:root {
    /* Columbia Business School Brand Colors */
    --cbs-blue: #009BDB;
    --cbs-blue-90: #002230;
    --cbs-blue-80: #00435F;
    --cbs-blue-70: #006088;
    --cbs-blue-60: #0078AB;
    --cbs-blue-50: #008CC6;
    --cbs-blue-40: #009BDB;
    --cbs-blue-30: #2FB3EA;
    --cbs-blue-20: #6BCCF5;
    --cbs-blue-10: #B1E5FB;
    --cbs-blue-5: #D8F2FD;

    --cbs-gray-90: #181A1C;
    --cbs-gray-80: #42474C;
    --cbs-gray-70: #687078;
    --cbs-gray-60: #89939C;
    --cbs-gray-50: #A6AFB9;
    --cbs-gray-40: #BEC7D0;
    --cbs-gray-30: #D2D9E1;
    --cbs-gray-20: #E3E8EE;
    --cbs-gray-10: #F1F4F7;
    --cbs-gray-5: #F8FAFB;

    /* Light Mode (default) */
    --primary-color: var(--cbs-blue-80);
    --primary-light: var(--cbs-blue);
    --primary-accent: var(--cbs-blue);
    --primary-subtle: rgba(0, 155, 219, 0.08);

    /* Text Colors */
    --text-main: var(--cbs-gray-90);
    --text-muted: var(--cbs-gray-70);
    --text-light: var(--cbs-gray-50);

    /* Backgrounds */
    --bg-body: #ffffff;
    --bg-surface: #ffffff;
    --bg-alt: var(--cbs-gray-5);

    /* Borders */
    --border-color: var(--cbs-gray-20);

    /* Typography */
    --font-sans: 'Public Sans', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-display: 'Spectral', Georgia, serif;

    /* Spacing */
    --navbar-height: 72px;

    /* Shadows */
    --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.04), 0 1px 2px -1px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.04), 0 2px 4px -2px rgba(0, 0, 0, 0.04);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.04), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
    --shadow-hover: 0 20px 25px -5px rgba(0, 0, 0, 0.06), 0 8px 10px -6px rgba(0, 0, 0, 0.06);

    /* Transitions */
    --transition-base: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);

    /* Color scheme for system preference detection */
    color-scheme: light dark;
}


/* Reset & Base */
html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    color: var(--text-main);
    background-color: var(--bg-body);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    padding-top: var(--navbar-height);
    transition: background-color 0.3s ease, color 0.3s ease;
}

::selection {
    background: var(--primary-accent);
    color: #fff;
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-display);
    font-weight: 700;
    color: var(--primary-color);
    line-height: 1.2;
    margin-bottom: 1rem;
    letter-spacing: -0.02em;
}

p {
    margin-bottom: 1.5rem;
}

a {
    color: var(--primary-accent);
    text-decoration: none;
    transition: var(--transition-base);
}

a:hover {
    color: var(--primary-light);
}


/* Navbar */
.navbar {
    height: var(--navbar-height);
    background: rgba(255, 255, 255, 0.92) !important;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid rgba(0, 0, 0, 0.04);
    padding: 0 !important;
    transition: var(--transition-base);
}


.navbar-brand {
    font-family: var(--font-display);
    font-weight: 700;
    color: var(--primary-color) !important;
    font-size: 1.4rem;
    letter-spacing: -0.02em;
}

.navbar-nav {
    gap: 0.5rem;
    align-items: center;
}

.nav-link {
    font-weight: 500;
    color: var(--text-muted) !important;
    font-size: 0.95rem;
    padding: 0.5rem 1rem !important;
    border-radius: 6px;
    transition: var(--transition-base);
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary-color) !important;
    background: var(--primary-subtle);
}

@media (max-width: 991.98px) {
    .navbar-collapse {
        background: var(--bg-surface);
        padding: 1.5rem;
        border-radius: 12px;
        box-shadow: var(--shadow-lg);
        margin-top: 1rem;
        border: 1px solid var(--border-color);
    }

    .navbar-nav {
        align-items: stretch;
    }
}

/* Hero Section */
.hero-section {
    padding: 5rem 0 4rem;
    background: linear-gradient(180deg, var(--bg-body) 0%, var(--bg-alt) 100%);
    min-height: calc(100vh - var(--navbar-height) - 100px);
    display: flex;
    align-items: center;
}

.hero-grid {
    display: grid;
    grid-template-columns: 320px 1fr;
    gap: 4rem;
    align-items: start;
}

.hero-image img {
    width: 100%;
    border-radius: 8px;
}

.hero-headline {
    font-size: 3.25rem;
    line-height: 1.1;
    margin-bottom: 0.75rem;
    letter-spacing: -0.03em;
}

.hero-subtitle {
    font-family: var(--font-sans);
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--text-muted);
    margin-bottom: 2rem;
    line-height: 1.5;
}

.hero-bio {
    font-size: 1.05rem;
    line-height: 1.75;
    color: var(--text-main);
    margin-bottom: 1.5rem;
}

.hero-bio a {
    color: var(--primary-accent);
    border-bottom: 1px solid transparent;
    transition: border-color 0.2s;
}

.hero-bio a:hover {
    border-bottom-color: var(--primary-accent);
}

/* Social Links */
.social-links {
    display: flex;
    gap: 0.75rem;
    margin-top: 2rem;
}

.social-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 42px;
    height: 42px;
    border-radius: 10px;
    background: var(--bg-alt);
    border: 1px solid var(--border-color);
    color: var(--text-muted);
    transition: var(--transition-base);
}

.social-link:hover {
    background: var(--primary-accent);
    border-color: var(--primary-accent);
    color: white;
}

.social-link i,
.social-link svg {
    font-size: 1rem;
    width: 1rem;
    height: 1rem;
}

@media (max-width: 768px) {
    .hero-section {
        min-height: auto;
        padding: 3rem 0;
    }

    .hero-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .hero-image {
        max-width: 220px;
        margin: 0 auto;
    }

    .hero-headline {
        font-size: 2.5rem;
        text-align: center;
    }

    .hero-subtitle {
        text-align: center;
    }

    .hero-content {
        text-align: left;
    }

    .social-links {
        justify-content: center;
    }
}

/* Featured Project Card */
.featured-card {
    background: linear-gradient(135deg, var(--cbs-blue-80) 0%, var(--cbs-blue-90) 100%);
    border-radius: 16px;
    padding: 3rem;
    color: white;
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 3rem;
    align-items: center;
}

.featured-card h1,
.featured-card h3 {
    font-size: 1.75rem;
    color: white;
    margin-bottom: 1rem;
}

.featured-card p {
    opacity: 0.9;
    line-height: 1.7;
    max-width: 700px;
    margin-bottom: 1.5rem;
}

.project-tagline {
    font-size: 1.15rem;
    margin-bottom: 2rem;
}

.featured-stats {
    display: flex;
    gap: 2.5rem;
    flex-wrap: wrap;
}

.stat {
    text-align: center;
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    display: block;
    font-family: var(--font-display);
}

.stat-label {
    font-size: 0.8rem;
    opacity: 0.8;
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

.featured-cta {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    background: white;
    color: var(--cbs-blue-80);
    padding: 1rem 1.75rem;
    border-radius: 8px;
    font-weight: 600;
    transition: transform 0.2s, box-shadow 0.2s;
    text-decoration: none;
    white-space: nowrap;
}

.featured-cta:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0,0,0,0.2);
    color: var(--cbs-blue-80);
}

@media (max-width: 992px) {
    .featured-card {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .featured-stats {
        gap: 1.5rem;
    }
}

/* Project Page (Politics at Work) */
.project-page {
    padding: 3rem 0 4rem;
}

.project-hero {
    margin-bottom: 3rem;
}

.project-description {
    background: var(--bg-surface);
}

.description-content {
    max-width: 960px;
}

.description-content h2 {
    font-size: 1.75rem;
    margin-bottom: 1.5rem;
}

.description-content h3 {
    font-size: 1.25rem;
    margin-top: 2.5rem;
    margin-bottom: 1rem;
}

.description-content p {
    font-size: 1.05rem;
    line-height: 1.8;
    color: var(--text-main);
}

.feature-list {
    list-style: none;
    padding: 0;
    margin: 1.5rem 0;
}

.feature-list li {
    padding: 0.75rem 0;
    padding-left: 1.5rem;
    position: relative;
    border-bottom: 1px solid var(--border-color);
}

.feature-list li:last-child {
    border-bottom: none;
}

.feature-list li::before {
    content: "→";
    position: absolute;
    left: 0;
    color: var(--primary-accent);
    font-weight: 600;
}

.project-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin-top: 2.5rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
}

/* Surface Cards */
.surface-card {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    transition: var(--transition-base);
    height: 100%;
    display: flex;
    flex-direction: column;
}

.surface-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-hover);
    border-color: transparent;
}

/* Research Page Styles */
.research-page {
    padding-top: 3rem;
    padding-bottom: 4rem;
    min-height: calc(100vh - var(--navbar-height));
}

.page-header {
    margin-bottom: 2rem;
}

.page-title {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

.page-subtitle {
    color: var(--text-muted);
    font-size: 1.1rem;
}

/* Paper Grid */
.paper-grid {
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

/* Paper Cards */
.paper-card {
    padding: 0;
    border-radius: 12px;
    overflow: hidden;
    border-left: 4px solid var(--primary-accent);
}

.paper-card:hover {
    transform: translateY(-3px);
    border-left-color: var(--cbs-blue-60);
}

.paper-content {
    padding: 1.75rem 2rem;
    display: flex;
    flex-direction: column;
}

.paper-card-header {
    margin-bottom: 0.5rem;
}

/* Paper Labels */
.paper-label {
    font-size: 0.7rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    font-weight: 700;
    padding: 4px 10px;
    border-radius: 4px;
    margin-bottom: 0.5rem;
    display: inline-block;
    margin-right: 0.5rem;
}

.paper-label--jmp {
    background: #fef3c7;
    color: #92400e;
}

.paper-label--published {
    background: #d1fae5;
    color: #065f46;
}

.paper-label--working {
    background: var(--cbs-blue-5);
    color: var(--cbs-blue-80);
}

.paper-label--review {
    background: #fce7f3;
    color: #9d174d;
}


.paper-journal-highlight {
    font-family: var(--font-display);
    font-style: italic;
    color: var(--text-muted);
    font-size: 1rem;
    margin-bottom: 0.4rem;
}

.paper-title {
    font-size: 1.25rem;
    margin-bottom: 0.25rem;
    line-height: 1.35;
}

.paper-meta {
    margin-bottom: 0.5rem;
}

.paper-authors {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.paper-description {
    color: var(--text-main);
    font-size: 0.95rem;
    line-height: 1.6;
    margin-bottom: 0;
    margin-top: 0.5rem;
}

/* Paper Awards */
.paper-awards {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 0.75rem;
}

.paper-award {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    font-size: 0.8rem;
    color: #b45309;
    background: #fef3c7;
    padding: 0.25rem 0.6rem;
    border-radius: 4px;
    font-weight: 500;
}

.paper-award i {
    font-size: 0.7rem;
}


/* Paper Actions */
.paper-actions {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
    align-items: center;
    margin-top: 1rem;
}

.paper-action-group {
    display: flex;
    gap: 0.5rem;
}

.paper-action-link {
    font-size: 0.85rem;
    padding: 0.4rem 0.9rem;
}

.paper-toggle {
    white-space: nowrap;
    padding: 0.4rem 0.9rem;
    font-size: 0.85rem;
}

.paper-toggle-icon {
    transition: transform 0.3s ease;
    margin-left: 0.25rem;
    font-size: 0.7rem;
}

.paper-toggle[aria-expanded="true"] .paper-toggle-icon,
.paper-toggle.is-open .paper-toggle-icon {
    transform: rotate(180deg);
}

.paper-abstract {
    margin-top: 1.25rem;
    padding-top: 1.25rem;
    border-top: 1px solid var(--border-color);
    color: var(--text-muted);
    font-size: 0.95rem;
    line-height: 1.7;
    text-align: justify;
}

.paper-abstract p {
    margin-bottom: 0;
}

/* Empty State */
.paper-empty {
    text-align: center;
    padding: 3rem;
    color: var(--text-muted);
}

/* Buttons */
.btn {
    padding: 0.75rem 1.5rem;
    font-weight: 600;
    border-radius: 999px;
    transition: all 0.2s ease;
    font-size: 0.95rem;
}

.btn:hover {
    transform: translateY(-1px);
}

.btn:focus,
.btn:active {
    outline: none !important;
    box-shadow: none !important;
}

.btn-primary {
    background-color: var(--primary-accent);
    border: 1px solid var(--primary-accent);
    color: #fff;
}

.btn-primary:hover {
    background-color: var(--cbs-blue-60);
    border-color: var(--cbs-blue-60);
    color: #fff;
}

.btn-outline-primary {
    background: transparent;
    color: var(--primary-accent);
    border: 1px solid var(--primary-accent);
}

.btn-outline-primary:hover {
    background: var(--primary-accent);
    color: #fff;
    border-color: var(--primary-accent);
}

.btn-sm {
    padding: 0.4rem 0.9rem;
    font-size: 0.85rem;
}

/* CV Page */
.cv-section {
    padding: 3rem 0 4rem;
}

.cv-header {
    text-align: center;
    margin-bottom: 2rem;
}

.cv-actions {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 2rem;
}

.cv-viewer {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    overflow: hidden;
    height: 85vh;
    min-height: 600px;
}

.cv-viewer iframe {
    width: 100%;
    height: 100%;
    border: none;
}

/* Footer */
footer {
    padding: 3rem 0;
    background: var(--bg-surface);
    border-top: 1px solid var(--border-color);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.footer-copyright {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-bottom: 0;
}

.footer-links {
    display: flex;
    gap: 1.5rem;
}

.footer-links a {
    color: var(--text-muted);
    font-size: 0.9rem;
    font-weight: 500;
}

.footer-links a:hover {
    color: var(--primary-accent);
}

@media (max-width: 768px) {
    .footer-content {
        flex-direction: column;
        text-align: center;
    }
}

/* Animations */
.fade-in {
    opacity: 0;
    animation: fadeIn 0.6s cubic-bezier(0.4, 0, 0.2, 1) forwards;
}

.fade-in-1 { animation-delay: 0.1s; }
.fade-in-2 { animation-delay: 0.2s; }
.fade-in-3 { animation-delay: 0.3s; }

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(15px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Focus styles for accessibility */
:focus-visible {
    outline: 2px solid var(--primary-accent);
    outline-offset: 2px;
}

button:focus-visible,
a:focus-visible {
    outline: 2px solid var(--primary-accent);
    outline-offset: 2px;
}

/* Wider container for project pages */
.container-wide {
    max-width: 1100px;
    width: 100%;
    padding-right: var(--bs-gutter-x, 0.75rem);
    padding-left: var(--bs-gutter-x, 0.75rem);
    margin-right: auto;
    margin-left: auto;
}

@media (min-width: 1200px) {
    .container-wide {
        max-width: 1140px;
    }
}

@media (min-width: 1400px) {
    .container-wide {
        max-width: 1200px;
    }
}