/* Modern EEG Videos Styling */
    :root {
      --primary-blue: #007aff;
      --primary-blue-hover: #0066cc;
      --primary-blue-light: #e6f3ff;
      --secondary-gray: #f8f9fa;
      --border-light: #e9ecef;
      --text-primary: #1a1a1a;
      --text-secondary: #666;
      --text-muted: #999;
      --success-green: #10b981;
      --success-green-light: #d1fae5;
      --warning-orange: #f59e0b;
      --warning-orange-light: #fef3c7;
      --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.06);
      --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
      --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.12);
      --radius-sm: 8px;
      --radius-md: 12px;
      --radius-lg: 16px;
      --radius-xl: 24px;
      --gradient-blue: linear-gradient(135deg, #007aff 0%, #0056cc 100%);
    }

    body {
      font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
      line-height: 1.6;
      color: var(--text-primary);
      background: linear-gradient(135deg, #fafbfc 0%, #f0f4f8 100%);
      min-height: 100vh;
    }

    /* Header Section - Remove white background */
    .hero-section {
      text-align: center;
      padding: 1rem 2rem 1rem;
      margin: 1rem auto 1rem;
    }

    /* Hide mobile-only title on desktop */
    @media (min-width: 769px) {
      .mobile-only-title {
        display: none !important;
        visibility: hidden !important;
        opacity: 0 !important;
        height: 0 !important;
        margin: 0 !important;
        padding: 0 !important;
        overflow: hidden !important;
      }

      /* Desktop-only page title styling for hero section title */
      .hero-section .page-title {
        font-size: 2.5rem;
        font-weight: 600;
        text-align: center;
        margin: 1rem 0;
        color: var(--primary-color);
        letter-spacing: -0.02em;
      }
    }

    .page-subtitle {
      font-size: 1.1rem;
      color: var(--text-secondary);
      margin-bottom: 2rem;
      max-width: 600px;
      margin-left: auto;
      margin-right: auto;
      line-height: 1.7;
    }

    /* Modern Reference Card */
    .reference-card {
      display: inline-block;
      background: var(--primary-blue-light);
      border: 1px solid rgba(0, 122, 255, 0.2);
      border-radius: var(--radius-lg);
      padding: 1.25rem 1.5rem;
      margin: 0 auto 1rem;
      max-width: 700px;
      box-shadow: var(--shadow-sm);
      transition: all 0.3s cubic-bezier(0.2, 0, 0, 1);
    }

    .reference-card:hover {
      transform: translateY(-2px);
      box-shadow: var(--shadow-md);
      border-color: var(--primary-blue);
    }

    .reference-card .ref-title {
      font-weight: 600;
      color: var(--primary-blue);
      margin-bottom: 0.5rem;
      font-size: 0.9rem;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }

    .reference-card .ref-content {
      color: var(--text-primary);
      font-size: 0.95rem;
      line-height: 1.6;
      margin: 0;
    }

    .reference-card a {
      color: var(--primary-blue);
      text-decoration: none;
      font-weight: 500;
      margin-left: 0.5rem;
      transition: color 0.2s ease;
    }

    .reference-card a:hover {
      color: var(--primary-blue-hover);
    }

    /* Dark mode for reference card */
    body.dark .reference-card {
      background: rgba(0, 122, 255, 0.15);
      border-color: rgba(0, 122, 255, 0.3);
    }

    body.dark .reference-card:hover {
      background: rgba(0, 122, 255, 0.2);
      border-color: rgba(0, 122, 255, 0.4);
    }

    body.dark .reference-card .ref-title {
      color: #60a5fa;
    }

    body.dark .reference-card .ref-content {
      color: var(--text-primary);
    }

    body.dark .reference-card a {
      color: #60a5fa;
    }

    body.dark .reference-card a:hover {
      color: #93c5fd;
    }

    /* Main Container */
    #eeg-videos-container {
      max-width: 1400px;
      margin: 0 auto 4rem;
      padding: 0 2rem 4rem;
      display: grid;
      grid-template-columns: 340px 1fr;
      gap: 2rem;
      align-items: start;
    }

    /* Enhanced Video List Sidebar */
    .video-list {
      background: white;
      border-radius: var(--radius-xl);
      box-shadow: var(--shadow-md);
      border: 1px solid var(--border-light);
      position: sticky;
      top: 2rem;
      padding: 2rem;
      overflow: hidden;
    }

    .video-list-title {
      font-size: 1.4rem;
      font-weight: 700;
      margin-bottom: 1.5rem;
      color: var(--text-primary);
      text-align: center;
      padding-bottom: 1.5rem;
      border-bottom: 2px solid var(--border-light);
      position: relative;
    }

    .video-list-title::after {
      content: '';
      position: absolute;
      bottom: -2px;
      left: 50%;
      transform: translateX(-50%);
      width: 40px;
      height: 2px;
      background: var(--gradient-blue);
      border-radius: 1px;
    }

    .video-list ul {
      list-style: none;
      padding: 0;
      margin: 0;
      display: flex;
      flex-direction: column;
      gap: 0.75rem;
    }

    .video-list li {
      padding: 1rem 1.25rem;
      background: var(--secondary-gray);
      border-radius: var(--radius-md);
      cursor: pointer;
      transition: all 0.3s cubic-bezier(0.2, 0, 0, 1);
      font-weight: 500;
      font-size: 0.9rem;
      color: var(--text-secondary);
      border: 2px solid transparent;
      position: relative;
      overflow: hidden;
    }

    .video-list li::before {
      content: '';
      position: absolute;
      top: 0;
      left: 0;
      width: 4px;
      height: 100%;
      background: transparent;
      transition: background 0.3s ease;
    }

    .video-list li:hover {
      background: var(--primary-blue-light);
      color: var(--primary-blue);
      transform: translateX(4px);
      box-shadow: var(--shadow-sm);
      border-color: rgba(0, 122, 255, 0.2);
    }

    .video-list li:hover::before {
      background: var(--primary-blue);
    }

    .video-list li.active {
      background: var(--gradient-blue);
      color: white;
      font-weight: 600;
      box-shadow: var(--shadow-lg);
      transform: translateX(4px);
      border-color: var(--primary-blue);
    }

    .video-list li.active::before {
      background: rgba(255, 255, 255, 0.3);
    }

    /* Enhanced Main Content Area */
    .main-content {
      background: white;
      border-radius: var(--radius-xl);
      box-shadow: var(--shadow-md);
      border: 1px solid var(--border-light);
      overflow: hidden;
      position: relative;
    }

    .main-content::before {
      content: '';
      position: absolute;
      top: 0;
      left: 0;
      right: 0;
      height: 4px;
      background: var(--gradient-blue);
    }

    .video-section {
      padding: 2.5rem;
    }

    /* Mobile: Reduce top padding for video section */
    @media (max-width: 768px) {
      .video-section {
        padding-top: 0.5rem !important;
        padding-left: 1.5rem !important;
        padding-right: 1.5rem !important;
        padding-bottom: 1.5rem !important;
      }

      .video-wrapper {
        margin-top: 0 !important;
        padding-top: 0 !important;
      }

      .video-wrapper h3 {
        margin-top: 0 !important;
        padding-top: 0 !important;
        margin-bottom: 1rem !important;
      }
    }

    .video-wrapper h3 {
      font-size: 1.75rem;
      font-weight: 700;
      margin-bottom: 2rem;
      text-align: center;
      color: var(--text-primary);
      letter-spacing: -0.01em;
      position: relative;
      padding-bottom: 1rem;
    }

    .video-wrapper h3::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 50%;
      transform: translateX(-50%);
      width: 60px;
      height: 3px;
      background: var(--gradient-blue);
      border-radius: 2px;
    }

    .video-wrapper video {
      width: 100%;
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-lg);
      aspect-ratio: 16/9;
      background: #000;
      margin-bottom: 2rem;
      transition: transform 0.3s ease;
    }

    .video-wrapper video:hover {
      transform: scale(1.02);
    }

    /* Enhanced Navigation Buttons */
    .video-nav {
      display: flex;
      justify-content: center;
      gap: 1rem;
      margin-top: 2rem;
      flex-wrap: wrap;
      align-items: center;
    }

    .video-nav button {
      padding: 0.875rem 1.75rem;
      border: none;
      border-radius: var(--radius-lg);
      font-weight: 600;
      font-size: 0.9rem;
      cursor: pointer;
      transition: all 0.3s cubic-bezier(0.2, 0, 0, 1);
      min-width: 140px;
      position: relative;
      overflow: hidden;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 0.5rem;
    }

    .video-nav button::before {
      content: '';
      position: absolute;
      top: 0;
      left: -100%;
      width: 100%;
      height: 100%;
      background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
      transition: left 0.5s ease;
    }

    .video-nav button:hover::before {
      left: 100%;
    }

    .btn-prev,
    .btn-next {
      background: var(--gradient-blue);
      color: white;
      box-shadow: var(--shadow-md);
    }

    .btn-prev:hover,
    .btn-next:hover {
      transform: translateY(-2px);
      box-shadow: var(--shadow-lg);
    }

    .btn-skip {
      background: var(--secondary-gray);
      color: var(--text-secondary);
      border: 2px solid var(--border-light);
    }

    .btn-skip:hover {
      background: var(--warning-orange-light);
      color: var(--warning-orange);
      border-color: var(--warning-orange);
      transform: translateY(-2px);
    }

    /* Modern Progress Display - Hidden by default, only show when there's actual progress */
    #progressDisplay {
      display: none;
      background: var(--success-green-light);
      border: 2px solid var(--success-green);
      border-radius: var(--radius-lg);
      padding: 1.25rem;
      text-align: center;
      font-weight: 600;
      color: var(--success-green);
      margin-top: 2rem;
      position: relative;
      overflow: hidden;
    }

    /* Only show progress display when there's actual progress to show */
    #progressDisplay.has-progress {
      display: block;
    }

    #progressDisplay::before {
      content: '✓';
      position: absolute;
      top: 50%;
      left: 1rem;
      transform: translateY(-50%);
      font-size: 1.2rem;
      font-weight: 700;
    }

    /* Enhanced Quiz Section */
    .quiz-section {
      display: none;
      padding: 2.5rem;
      border-top: 1px solid var(--border-light);
      background: linear-gradient(135deg, #fafbfc 0%, #f8f9fa 100%);
    }

    .quiz-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-bottom: 2rem;
      padding-bottom: 1.5rem;
      border-bottom: 2px solid var(--border-light);
      position: relative;
    }

    .quiz-header::after {
      content: '';
      position: absolute;
      bottom: -2px;
      left: 0;
      width: 80px;
      height: 2px;
      background: var(--gradient-blue);
      border-radius: 1px;
    }

    .quiz-header h3 {
      font-size: 1.5rem;
      font-weight: 700;
      margin: 0;
      color: var(--text-primary);
    }

    .progress-indicator {
      background: var(--primary-blue-light);
      color: var(--primary-blue);
      padding: 0.5rem 1rem;
      border-radius: var(--radius-md);
      font-size: 0.85rem;
      font-weight: 600;
      border: 1px solid rgba(0, 122, 255, 0.2);
    }

    .quiz-question p {
      font-size: 1.15rem;
      line-height: 1.7;
      margin-bottom: 2rem;
      color: var(--text-primary);
      font-weight: 500;
    }

    .quiz-question ul {
      list-style: none;
      padding: 0;
      margin: 0;
      display: grid;
      gap: 1rem;
    }

    .quiz-question button {
      width: 100%;
      text-align: left;
      padding: 1.25rem 1.5rem;
      border: 2px solid var(--border-light);
      background: white;
      border-radius: var(--radius-lg);
      font-size: 1rem;
      color: var(--text-primary);
      cursor: pointer;
      transition: all 0.3s cubic-bezier(0.2, 0, 0, 1);
      position: relative;
      overflow: hidden;
    }

    .quiz-question button::before {
      content: '';
      position: absolute;
      top: 0;
      left: 0;
      width: 4px;
      height: 100%;
      background: transparent;
      transition: background 0.3s ease;
    }

    .quiz-question button:hover {
      background: var(--primary-blue-light);
      border-color: var(--primary-blue);
      transform: translateX(4px);
      box-shadow: var(--shadow-md);
    }

    .quiz-question button:hover::before {
      background: var(--primary-blue);
    }

    .quiz-nav {
      display: flex;
      justify-content: space-between;
      gap: 1rem;
      margin-top: 2.5rem;
      align-items: center;
    }

    .quiz-nav button {
      padding: 0.875rem 1.75rem;
      border: none;
      border-radius: var(--radius-lg);
      font-weight: 600;
      font-size: 0.9rem;
      cursor: pointer;
      transition: all 0.3s cubic-bezier(0.2, 0, 0, 1);
      min-width: 140px;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 0.5rem;
    }

    /* Enhanced Feedback Messages */
    #feedbackMessage {
      padding: 1.25rem 1.5rem;
      margin: 1.5rem 0;
      border-radius: var(--radius-lg);
      text-align: center;
      font-weight: 600;
      border: 2px solid;
      position: relative;
      overflow: hidden;
      display: none;
      /* Hidden by default */
      min-height: 0;
    }

    /* Show feedback message when it has content */
    #feedbackMessage:not(:empty) {
      display: block;
    }

    #feedbackMessage::before {
      content: '';
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 4px;
    }

    .correct-msg {
      background: var(--success-green-light);
      color: var(--success-green);
      border-color: var(--success-green);
    }

    .correct-msg::before {
      background: var(--success-green);
    }

    .incorrect-msg {
      background: #fef2f2;
      color: #dc2626;
      border-color: #fecaca;
    }

    .incorrect-msg::before {
      background: #dc2626;
    }

    /* Mobile Responsive Enhancements */
    @media (max-width: 1024px) {
      .hero-section {
        padding: 2rem 1rem 1.5rem;
      }

      #eeg-videos-container {
        grid-template-columns: 1fr;
        gap: 1.5rem;
        padding: 0 1rem 4rem;
        margin-bottom: 4rem;
      }

      .video-list {
        position: static;
        order: 2;
        padding: 1.5rem;
      }

      .main-content {
        order: 1;
      }
    }

    @media (max-width: 768px) {

      /* Show hero section on mobile but hide the page title (floating header takes over) */
      .hero-section {
        display: block !important;
        visibility: visible !important;
        opacity: 1 !important;
        padding: 1rem !important;
        margin: 0.5rem auto !important;
      }

      /* Hide the page title in hero section on mobile (floating header shows it) */
      .hero-section .page-title {
        display: none !important;
      }

      /* Show the reference card on mobile - but hide when video is selected */
      .reference-card {
        display: inline-block !important;
        visibility: visible !important;
        opacity: 1 !important;
        margin: 0.5rem auto 1rem auto !important;
        padding: 1rem !important;
        max-width: calc(100% - 2rem) !important;
        transition: opacity 0.3s ease, display 0.3s ease !important;
      }

      /* Hide reference card when video content is shown */
      .main-content.video-selected~.hero-section .reference-card,
      body:has(.main-content.video-selected) .hero-section .reference-card,
      body:has(.main-content.video-selected) #referenceCard {
        display: none !important;
        visibility: hidden !important;
        opacity: 0 !important;
        height: 0 !important;
        margin: 0 !important;
        padding: 0 !important;
        overflow: hidden !important;
      }

      #eeg-videos-container {
        padding: 0 1rem 2rem !important;
        padding-top: 0 !important;
        gap: 1rem;
        grid-template-columns: 1fr !important;
        margin-top: 0 !important;
        margin-bottom: 6rem !important;
      }

      /* Hide desktop video list on mobile */
      .video-list {
        display: none !important;
      }

      /* Show mobile dropdown */
      .mobile-video-dropdown-container {
        display: flex !important;
        flex-direction: column;
        gap: 0.75rem;
        margin-bottom: 1.5rem;
        padding: 1rem;
        background: white;
        border-radius: 12px;
        box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
      }

      .mobile-video-dropdown-container .dropdown-label {
        font-size: 0.9rem;
        font-weight: 600;
        color: var(--text-primary);
        display: flex;
        align-items: center;
        gap: 0.5rem;
      }

      .mobile-video-dropdown-container .mobile-video-dropdown {
        width: 100%;
        padding: 14px 16px;
        padding-right: 45px;
        font-size: 16px;
        /* Prevents zoom on iOS */
        border: 2px solid var(--border-light);
        border-radius: 8px;
        background-color: white;
        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='%23333' d='M6 9L1 4h10z'/%3E%3C/svg%3E");
        background-repeat: no-repeat;
        background-position: right 16px center;
        background-size: 12px;
        color: var(--text-primary);
        cursor: pointer;
        appearance: none;
        -webkit-appearance: none;
        -moz-appearance: none;
        transition: all 0.3s ease;
      }

      .mobile-video-dropdown-container .mobile-video-dropdown:focus {
        outline: none;
        border-color: var(--primary-blue);
        box-shadow: 0 0 0 3px rgba(0, 122, 255, 0.1);
      }

      /* Back to videos button */
      .back-to-videos-btn {
        display: flex;
        align-items: center;
        gap: 0.5rem;
        padding: 0.75rem 1rem;
        margin-bottom: 1rem;
        background: var(--primary-blue-light);
        border: 2px solid var(--primary-blue);
        border-radius: 8px;
        color: var(--primary-blue);
        font-weight: 600;
        font-size: 0.9rem;
        cursor: pointer;
        transition: all 0.3s ease;
        width: 100%;
        justify-content: center;
      }

      .back-to-videos-btn:hover,
      .back-to-videos-btn:active {
        background: var(--primary-blue);
        color: white;
        transform: translateY(-1px);
        box-shadow: 0 4px 12px rgba(0, 122, 255, 0.3);
      }

      /* Initially hide video content on mobile */
      .main-content {
        display: none;
        padding-top: 0 !important;
        margin-top: 0 !important;
      }

      .main-content.video-selected {
        display: block;
        padding-top: 0 !important;
        margin-top: 0 !important;
      }

      /* Remove top padding from video section on mobile */
      .main-content .video-section {
        padding-top: 0.5rem !important;
        margin-top: 0 !important;
      }

      .mobile-video-dropdown-container.hidden {
        display: none !important;
      }

      .video-section {
        padding: 0.5rem 1rem 1.5rem 1rem !important;
        margin-top: 0 !important;
      }

      .quiz-section {
        padding: 1.5rem !important;
      }

      /* Remove extra top padding from video wrapper */
      .video-wrapper {
        margin-top: 0 !important;
        padding-top: 0 !important;
      }

      .video-wrapper h3 {
        margin-top: 0 !important;
        padding-top: 0 !important;
        margin-bottom: 1rem !important;
        font-size: 1.3rem !important;
      }

      /* Remove top margin from back button */
      .back-to-videos-btn {
        margin-top: 0 !important;
        margin-bottom: 0.75rem !important;
      }

      .video-nav {
        flex-direction: row;
        gap: 0.5rem;
        justify-content: center;
        align-items: center;
      }

      .video-nav button {
        width: auto;
        min-width: auto;
        padding: 0.5rem 0.75rem;
        font-size: 0.85rem;
        flex: 0 0 auto;
      }

      /* Hide text, show only icons on mobile */
      .video-nav button .fas,
      .video-nav button i {
        margin: 0 !important;
      }

      .video-nav .btn-prev,
      .video-nav .btn-next,
      .video-nav .btn-skip {
        min-width: 44px;
        /* Touch target size */
        height: 44px;
        padding: 0;
        display: flex;
        align-items: center;
        justify-content: center;
        border-radius: 50%;
      }

      /* Hide text on mobile, show only icons */
      .video-nav .button-text {
        display: none;
      }

      /* Ensure icons are visible and properly sized */
      .video-nav button i {
        font-size: 1.2rem;
        display: inline-block !important;
        margin: 0 !important;
      }

      /* Make buttons circular on mobile for better appearance */
      .video-nav .btn-prev,
      .video-nav .btn-next {
        border-radius: 50%;
        width: 44px;
        height: 44px;
      }

      .video-nav .btn-skip {
        border-radius: 50%;
        width: 44px;
        height: 44px;
      }

      /* Desktop: show text */
      @media (min-width: 769px) {
        .video-nav .button-text {
          display: inline;
        }

        .video-nav button {
          min-width: 140px;
          border-radius: var(--radius-lg);
          width: auto;
          height: auto;
          padding: 0.875rem 1.75rem;
        }

        .video-nav button i {
          font-size: 0.9rem;
        }
      }

      .quiz-nav {
        flex-direction: row;
        gap: 0.5rem;
        justify-content: center;
        align-items: center;
      }

      .quiz-nav button {
        width: auto !important;
        min-width: 44px !important;
        height: 44px !important;
        padding: 0 !important;
        border-radius: 50% !important;
        display: flex !important;
        align-items: center !important;
        justify-content: center !important;
        font-size: 0.85rem !important;
      }

      /* Hide text, show only icons on mobile quiz nav */
      .quiz-nav .button-text,
      .quiz-nav button span:not(.fas):not(.fa):not(i) {
        display: none !important;
      }

      .quiz-nav button i {
        font-size: 1.1rem !important;
        margin: 0 !important;
      }

      /* Shrink quiz answer buttons on mobile */
      .quiz-question button {
        padding: 0.75rem 1rem !important;
        font-size: 0.9rem !important;
        min-height: 44px !important;
      }

      /* Ensure reference card is hidden when video is selected */
      body:has(.main-content.video-selected) #referenceCard,
      body:has(.main-content.video-selected) .reference-card {
        display: none !important;
        visibility: hidden !important;
        opacity: 0 !important;
        height: 0 !important;
        margin: 0 !important;
        padding: 0 !important;
        overflow: hidden !important;
      }
    }

    /* Dark mode support */
    body.dark {
      --secondary-gray: #1a1a1a;
      --border-light: #333;
      --text-primary: #ffffff;
      --text-secondary: #999;
      --text-muted: #666;
    }

    body.dark {
      background: linear-gradient(135deg, #0a0a0a 0%, #1a1a1a 100%);
      color: var(--text-primary);
    }

    body.dark .hero-section,
    body.dark .video-list,
    body.dark .main-content,
    body.dark .mobile-video-dropdown-container {
      background: #1a1a1a;
      border-color: var(--border-light);
    }

    body.dark .video-list li {
      background: var(--secondary-gray);
      color: var(--text-secondary);
    }

    body.dark .video-list li:hover {
      background: #1e3a8a;
      color: #60a5fa;
    }

    body.dark .mobile-video-dropdown-container .mobile-video-dropdown {
      background-color: #1a1a1a;
      border-color: var(--border-light);
      color: var(--text-primary);
      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='%23fff' d='M6 9L1 4h10z'/%3E%3C/svg%3E");
    }

    body.dark .mobile-video-dropdown-container .mobile-video-dropdown:focus {
      border-color: var(--primary-blue);
      box-shadow: 0 0 0 3px rgba(0, 122, 255, 0.2);
    }

    body.dark .mobile-video-dropdown-container .dropdown-label {
      color: var(--text-primary);
    }

    body.dark .back-to-videos-btn {
      background: rgba(0, 122, 255, 0.2);
      border-color: var(--primary-blue);
      color: #60a5fa;
    }

    body.dark .back-to-videos-btn:hover,
    body.dark .back-to-videos-btn:active {
      background: var(--primary-blue);
      color: white;
    }

    body.dark .quiz-question button {
      background: var(--secondary-gray);
      border-color: var(--border-light);
      color: var(--text-primary);
    }

    body.dark .quiz-question button:hover {
      background: #1e3a8a;
      border-color: var(--primary-blue);
    }

    body.dark .quiz-section {
      background: linear-gradient(135deg, #0f0f0f 0%, #1a1a1a 100%);
    }

    /* Desktop: Hide mobile dropdown */
    @media (min-width: 769px) {
      .mobile-video-dropdown-container {
        display: none !important;
      }

      .back-to-videos-btn {
        display: none !important;
      }

      .video-list {
        display: block !important;
      }

      .main-content {
        display: block !important;
      }
    }

    /* Loading and Animation Enhancements */
    @keyframes slideInUp {
      from {
        opacity: 0;
        transform: translateY(30px);
      }

      to {
        opacity: 1;
        transform: translateY(0);
      }
    }

    @keyframes fadeIn {
      from {
        opacity: 0;
      }

      to {
        opacity: 1;
      }
    }

    .video-list li,
    .main-content,
    .reference-card {
      animation: slideInUp 0.6s ease forwards;
    }

    .video-list li:nth-child(odd) {
      animation-delay: 0.1s;
    }

    .video-list li:nth-child(even) {
      animation-delay: 0.2s;
    }

    /* Quiz completion belongs to this page. It previously inherited these
       rules from the globally loaded Fundamentals stylesheet. */
    .quiz-results {
      background: rgba(0, 136, 255, 0.05);
      padding: 1.5rem;
      border-radius: 12px;
      text-align: center;
    }

    .quiz-results .success {
      color: #28a745;
      font-weight: 600;
    }

    .quiz-results .warning {
      color: #ffc107;
      font-weight: 600;
    }

    .quiz-results .error {
      color: #dc3545;
      font-weight: 600;
    }