/* ============================================================
                   1.  CSS CUSTOM PROPERTIES (Design Tokens)
                   ============================================================ */
        :root {
            /* Primary palette – navy & slate */
            --color-primary: #0a2a44;
            --color-primary-light: #1a3f6a;
            --color-primary-dark: #061c30;
            --color-accent: #2a7de1;
            --color-accent-hover: #1a5fb4;
            --color-slate: #2c3e50;
            --color-slate-light: #5a7a96;
            --color-gray-100: #f8f9fa;
            --color-gray-200: #e9ecef;
            --color-gray-300: #dee2e6;
            --color-gray-600: #6c757d;
            --color-gray-800: #343a40;
            --color-white: #ffffff;
            --color-text: #1e2a3a;

            /* Typography */
            --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
            --font-serif: 'Roboto Slab', 'Times New Roman', serif;

            /* Spacing */
            --spacing-sm: 0.5rem;
            --spacing-md: 1rem;
            --spacing-lg: 2rem;
            --spacing-xl: 3rem;

            /* Border radius */
            --radius-sm: 6px;
            --radius-md: 12px;
            --radius-lg: 20px;

            /* Shadows */
            --shadow-card: 0 2px 12px rgba(10, 42, 68, 0.08);
            --shadow-card-hover: 0 6px 24px rgba(10, 42, 68, 0.12);
            --shadow-nav: 0 2px 20px rgba(10, 42, 68, 0.15);

            /* Transitions */
            --transition-fast: 0.2s ease;
            --transition-med: 0.3s ease;
            --transition-slow: 0.4s ease;
        }

        /* ============================================================
                   2.  RESET & BASE
                   ============================================================ */
        *,
        *::before,
        *::after {
            box-sizing: border-box;
        }

        html {
            scroll-behavior: smooth;
        }

        body {
            font-family: var(--font-sans);
            color: var(--color-text);
            background: var(--color-gray-100);
            line-height: 1.7;
            padding-top: 60px;
            /* space for mobile nav */
        }

        /* ============================================================
                   3.  TYPOGRAPHY
                   ============================================================ */
        h1,
        h2,
        h3,
        h4,
        h5,
        h6 {
            font-family: var(--font-serif);
            font-weight: 600;
            color: var(--color-primary);
            letter-spacing: -0.01em;
            margin-top: 0;
        }

        h1 {
            font-size: 2.8rem;
            line-height: 1.2;
        }
        h2 {
            font-size: 2.0rem;
            line-height: 1.3;
            margin-bottom: 1.2rem;
        }
        h3 {
            font-size: 1.4rem;
            line-height: 1.4;
        }
        h4 {
            font-size: 1.15rem;
            font-weight: 600;
        }

        .section-title {
            display: flex;
            align-items: center;
            gap: 0.75rem;
            border-bottom: 3px solid var(--color-primary);
            padding-bottom: 0.6rem;
            margin-bottom: 1.8rem;
        }
        .section-title i {
            color: var(--color-accent);
            font-size: 1.6rem;
        }

        a {
            color: var(--color-accent);
            text-decoration: none;
            transition: color var(--transition-fast);
        }
        a:hover {
            color: var(--color-accent-hover);
            text-decoration: underline;
        }

        .text-muted {
            color: var(--color-gray-600) !important;
        }

        /* ============================================================
                   4.  SIDEBAR / NAVIGATION
                   ============================================================ */
        .navbar-custom {
            background: var(--color-primary) !important;
            box-shadow: var(--shadow-nav);
            padding: 0.6rem 1.2rem;
            transition: background var(--transition-med);
        }

        .navbar-custom .navbar-brand {
            font-family: var(--font-serif);
            font-weight: 700;
            color: var(--color-white) !important;
            font-size: 1.25rem;
            letter-spacing: 0.02em;
        }
        .navbar-custom .navbar-brand small {
            font-weight: 300;
            font-size: 0.75rem;
            opacity: 0.8;
            display: block;
            font-family: var(--font-sans);
        }

        .navbar-custom .navbar-nav .nav-link {
            color: rgba(255, 255, 255, 0.85) !important;
            font-weight: 500;
            font-size: 0.9rem;
            padding: 0.5rem 0.9rem;
            border-radius: var(--radius-sm);
            transition: background var(--transition-fast), color var(--transition-fast);
        }
        .navbar-custom .navbar-nav .nav-link:hover,
        .navbar-custom .navbar-nav .nav-link:focus {
            background: rgba(255, 255, 255, 0.12);
            color: var(--color-white) !important;
        }
        .navbar-custom .navbar-nav .nav-link i {
            margin-right: 0.4rem;
            width: 1.2rem;
            text-align: center;
        }

        /* Mobile toggler */
        .navbar-custom .navbar-toggler {
            border-color: rgba(255, 255, 255, 0.3);
            color: var(--color-white);
            padding: 0.3rem 0.7rem;
        }
        .navbar-custom .navbar-toggler-icon {
            background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba(255,255,255,0.85)' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/%3e%3c/svg%3e");
        }

        /* Desktop sidebar variant */
        @media (min-width: 992px) {
            body {
                padding-top: 0;
                padding-left: 280px;
            }
            .navbar-custom {
                position: fixed;
                top: 0;
                left: 0;
                width: 280px;
                height: 100vh;
                flex-direction: column;
                align-items: stretch;
                padding: 1.5rem 1rem;
                box-shadow: 2px 0 20px rgba(0, 0, 0, 0.12);
                overflow-y: auto;
                background: var(--color-primary) !important;
                z-index: 1030;
            }
            .navbar-custom .navbar-brand {
                text-align: center;
                margin-bottom: 1.5rem;
                padding: 0.5rem;
            }
            .navbar-custom .navbar-brand .brand-img {
                width: 110px;
                height: 110px;
                border-radius: 50%;
                border: 3px solid rgba(255, 255, 255, 0.25);
                object-fit: cover;
                margin-bottom: 0.6rem;
                display: block;
                margin-left: auto;
                margin-right: auto;
                background: var(--color-white);
                padding: 3px;
            }
            .navbar-custom .navbar-collapse {
                flex-grow: 0;
                width: 100%;
            }
            .navbar-custom .navbar-nav {
                flex-direction: column;
                width: 100%;
                gap: 0.15rem;
            }
            .navbar-custom .navbar-nav .nav-link {
                padding: 0.6rem 1rem;
                border-radius: var(--radius-sm);
                font-size: 0.9rem;
            }
            .navbar-custom .navbar-toggler {
                display: none;
            }
            .nav-footer {
                margin-top: auto;
                padding-top: 1rem;
                border-top: 1px solid rgba(255, 255, 255, 0.12);
                text-align: center;
                font-size: 0.7rem;
                color: rgba(255, 255, 255, 0.5);
            }
            .nav-footer a {
                color: rgba(255, 255, 255, 0.7);
            }
            .nav-footer a:hover {
                color: var(--color-white);
            }
        }

        @media (max-width: 991.98px) {
            .navbar-custom .navbar-brand .brand-img {
                width: 48px;
                height: 48px;
                border-radius: 50%;
                object-fit: cover;
                border: 2px solid rgba(255, 255, 255, 0.2);
                margin-right: 0.6rem;
            }
            .navbar-custom .navbar-brand {
                display: flex;
                align-items: center;
            }
            .navbar-custom .navbar-collapse {
                background: var(--color-primary-dark);
                border-radius: var(--radius-md);
                padding: 0.8rem;
                margin-top: 0.6rem;
            }
            .nav-footer {
                display: none;
            }
        }

        /* ============================================================
                   5.  MAIN CONTENT LAYOUT
                   ============================================================ */
        .main-content {
            max-width: 1100px;
            margin: 0 auto;
            padding: 1.2rem 1.2rem 3rem;
        }

        /* ============================================================
                   6.  CARDS & SECTIONS
                   ============================================================ */
        .section-card {
            background: var(--color-white);
            border-radius: var(--radius-md);
            box-shadow: var(--shadow-card);
            padding: 1.8rem 2rem;
            margin-bottom: 2rem;
            transition: box-shadow var(--transition-med), transform var(--transition-fast);
            border: 1px solid var(--color-gray-200);
        }
        .section-card:hover {
            box-shadow: var(--shadow-card-hover);
        }

        /* ============================================================
                   7.  COLLAPSIBLE SECTIONS  (details/summary)
                   ============================================================ */
        details.collapsible-section {
            display: block;
            margin-bottom: 0.25rem;
        }
        details.collapsible-section summary {
            display: flex;
            align-items: center;
            gap: 0.6rem;
            font-family: var(--font-serif);
            font-weight: 600;
            font-size: 1.2rem;
            color: var(--color-primary);
            cursor: pointer;
            padding: 0.6rem 0;
            list-style: none;
            user-select: none;
            transition: color var(--transition-fast);
            border-bottom: 2px solid transparent;
        }
        details.collapsible-section summary::-webkit-details-marker {
            display: none;
        }
        details.collapsible-section summary::before {
            content: '\f0fe';
            /* fa-plus-square */
            font-family: 'Font Awesome 6 Free';
            font-weight: 400;
            font-size: 1.2rem;
            color: var(--color-accent);
            transition: transform var(--transition-med);
            margin-right: 0.2rem;
            width: 1.4rem;
            text-align: center;
        }
        details.collapsible-section[open] summary::before {
            content: '\f146';
            /* fa-minus-square */
            font-weight: 400;
        }
        details.collapsible-section summary:hover {
            color: var(--color-accent-hover);
        }
        details.collapsible-section .collapse-content {
            padding-top: 1rem;
            animation: fadeSlideIn var(--transition-med) ease;
        }

        @keyframes fadeSlideIn {
            0% {
                opacity: 0;
                transform: translateY(-6px);
            }
            100% {
                opacity: 1;
                transform: translateY(0);
            }
        }

        /* When used inside a card, adjust spacing */
        .section-card details.collapsible-section summary {
            font-size: 1.1rem;
            padding: 0.4rem 0;
        }
        .section-card details.collapsible-section .collapse-content {
            padding-top: 0.6rem;
        }

        /* ============================================================
                   8.  PROFILE / BIO
                   ============================================================ */
        .profile-header {
            display: flex;
            flex-wrap: wrap;
            gap: 1.5rem;
            align-items: flex-start;
        }
        .profile-avatar {
            flex-shrink: 0;
        }
        .profile-avatar img {
            width: 130px;
            height: 130px;
            border-radius: 50%;
            object-fit: cover;
            border: 4px solid var(--color-primary);
            box-shadow: 0 4px 16px rgba(10, 42, 68, 0.15);
        }
        .profile-titles h1 {
            margin-bottom: 0.2rem;
        }
        .profile-titles .position {
            font-size: 1.15rem;
            font-weight: 500;
            color: var(--color-slate-light);
            margin-bottom: 0.3rem;
        }
        .profile-titles .institution {
            font-size: 1rem;
            color: var(--color-gray-600);
        }
        .profile-titles .institution a {
            color: var(--color-accent);
        }

        .profile-bio {
            margin-top: 1.2rem;
            font-size: 1.05rem;
            line-height: 1.8;
            color: var(--color-slate);
        }
        .profile-bio strong {
            color: var(--color-primary);
        }

        .research-tags {
            display: flex;
            flex-wrap: wrap;
            gap: 0.5rem;
            margin-top: 0.8rem;
        }
        .research-tags .tag {
            background: var(--color-gray-200);
            padding: 0.25rem 0.9rem;
            border-radius: 20px;
            font-size: 0.8rem;
            font-weight: 500;
            color: var(--color-primary);
            letter-spacing: 0.01em;
            transition: background var(--transition-fast), color var(--transition-fast);
        }
        .research-tags .tag:hover {
            background: var(--color-primary);
            color: var(--color-white);
        }

        .contact-links {
            display: flex;
            flex-wrap: wrap;
            gap: 0.8rem 1.6rem;
            margin-top: 1rem;
            padding-top: 1rem;
            border-top: 1px solid var(--color-gray-200);
        }
        .contact-links a {
            display: inline-flex;
            align-items: center;
            gap: 0.4rem;
            font-size: 0.95rem;
            color: var(--color-slate);
            transition: color var(--transition-fast);
        }
        .contact-links a:hover {
            color: var(--color-accent);
            text-decoration: none;
        }
        .contact-links a i {
            font-size: 1.2rem;
            width: 1.4rem;
            text-align: center;
            color: var(--color-primary);
        }
        .contact-links .social-icon {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            width: 40px;
            height: 40px;
            border-radius: 50%;
            background: var(--color-gray-200);
            color: var(--color-primary);
            transition: background var(--transition-fast), color var(--transition-fast), transform var(--transition-fast);
            font-size: 1.2rem;
        }
        .contact-links .social-icon:hover {
            background: var(--color-primary);
            color: var(--color-white);
            transform: translateY(-2px);
            text-decoration: none;
        }

        /* ============================================================
                   9.  PUBLICATIONS
                   ============================================================ */
        .pub-item {
            padding: 1rem 0;
            border-bottom: 1px solid var(--color-gray-200);
            transition: background var(--transition-fast);
        }
        .pub-item:last-child {
            border-bottom: 0;
        }
        .pub-item .pub-title {
            font-weight: 600;
            font-size: 1.05rem;
            color: var(--color-primary);
            margin-bottom: 0.15rem;
        }
        .pub-item .pub-authors {
            font-size: 0.92rem;
            color: var(--color-slate);
        }
        .pub-item .pub-venue {
            font-size: 0.85rem;
            color: var(--color-gray-600);
            font-style: italic;
        }
        .pub-item .pub-meta {
            display: flex;
            flex-wrap: wrap;
            gap: 0.6rem 1.2rem;
            margin-top: 0.3rem;
            font-size: 0.8rem;
        }
        .pub-item .pub-meta .badge-metric {
            background: var(--color-gray-200);
            padding: 0.1rem 0.6rem;
            border-radius: 12px;
            color: var(--color-slate);
            font-weight: 500;
        }
        .pub-item .pub-meta .badge-metric.q1 {
            background: #d4edda;
            color: #155724;
        }
        .pub-item .pub-meta .badge-metric.q2 {
            background: #cce5ff;
            color: #004085;
        }
        .pub-item .pub-meta .badge-metric.isc {
            background: #fff3cd;
            color: #856404;
        }
        .pub-item .pub-links {
            margin-top: 0.4rem;
            display: flex;
            flex-wrap: wrap;
            gap: 0.5rem 1rem;
        }
        .pub-item .pub-links a {
            font-size: 0.85rem;
            display: inline-flex;
            align-items: center;
            gap: 0.3rem;
        }
        .pub-item .pub-links a i {
            font-size: 0.9rem;
        }

        /* ============================================================
                   10. AWARDS & REVIEWS
                   ============================================================ */
        .award-list {
            list-style: none;
            padding: 0;
            margin: 0;
        }
        .award-list li {
            padding: 0.5rem 0;
            border-bottom: 1px solid var(--color-gray-200);
            display: flex;
            gap: 0.8rem;
            align-items: flex-start;
        }
        .award-list li:last-child {
            border-bottom: 0;
        }
        .award-list li i {
            color: #f1c40f;
            font-size: 1.2rem;
            margin-top: 0.15rem;
            min-width: 1.4rem;
            text-align: center;
        }

        .review-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
            gap: 0.8rem;
        }
        .review-grid .review-item {
            background: var(--color-gray-100);
            border-radius: var(--radius-sm);
            padding: 0.6rem 1rem;
            font-size: 0.9rem;
            border: 1px solid var(--color-gray-200);
            transition: background var(--transition-fast), border-color var(--transition-fast);
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }
        .review-grid .review-item:hover {
            background: var(--color-white);
            border-color: var(--color-accent);
        }
        .review-grid .review-item .rank-badge {
            font-weight: 600;
            font-size: 0.7rem;
            padding: 0.1rem 0.5rem;
            border-radius: 10px;
            background: var(--color-gray-300);
            color: var(--color-gray-800);
            flex-shrink: 0;
        }
        .review-grid .review-item .rank-badge.q1 {
            background: #d4edda;
            color: #155724;
        }
        .review-grid .review-item .rank-badge.q2 {
            background: #cce5ff;
            color: #004085;
        }
        .review-grid .review-item .rank-badge.q3 {
            background: #f8d7da;
            color: #721c24;
        }

        /* ============================================================
                   11. CONTACT FORM
                   ============================================================ */
        .contact-form .form-control {
            border-radius: var(--radius-sm);
            border: 1px solid var(--color-gray-300);
            padding: 0.7rem 1rem;
            font-size: 0.95rem;
            transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
        }
        .contact-form .form-control:focus {
            border-color: var(--color-accent);
            box-shadow: 0 0 0 3px rgba(42, 125, 225, 0.15);
        }
        .contact-form .btn-submit {
            background: var(--color-primary);
            color: var(--color-white);
            border: 0;
            padding: 0.6rem 2rem;
            border-radius: var(--radius-sm);
            font-weight: 500;
            transition: background var(--transition-fast), transform var(--transition-fast);
        }
        .contact-form .btn-submit:hover {
            background: var(--color-primary-light);
            transform: translateY(-2px);
        }

        /* ============================================================
                   12. RESPONSIVE UTILITIES
                   ============================================================ */
        @media (max-width: 576px) {
            .profile-header {
                flex-direction: column;
                align-items: center;
                text-align: center;
            }
            .profile-titles h1 {
                font-size: 2.0rem;
            }
            .section-card {
                padding: 1.2rem 1rem;
            }
            .review-grid {
                grid-template-columns: 1fr 1fr;
            }
            .contact-links {
                justify-content: center;
            }
        }
        @media (min-width: 577px) and (max-width: 991.98px) {
            .profile-header {
                flex-direction: row;
                align-items: center;
            }
        }

        /* ============================================================
                   13. PRINT STYLES (CV-friendly)
                   ============================================================ */
        @media print {
            .navbar-custom {
                display: none !important;
            }
            body {
                padding: 0 !important;
                background: white;
            }
            .section-card {
                box-shadow: none !important;
                border: 1px solid #ddd;
                break-inside: avoid;
            }
            .section-card:hover {
                box-shadow: none !important;
            }
            details.collapsible-section summary::before {
                display: none;
            }
            details.collapsible-section .collapse-content {
                display: block !important;
                animation: none !important;
            }
            .contact-links .social-icon {
                background: #eee !important;
            }
            .main-content {
                max-width: 100%;
                padding: 0.5in;
            }
        }

        /* ============================================================
                   14. MISC HELPERS
                   ============================================================ */
        .text-primary-custom {
            color: var(--color-primary) !important;
        }
        .bg-primary-custom {
            background: var(--color-primary) !important;
        }
        .gap-1 {
            gap: 0.5rem;
        }
        .gap-2 {
            gap: 1rem;
        }
        .mt-2 {
            margin-top: 0.8rem;
        }
        .mb-2 {
            margin-bottom: 0.8rem;
        }
        .fw-500 {
            font-weight: 500;
        }
        .fw-600 {
            font-weight: 600;
        }
        .fs-small {
            font-size: 0.85rem;
        }

        /* ============================================================
                   15. TEACHING / STUDENTS / PROJECTS (optional sections)
                   ============================================================ */
        .teaching-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
            gap: 1rem;
        }
        .teaching-grid .course-item {
            background: var(--color-gray-100);
            padding: 0.8rem 1.2rem;
            border-radius: var(--radius-sm);
            border-left: 4px solid var(--color-accent);
            transition: background var(--transition-fast), border-color var(--transition-fast);
        }
        .teaching-grid .course-item:hover {
            background: var(--color-white);
            border-color: var(--color-primary);
        }
        .teaching-grid .course-item .course-code {
            font-weight: 600;
            font-size: 0.8rem;
            color: var(--color-accent);
            text-transform: uppercase;
            letter-spacing: 0.03em;
        }
        .teaching-grid .course-item .course-name {
            font-weight: 500;
            color: var(--color-primary);
        }

        .student-list {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
            gap: 0.6rem;
        }
        .student-list .student-item {
            background: var(--color-gray-100);
            padding: 0.4rem 0.9rem;
            border-radius: var(--radius-sm);
            font-size: 0.9rem;
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }
        .student-list .student-item i {
            color: var(--color-accent);
            font-size: 0.8rem;
        }

        .project-item {
            padding: 0.6rem 0;
            border-bottom: 1px solid var(--color-gray-200);
        }
        .project-item:last-child {
            border-bottom: 0;
        }
        .project-item .project-title {
            font-weight: 600;
            color: var(--color-primary);
        }
        .project-item .project-role {
            font-size: 0.85rem;
            color: var(--color-gray-600);
        }
        .project-item .project-desc {
            font-size: 0.92rem;
            margin-top: 0.2rem;
            color: var(--color-slate);
        }

        /* CV button */
        .btn-cv {
            background: var(--color-primary);
            color: var(--color-white);
            border: 0;
            padding: 0.5rem 1.4rem;
            border-radius: var(--radius-sm);
            font-weight: 500;
            font-size: 0.9rem;
            transition: background var(--transition-fast), transform var(--transition-fast);
            display: inline-flex;
            align-items: center;
            gap: 0.5rem;
        }
        .btn-cv:hover {
            background: var(--color-primary-light);
            color: var(--color-white);
            transform: translateY(-2px);
            text-decoration: none;
        }
        .btn-cv i {
            font-size: 1rem;
        }

        /* h-index / citation metrics */
        .metric-badge {
            display: inline-flex;
            align-items: baseline;
            gap: 0.3rem;
            background: var(--color-gray-200);
            padding: 0.2rem 1rem;
            border-radius: 20px;
            font-size: 0.9rem;
            font-weight: 500;
            color: var(--color-primary);
        }
        .metric-badge .number {
            font-weight: 700;
            font-size: 1.1rem;
            color: var(--color-accent);
        }