/* Course Header with UP accent */
    .course-header {
        background: var(--bg-white);
        margin: -32px -32px 32px -32px;
        padding: 32px;
        border-bottom: 1px solid var(--border);
        position: relative;
    }

    .course-header::after {
        content: '';
        position: absolute;
        bottom: 0;
        left: 0;
        right: 0;
        height: 3px;
        background: linear-gradient(90deg, var(--up-green) 0%, var(--up-maroon) 50%, var(--up-gold) 100%);
    }

    .course-header-top {
        display: flex;
        align-items: flex-start;
        justify-content: space-between;
        margin-bottom: 16px;
    }

    .course-info h1 {
        font-size: 28px;
        font-weight: 700;
        color: var(--text-primary);
        margin-bottom: 4px;
    }

    .course-info .course-code {
        font-size: 14px;
        font-weight: 600;
        color: var(--up-green);
        text-transform: uppercase;
        letter-spacing: 0.5px;
    }

    .course-info .course-description {
        font-size: 15px;
        color: var(--text-secondary);
        margin-top: 8px;
        max-width: 600px;
    }

    /* Tabs */
    .course-tabs {
        display: flex;
        gap: 4px;
        border-bottom: 1px solid var(--border);
        margin-bottom: 32px;
    }

    .course-tab {
        display: flex;
        align-items: center;
        gap: 8px;
        padding: 14px 24px;
        font-size: 14px;
        font-weight: 500;
        color: var(--text-secondary);
        text-decoration: none;
        border-bottom: 2px solid transparent;
        margin-bottom: -1px;
        transition: all var(--transition);
        cursor: pointer;
        background: none;
        border-top: none;
        border-left: none;
        border-right: none;
    }

    .course-tab:hover {
        color: var(--text-primary);
    }

    .course-tab.active {
        color: var(--primary);
        border-bottom-color: var(--primary);
    }

    .course-tab .tab-icon {
        font-size: 16px;
    }

    .course-tab .tab-count {
        background: var(--bg-main);
        padding: 2px 8px;
        border-radius: 10px;
        font-size: 12px;
        font-weight: 600;
    }

    .course-tab.active .tab-count {
        background: var(--primary-light);
        color: var(--primary);
    }

    /* Tab Content */
    .tab-content {
        display: none;
    }

    .tab-content.active {
        display: block;
    }

    /* Module Timeline */
    .modules-timeline {
        max-width: 800px;
    }

    .module-category {
        margin-bottom: 32px;
    }

    .category-header {
        display: flex;
        align-items: center;
        gap: 12px;
        margin-bottom: 16px;
        padding-bottom: 8px;
        border-bottom: 1px solid var(--border-light);
    }

    .category-title {
        font-size: 14px;
        font-weight: 600;
        text-transform: uppercase;
        letter-spacing: 0.5px;
        color: var(--text-muted);
    }

    .category-count {
        font-size: 12px;
        color: var(--text-muted);
        background: var(--bg-main);
        padding: 2px 8px;
        border-radius: 10px;
    }

    .module-list {
        display: flex;
        flex-direction: column;
        gap: 8px;
    }

    .module-item {
        display: flex;
        align-items: center;
        gap: 16px;
        padding: 16px 20px;
        background: var(--bg-white);
        border: 1px solid var(--border);
        border-radius: var(--radius);
        text-decoration: none;
        transition: all var(--transition);
    }

    .module-item:hover {
        border-color: var(--primary);
        box-shadow: var(--shadow);
        transform: translateX(4px);
    }

    .module-number {
        width: 40px;
        height: 40px;
        background: var(--primary-light);
        color: var(--primary);
        border-radius: 50%;
        display: flex;
        align-items: center;
        justify-content: center;
        font-weight: 600;
        font-size: 14px;
        flex-shrink: 0;
    }

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

    .module-title {
        font-size: 15px;
        font-weight: 500;
        color: var(--text-primary);
        margin-bottom: 2px;
    }

    .module-meta {
        font-size: 13px;
        color: var(--text-muted);
    }

    .module-status {
        display: flex;
        align-items: center;
        gap: 8px;
    }

    .module-arrow {
        color: var(--text-muted);
        font-size: 18px;
    }

    .module-item:hover .module-arrow {
        color: var(--primary);
    }

    /* Projects Section */
    .projects-grid {
        display: grid;
        grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
        gap: 20px;
    }

    .project-card {
        background: var(--bg-white);
        border: 1px solid var(--border);
        border-radius: var(--radius-lg);
        overflow: hidden;
        transition: all var(--transition);
    }

    .project-card:hover {
        box-shadow: var(--shadow-md);
        border-color: var(--primary);
    }

    .project-card-header {
        padding: 20px 24px;
        border-bottom: 1px solid var(--border-light);
    }

    .project-title {
        font-size: 18px;
        font-weight: 600;
        color: var(--text-primary);
        margin-bottom: 6px;
    }

    .project-description {
        font-size: 14px;
        color: var(--text-secondary);
    }

    .project-card-body {
        padding: 20px 24px;
    }

    .project-stages {
        display: flex;
        flex-direction: column;
        gap: 10px;
    }

    .stage-item {
        display: flex;
        align-items: center;
        gap: 12px;
        font-size: 14px;
    }

    .stage-number {
        width: 24px;
        height: 24px;
        background: var(--bg-main);
        border-radius: 50%;
        display: flex;
        align-items: center;
        justify-content: center;
        font-size: 12px;
        font-weight: 600;
        color: var(--text-muted);
    }

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

    .project-card-footer {
        padding: 16px 24px;
        background: var(--bg-main);
        border-top: 1px solid var(--border-light);
    }

    .project-action {
        display: flex;
        align-items: center;
        justify-content: space-between;
    }

    .project-action a {
        display: inline-flex;
        align-items: center;
        gap: 8px;
        color: var(--primary);
        font-weight: 500;
        font-size: 14px;
        text-decoration: none;
    }

    .project-action a:hover {
        text-decoration: underline;
    }

    /* Empty State */
    .empty-state {
        text-align: center;
        padding: 60px 20px;
        color: var(--text-muted);
    }

    .empty-state-icon {
        font-size: 48px;
        margin-bottom: 16px;
    }

    .empty-state h3 {
        font-size: 18px;
        font-weight: 600;
        color: var(--text-secondary);
        margin-bottom: 8px;
    }

    .empty-state p {
        font-size: 14px;
    }

    /* Loading State */
    .loading-state {
        display: flex;
        flex-direction: column;
        align-items: center;
        padding: 60px 20px;
        color: var(--text-muted);
    }

    .spinner {
        width: 32px;
        height: 32px;
        border: 3px solid var(--border);
        border-top-color: var(--primary);
        border-radius: 50%;
        animation: spin 0.8s linear infinite;
        margin-bottom: 12px;
    }

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

    /* Resources Grid */
    .resources-container {
        min-height: 200px;
    }

    .resources-grid {
        display: grid;
        grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
        gap: 24px;
    }

    /* Video Facade Pattern - Lightweight thumbnails, load iframe on click */
    .video-facade {
        position: relative;
        background: #000;
        border-radius: var(--radius-lg);
        overflow: hidden;
        cursor: pointer;
        aspect-ratio: 16 / 9;
    }

    .video-facade img {
        width: 100%;
        height: 100%;
        object-fit: cover;
        transition: opacity 0.2s;
    }

    .video-facade:hover img {
        opacity: 0.85;
    }

    .video-facade .play-btn {
        position: absolute;
        top: 50%;
        left: 50%;
        transform: translate(-50%, -50%);
        width: 68px;
        height: 48px;
        background: rgba(255, 0, 0, 0.9);
        border: none;
        border-radius: 12px;
        cursor: pointer;
        transition: all 0.2s;
        display: flex;
        align-items: center;
        justify-content: center;
    }

    .video-facade:hover .play-btn {
        background: #ff0000;
        transform: translate(-50%, -50%) scale(1.1);
    }

    .video-facade .play-btn::before {
        content: '';
        border-style: solid;
        border-width: 10px 0 10px 18px;
        border-color: transparent transparent transparent #fff;
        margin-left: 4px;
    }

    /* Video loaded state */
    .video-facade.loaded {
        cursor: default;
    }

    .video-facade.loaded img,
    .video-facade.loaded .play-btn {
        display: none;
    }

    .video-facade iframe {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        border: none;
    }

    /* Resource Card */
    .resource-card {
        background: var(--bg-white);
        border: 1px solid var(--border);
        border-radius: var(--radius-lg);
        overflow: hidden;
        transition: all var(--transition);
    }

    .resource-card:hover {
        box-shadow: var(--shadow-md);
        border-color: var(--primary);
    }

    .resource-card-body {
        padding: 16px 20px;
    }

    .resource-title {
        font-size: 16px;
        font-weight: 600;
        color: var(--text-primary);
        margin-bottom: 4px;
    }

    .resource-description {
        font-size: 14px;
        color: var(--text-secondary);
        display: -webkit-box;
        -webkit-line-clamp: 2;
        -webkit-box-orient: vertical;
        overflow: hidden;
    }

    /* Link/PDF Resources */
    .resource-link {
        display: flex;
        align-items: center;
        gap: 16px;
        padding: 20px;
        background: var(--bg-white);
        border: 1px solid var(--border);
        border-radius: var(--radius-lg);
        text-decoration: none;
        transition: all var(--transition);
    }

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

    .resource-link-icon {
        width: 48px;
        height: 48px;
        background: var(--primary-light);
        color: var(--primary);
        border-radius: 12px;
        display: flex;
        align-items: center;
        justify-content: center;
        font-size: 24px;
        flex-shrink: 0;
    }

    .resource-link-icon.pdf {
        background: #fef3f2;
        color: #dc2626;
    }

    .resource-link-info {
        flex: 1;
        min-width: 0;
    }

    .resource-link-arrow {
        color: var(--text-muted);
        font-size: 20px;
    }

    .resource-link:hover .resource-link-arrow {
        color: var(--primary);
    }

    /* Exam Section Styles */
    .exam-container {
        max-width: 800px;
    }

    .exam-header {
        display: flex;
        align-items: center;
        gap: 20px;
        margin-bottom: 32px;
        padding: 24px;
        background: linear-gradient(135deg, #f0f9ff 0%, #e0f2fe 100%);
        border: 2px solid #0ea5e9;
        border-radius: var(--radius-lg);
    }

    .exam-icon {
        font-size: 48px;
    }

    .exam-info h2 {
        font-size: 24px;
        font-weight: 700;
        color: var(--text-primary);
        margin-bottom: 4px;
    }

    .exam-subtitle {
        font-size: 15px;
        color: var(--text-secondary);
    }

    .exam-details {
        display: grid;
        grid-template-columns: repeat(3, 1fr);
        gap: 16px;
        margin-bottom: 32px;
    }

    .exam-detail-card {
        display: flex;
        align-items: center;
        gap: 12px;
        padding: 16px;
        background: var(--bg-white);
        border: 1px solid var(--border);
        border-radius: var(--radius);
    }

    .detail-icon {
        font-size: 28px;
    }

    .detail-content h4 {
        font-size: 12px;
        font-weight: 600;
        text-transform: uppercase;
        letter-spacing: 0.5px;
        color: var(--text-muted);
        margin-bottom: 2px;
    }

    .detail-content p {
        font-size: 15px;
        font-weight: 600;
        color: var(--text-primary);
    }

    .exam-structure {
        margin-bottom: 32px;
    }

    .exam-structure h3,
    .exam-instructions h3 {
        font-size: 16px;
        font-weight: 600;
        color: var(--text-primary);
        margin-bottom: 16px;
        padding-bottom: 8px;
        border-bottom: 1px solid var(--border);
    }

    .structure-grid {
        display: grid;
        grid-template-columns: repeat(2, 1fr);
        gap: 12px;
    }

    .structure-item {
        display: flex;
        align-items: center;
        gap: 12px;
        padding: 14px 16px;
        background: var(--bg-white);
        border: 1px solid var(--border);
        border-radius: var(--radius);
    }

    .structure-item.bonus {
        background: linear-gradient(135deg, #fefce8 0%, #fef9c3 100%);
        border-color: #eab308;
    }

    .part-label {
        font-size: 11px;
        font-weight: 700;
        text-transform: uppercase;
        color: var(--primary);
        background: var(--primary-light);
        padding: 4px 8px;
        border-radius: 4px;
    }

    .structure-item.bonus .part-label {
        color: #a16207;
        background: #fef08a;
    }

    .part-title {
        flex: 1;
        font-size: 14px;
        color: var(--text-secondary);
    }

    .part-points {
        font-size: 13px;
        font-weight: 600;
        color: var(--text-primary);
    }

    .exam-instructions {
        margin-bottom: 32px;
    }

    .exam-instructions ul {
        list-style: none;
        padding: 0;
    }

    .exam-instructions li {
        position: relative;
        padding: 10px 0 10px 28px;
        font-size: 14px;
        color: var(--text-secondary);
        border-bottom: 1px solid var(--border-light);
    }

    .exam-instructions li:last-child {
        border-bottom: none;
    }

    .exam-instructions li::before {
        content: '✓';
        position: absolute;
        left: 0;
        color: var(--success);
        font-weight: bold;
    }

    .exam-instructions code {
        background: var(--bg-main);
        padding: 2px 6px;
        border-radius: 4px;
        font-size: 13px;
    }

    .exam-download {
        text-align: center;
        padding: 32px;
        background: var(--bg-main);
        border-radius: var(--radius-lg);
    }

    .exam-buttons {
        display: flex;
        gap: 16px;
        justify-content: center;
        flex-wrap: wrap;
    }

    .btn-lg {
        padding: 16px 32px;
        font-size: 16px;
    }

    .btn-lg span {
        margin-right: 8px;
    }

    .download-note {
        margin-top: 12px;
        font-size: 13px;
        color: var(--text-muted);
    }

    @media (max-width: 768px) {
        .exam-details {
            grid-template-columns: 1fr;
        }

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

    /* Exam Sub-tabs */
    .exam-subtabs {
        display: flex;
        gap: 4px;
        margin-bottom: 24px;
        border-bottom: 2px solid var(--border);
    }

    .exam-subtab {
        padding: 12px 24px;
        border: none;
        background: transparent;
        color: var(--text-secondary);
        font-weight: 500;
        font-size: 14px;
        cursor: pointer;
        border-bottom: 3px solid transparent;
        margin-bottom: -2px;
        transition: all 0.2s;
    }

    .exam-subtab:hover {
        color: var(--text-primary);
        background: var(--bg-main);
    }

    .exam-subtab.active {
        color: var(--primary);
        border-bottom-color: var(--primary);
        background: transparent;
    }

    .exam-subtab.answer-key-tab {
        color: #dc2626;
    }

    .exam-subtab.answer-key-tab:hover {
        background: #fef2f2;
    }

    .exam-subtab.answer-key-tab.active {
        border-bottom-color: #dc2626;
    }

    .exam-subtab-content {
        display: none;
    }

    .exam-subtab-content.active {
        display: block;
    }

    /* Notebook Cell Styles */
    .notebook-viewer {
        max-width: 100%;
    }

    .notebook-toc {
        background: var(--bg-white);
        border: 1px solid var(--border);
        border-radius: var(--radius-lg);
        padding: 20px 24px;
        margin-bottom: 24px;
    }

    .notebook-toc h3 {
        font-size: 14px;
        font-weight: 600;
        text-transform: uppercase;
        letter-spacing: 0.5px;
        color: var(--text-muted);
        margin-bottom: 12px;
    }

    .notebook-toc-list {
        list-style: none;
        padding: 0;
        margin: 0;
    }

    .notebook-toc-list li {
        margin-bottom: 8px;
    }

    .notebook-toc-list a {
        color: var(--text-secondary);
        text-decoration: none;
        font-size: 14px;
    }

    .notebook-toc-list a:hover {
        color: var(--primary);
    }

    .notebook-toc-list .toc-part {
        font-weight: 600;
        color: var(--text-primary);
        margin-right: 4px;
    }

    .nb-cell {
        margin-bottom: 16px;
        border: 1px solid var(--border);
        border-radius: var(--radius);
        overflow: hidden;
    }

    .nb-cell-markdown {
        background: var(--bg-white);
        padding: 20px 24px;
    }

    .nb-cell-markdown h1 {
        font-size: 28px;
        font-weight: 700;
        color: var(--text-primary);
        margin-top: 0;
        margin-bottom: 16px;
        padding-bottom: 8px;
        border-bottom: 2px solid var(--primary);
    }

    .nb-cell-markdown h2 {
        font-size: 22px;
        font-weight: 600;
        color: var(--text-primary);
        margin-top: 24px;
        margin-bottom: 12px;
    }

    .nb-cell-markdown h3 {
        font-size: 18px;
        font-weight: 600;
        color: var(--text-primary);
        margin-top: 20px;
        margin-bottom: 10px;
    }

    .nb-cell-markdown p {
        margin-bottom: 12px;
        line-height: 1.7;
        color: var(--text-secondary);
    }

    .nb-cell-markdown ul, .nb-cell-markdown ol {
        margin-bottom: 12px;
        padding-left: 24px;
    }

    .nb-cell-markdown li {
        margin-bottom: 6px;
        line-height: 1.6;
        color: var(--text-secondary);
    }

    .nb-cell-markdown table {
        width: 100%;
        border-collapse: collapse;
        margin: 16px 0;
        font-size: 14px;
    }

    .nb-cell-markdown th, .nb-cell-markdown td {
        border: 1px solid var(--border);
        padding: 10px 12px;
        text-align: left;
    }

    .nb-cell-markdown th {
        background: var(--bg-main);
        font-weight: 600;
        color: var(--text-primary);
    }

    .nb-cell-markdown code {
        background: var(--bg-main);
        padding: 2px 6px;
        border-radius: 4px;
        font-family: 'JetBrains Mono', monospace;
        font-size: 13px;
        color: var(--primary);
    }

    .nb-cell-markdown pre {
        background: #1e1e2e;
        padding: 16px;
        border-radius: var(--radius);
        overflow-x: auto;
        margin: 12px 0;
    }

    .nb-cell-markdown pre code {
        background: none;
        padding: 0;
        color: #cdd6f4;
    }

    .nb-cell-code {
        background: #1e1e2e;
    }

    .nb-cell-code-header {
        display: flex;
        justify-content: space-between;
        align-items: center;
        padding: 8px 16px;
        background: rgba(255,255,255,0.05);
        border-bottom: 1px solid rgba(255,255,255,0.1);
    }

    .nb-cell-code-label {
        font-size: 12px;
        font-weight: 500;
        color: #a6adc8;
        text-transform: uppercase;
        letter-spacing: 0.5px;
    }

    .nb-cell-code-content {
        padding: 16px;
        overflow-x: auto;
    }

    .nb-cell-code-content pre {
        margin: 0;
        font-family: 'JetBrains Mono', monospace;
        font-size: 13px;
        line-height: 1.5;
        color: #cdd6f4;
    }

    .nb-cell-output {
        background: #11111b;
        border-top: 1px solid rgba(255,255,255,0.1);
        padding: 12px 16px;
    }

    .nb-cell-output-label {
        font-size: 11px;
        font-weight: 500;
        color: #6c7086;
        text-transform: uppercase;
        letter-spacing: 0.5px;
        margin-bottom: 8px;
    }

    .nb-cell-output pre {
        font-family: 'JetBrains Mono', monospace;
        font-size: 12px;
        line-height: 1.5;
        color: #a6adc8;
        white-space: pre-wrap;
        margin: 0;
    }

    /* Answer Key Warning */
    .answer-key-warning {
        background: linear-gradient(135deg, #fef2f2 0%, #fee2e2 100%);
        border: 2px solid #dc2626;
        border-radius: var(--radius-lg);
        padding: 16px 24px;
        margin-bottom: 24px;
        display: flex;
        align-items: center;
        gap: 12px;
    }

    .answer-key-warning-icon {
        font-size: 32px;
    }

    .answer-key-warning-text h4 {
        color: #dc2626;
        font-size: 16px;
        font-weight: 700;
        margin-bottom: 4px;
    }

    .answer-key-warning-text p {
        color: #991b1b;
        font-size: 14px;
        margin: 0;
    }

    /* Lab Cards */
    .lab-card {
        background: var(--bg-white);
        border: 1px solid var(--border);
        border-radius: var(--radius-lg);
        overflow: hidden;
        transition: all var(--transition);
    }

    .lab-card:hover {
        box-shadow: var(--shadow-md);
        border-color: #2563EB;
        transform: translateY(-2px);
    }

    .btn-colab {
        display: flex;
        align-items: center;
        justify-content: center;
        gap: 10px;
        background: #F9AB00;
        color: #000;
        font-weight: 600;
        padding: 12px;
        border-radius: 6px;
        text-decoration: none;
        transition: all 0.2s;
    }

    .btn-colab:hover {
        background: #E69A00;
        transform: scale(1.02);
    }

    .btn-solution {
        display: flex;
        align-items: center;
        justify-content: center;
        gap: 8px;
        background: #10B981;
        color: white;
        font-weight: 500;
        padding: 12px;
        border-radius: 6px;
        text-decoration: none;
        font-size: 14px;
        transition: all 0.2s;
    }

    .btn-solution:hover {
        background: #059669;
        transform: scale(1.02);
    }

    .btn-secondary {
        flex: 1;
        display: flex;
        align-items: center;
        justify-content: center;
        gap: 8px;
        padding: 10px;
        font-size: 13px;
        border-radius: 6px;
        text-decoration: none;
        background: var(--bg-main);
        color: var(--text-primary);
        border: 1px solid var(--border);
        transition: all 0.2s;
    }

    .btn-secondary:hover {
        background: var(--bg-white);
        border-color: var(--primary);
        color: var(--primary);
    }

    @media (max-width: 768px) {
        .labs-grid {
            grid-template-columns: 1fr;
        }
    }