherit;
      font-size: 0.95rem;
      resize: vertical;
      transition: var(--transition);
      background: var(--lighter);
      line-height: 1.6;
  }

  .notes-area:focus {
      outline: none;
      border-color: var(--primary);
      box-shadow: 0 0 0 4px rgba(37, 99, 235, 0.1);
      background: #fefeff;
  }

  .notes-area::placeholder {
      color: var(--text-muted);
      font-style: italic;
  }

  /* Action Bar */
  .action-bar {
      padding: var(--spacing-2xl);
      background: var(--light);
      border-top: 1px solid var(--border);
  }

  .button-group {
      display: flex;
      gap: var(--spacing-md);
      justify-content: center;
      flex-wrap: wrap;
  }

  .btn-save {
      background: var(--success);
      color: white;
      box-shadow: 0 4px 14px rgba(16, 185, 129, 0.3);
  }

  .btn-save:hover {
      background: #059669;
      transform: translateY(-2px);
      box-shadow: 0 8px 25px rgba(16, 185, 129, 0.4);
  }

  .btn-export {
      background: var(--primary);
      color: white;
      box-shadow: 0 4px 14px rgba(37, 99, 235, 0.3);
  }

  .btn-export:hover {
      background: var(--primary-hover);
      transform: translateY(-2px);
      box-shadow: 0 8px 25px rgba(37, 99, 235, 0.4);
  }

  .btn-reset {
      background: var(--error);
      color: white;
      box-shadow: 0 4px 14px rgba(239, 68, 68, 0.3);
  }

  .btn-reset:hover {
      background: #dc2626;
      transform: translateY(-2px);
      box-shadow: 0 8px 25px rgba(239, 68, 68, 0.4);
  }

  .action-bar .btn {
      padding: var(--spacing-md) var(--spacing-xl);
      font-size: 1rem;
      min-width: 160px;
  }

  /* Completion States */
  .checklist-item.completed {
      background: rgba(16, 185, 129, 0.02);
  }

  .checklist-section.completed .section-header {
      background: linear-gradient(135deg, #f0fdf4 0%, #dcfce7 100%);
  }

  .checklist-section.completed .section-progress {
      background: var(--success);
  }

  /* Loading States */
  .btn.loading {
      pointer-events: none;
      opacity: 0.8;
  }

  .btn.loading::after {
      content: '';
      width: 16px;
      height: 16px;
      border: 2px solid transparent;
      border-top: 2px solid currentColor;
      border-radius: 50%;
      animation: spin 1s linear infinite;
      margin-left: var(--spacing-sm);
  }

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

  /* Responsive Design */
  @media (max-width: 1024px) {
      body {
          padding: var(--spacing-md);
      }

      .checklist-header h1 {
          font-size: 2.25rem;
      }

      .header-description {
          font-size: 1.1rem;
      }
  }

  @media (max-width: 768px) {
      body {
          padding: var(--spacing-sm);
      }

      .container {
          border-radius: var(--border-radius);
      }

      .navigation,
      .checklist-header,
      .progress-overview,
      .checklist-container,
      .action-bar {
          padding-left: var(--spacing-lg);
          padding-right: var(--spacing-lg);
      }

      .checklist-header {
          padding-top: var(--spacing-xl);
          padding-bottom: var(--spacing-xl);
      }

      .checklist-header h1 {
          font-size: 2rem;
      }

      .header-description {
          font-size: 1rem;
      }

      .section-header {
          padding: var(--spacing-md) var(--spacing-lg);
      }

      .section-title h3 {
          font-size: 1.1rem;
      }

      .checklist-item {
          padding: var(--spacing-md) var(--spacing-lg);
          flex-direction: row;
          align-items: flex-start;
      }

      .notes-area {
          margin: 0 var(--spacing-lg) var(--spacing-lg);
          width: calc(100% - var(--spacing-xl));
      }

      .section-content h4 {
          margin-left: var(--spacing-lg);
          margin-right: var(--spacing-lg);
      }

      .button-group {
          flex-direction: column;
      }

      .action-bar .btn {
          width: 100%;
          min-width: auto;
          justify-content: center;
      }

      .progress-stats {
          flex-direction: column;
          gap: var(--spacing-sm);
          text-align: center;
      }
  }

  @media (max-width: 480px) {
      .checklist-header h1 {
          font-size: 1.75rem;
      }

      .header-description {
          font-size: 0.95rem;
      }

      .section-title {
          gap: var(--spacing-sm);
      }

      .section-title h3 {
          font-size: 1rem;
      }

      .checklist-item {
          padding: var(--spacing-md);
      }

      .checklist-item label {
          font-size: 0.95rem;
      }

      .date-completed {
          display: block;
          margin-left: 0;
          margin-top: var(--spacing-sm);
          width: fit-content;
      }
  }

  /* Accessibility Improvements */
  @media (prefers-reduced-motion: reduce) {
      * {
          animation-duration: 0.01ms !important;
          animation-iteration-count: 1 !important;
          transition-duration: 0.01ms !important;
          scroll-behavior: auto !important;
      }
  }

  /* High contrast mode support */
  @media (prefers-contrast: high) {
      :root {
          --border: #000000;
          --shadow: rgba(0, 0, 0, 0.3);
          --text-light: var(--text);
      }

      .checklist-item input[type="checkbox"] {
          border-width: 3px;
      }

      .section-header {
          border-width: 2px;
      }
  }

  /* Focus visible for better keyboard navigation */
  .btn:focus-visible,
  .section-header:focus-visible,
  input[type="checkbox"]:focus-visible,
  .notes-area:focus-visible {
      outline: 3px solid var(--primary);
      outline-offset: 2px;
  }
/* Legacy compatibility for old HTML structure */
.section {
    margin-bottom: var(--spacing-xl);
    border: 1px solid var(--border);
    border-radius: var(--border-radius);
    overflow: hidden;
    background: var(--lighter);
    transition: var(--transition);
}

.section:hover {
    box-shadow: 0 8px 25px var(--shadow);
    border-color: var(--primary);
}

.section .section-header {
    padding: var(--spacing-lg) var(--spacing-xl);
    background: var(--gradient-subtle);
    border-bottom: 1px solid var(--border);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: var(--transition);
    position: relative;
}

.section .section-header:hover {
    background: linear-gradient(135deg, #e2e8f0 0%, #cbd5e1 100%);
}

.section .section-header span:first-child {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--secondary);
}

.section .section-content {
    padding: 0;
    background: var(--lighter);
    display: none;
    border-top: 1px solid var(--border-light);
}

.section .section-content.active {
    display: block !important;
    animation: slideDown 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Force display for debugging */
.section-content[style*="display: block"] {
    display: block !important;
}