/* ================================
   CSS Variables & Base Styles
   ================================ */
:root {
    /* Warm Taupe & Clay palette */
    --color-cream: #FAF9F8;
    --color-cream-dark: #F1EFED;
    --color-terracotta: #796D68;
    --color-terracotta-dark: #635855;
    --color-sage: #8F847E;
    --color-sage-light: #B5AAA4;
    --color-charcoal: #2C2928;
    --color-charcoal-light: #504B48;
    --color-warm-gray: #7A7472;

    /* Typography */
    --font-serif: 'Source Serif 4', Georgia, serif;
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;

    /* Spacing */
    --space-xs: 0.5rem;
    --space-sm: 1rem;
    --space-md: 1.5rem;
    --space-lg: 2rem;
    --space-xl: 3rem;
    --space-2xl: 4rem;
    --space-3xl: 6rem;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 400ms ease;

    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);
}

/* ================================
   Reset & Base
   ================================ */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: var(--font-sans);
    font-size: 16px;
    line-height: 1.6;
    color: var(--color-charcoal);
    background-color: var(--color-cream);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: var(--color-terracotta);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--color-terracotta-dark);
}

/* ================================
   Typography
   ================================ */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-serif);
    font-weight: 600;
    line-height: 1.3;
    color: var(--color-charcoal);
}

h1 {
    font-size: clamp(2.5rem, 5vw, 3.5rem);
    letter-spacing: -0.02em;
}

h2 {
    font-size: clamp(1.75rem, 4vw, 2.5rem);
}

h3 {
    font-size: clamp(1.125rem, 2vw, 1.375rem);
}

p {
    margin-bottom: var(--space-sm);
}

p:last-child {
    margin-bottom: 0;
}

/* ================================
   Layout
   ================================ */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-md);
}

.section {
    padding: var(--space-3xl) 0;
}

.section-alt {
    background-color: var(--color-cream-dark);
}

.section-title {
    margin-bottom: var(--space-sm);
    position: relative;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background-color: var(--color-terracotta);
    margin-top: var(--space-sm);
}

.section-intro {
    font-size: 1.125rem;
    color: var(--color-warm-gray);
    max-width: 700px;
    margin-bottom: var(--space-xl);
}

/* ================================
   Navigation
   ================================ */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: rgba(249, 250, 251, 0.95);
    backdrop-filter: blur(10px);
    z-index: 1000;
    transition: box-shadow var(--transition-base);
}

.nav.scrolled {
    box-shadow: var(--shadow-md);
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--space-sm) var(--space-md);
}

.nav-logo {
    font-family: var(--font-serif);
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--color-charcoal);
    letter-spacing: -0.02em;
    opacity: 0;
    transition: opacity var(--transition-base);
    pointer-events: none;
}

.nav-logo.visible {
    opacity: 1;
    pointer-events: auto;
}

.nav-logo:hover {
    color: var(--color-terracotta);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--space-lg);
}

.nav-link {
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-charcoal-light);
    padding: var(--space-xs) 0;
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--color-terracotta);
    transition: width var(--transition-base);
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-terracotta);
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--space-xs);
}

.nav-toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background-color: var(--color-charcoal);
    transition: transform var(--transition-base), opacity var(--transition-fast);
}

/* ================================
   Hero Section
   ================================ */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding-top: 80px;
    background: linear-gradient(135deg, var(--color-cream) 0%, var(--color-cream-dark) 100%);
}

.hero-content {
    display: grid;
    grid-template-columns: 300px 1fr;
    gap: var(--space-2xl);
    align-items: center;
}

.hero-image {
}

.profile-photo {
    width: 100%;
    max-width: 300px;
    border-radius: 8px;
    box-shadow: var(--shadow-lg);
}

.hero-text h1 {
    color: var(--color-charcoal-light);
    margin-bottom: var(--space-xs);
}

.hero-title {
    font-size: 1.125rem;
    font-weight: 500;
    color: var(--color-terracotta);
    margin-bottom: var(--space-md);
}

.hero-intro {
    font-size: 0.95rem;
    line-height: 1.7;
    color: var(--color-charcoal-light);
    max-width: 600px;
    margin-bottom: var(--space-md);
}

.hero-links {
    display: flex;
    gap: var(--space-sm);
    flex-wrap: wrap;
}

/* ================================
   Buttons
   ================================ */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.875rem 1.75rem;
    font-family: var(--font-sans);
    font-size: 0.9375rem;
    font-weight: 500;
    border-radius: 6px;
    border: none;
    cursor: pointer;
    transition: all var(--transition-base);
}

.btn-primary {
    background-color: var(--color-terracotta);
    color: white;
}

.btn-primary:hover {
    background-color: var(--color-terracotta-dark);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background-color: transparent;
    color: var(--color-charcoal);
    border: 2px solid var(--color-charcoal);
}

.btn-secondary:hover {
    background-color: var(--color-charcoal);
    color: white;
}

/* ================================
   Research Section
   ================================ */
.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--space-md);
}

.research-card {
    background-color: white;
    padding: var(--space-lg);
    border-radius: 8px;
    box-shadow: var(--shadow-sm);
    transition: transform var(--transition-base), box-shadow var(--transition-base);
}

.research-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.research-tag {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    background-color: rgba(255, 255, 255, 0.2);
    padding: 0.25rem 0.75rem;
    border-radius: 4px;
    margin-bottom: var(--space-sm);
}

.research-card h3 {
    font-size: 1.125rem;
    margin-bottom: var(--space-xs);
}

.research-card h3 a {
    color: var(--color-charcoal);
    transition: color var(--transition-fast);
}

.research-card h3 a:hover {
    color: var(--color-terracotta);
}

.research-authors {
    font-size: 0.875rem;
    color: var(--color-warm-gray);
    font-style: italic;
    margin-bottom: var(--space-xs);
}

.research-venue {
    font-size: 0.875rem;
    color: var(--color-sage);
    font-weight: 500;
    margin-bottom: var(--space-sm);
}

.research-desc {
    font-size: 0.9375rem;
    color: var(--color-charcoal-light);
    line-height: 1.6;
}

/* Featured Working Paper with Figures */
.featured-working-paper {
    background-color: white;
    border-radius: 8px;
    box-shadow: var(--shadow-sm);
    overflow: hidden;
    margin-bottom: var(--space-lg);
    transition: box-shadow var(--transition-base);
}

.featured-working-paper:hover {
    box-shadow: var(--shadow-lg);
}

a.featured-data {
    text-decoration: none;
    color: inherit;
    display: block;
}

.featured-wp-header {
    background-color: var(--color-terracotta);
    padding: 0.625rem var(--space-lg);
}

.featured-wp-header .research-tag {
    background-color: transparent;
    color: white;
    padding: 0;
    margin: 0;
}

.featured-wp-body {
    display: grid;
    grid-template-columns: 1fr 1fr;
}

.featured-wp-text {
    padding: var(--space-lg);
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.featured-wp-text h3 {
    font-size: 1.25rem;
    margin-bottom: var(--space-xs);
}

.featured-wp-text .research-desc {
    margin-bottom: var(--space-md);
}

.featured-wp-text .btn-sm {
    padding: 0.625rem 1.25rem;
    font-size: 0.875rem;
}

.featured-wp-figures {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--space-md);
    background-color: white;
}

.featured-wp-figure img {
    max-width: 100%;
    height: auto;
    object-fit: contain;
}

/* Video thumbnail in featured card */
.featured-video-thumb {
    padding: 0;
    background-color: #000;
}

.video-thumb-link {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
    min-height: 280px;
    overflow: hidden;
}

.video-thumb-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.video-play-btn {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    opacity: 0.85;
    transition: opacity var(--transition-fast), transform var(--transition-fast);
    filter: drop-shadow(0 2px 8px rgba(0, 0, 0, 0.4));
}

.video-thumb-link:hover .video-play-btn {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1.1);
}

.research-subsection-title {
    font-size: 1.125rem;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--color-warm-gray);
    margin-top: var(--space-xl);
    margin-bottom: var(--space-md);
    padding-bottom: var(--space-xs);
    border-bottom: 1px solid rgba(0, 0, 0, 0.1);
}

/* Medical & Public Health Publications List */
.medical-pub-list {
    list-style: none;
    margin-top: var(--space-md);
}

.medical-pub-item {
    display: flex;
    flex-direction: column;
    padding: var(--space-sm) 0;
    border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}

.medical-pub-item:last-child {
    border-bottom: none;
}

.medical-pub-title {
    font-family: var(--font-serif);
    font-size: 1rem;
    font-weight: 600;
    color: var(--color-charcoal);
    line-height: 1.4;
    margin-bottom: 0.25rem;
}

.medical-pub-title a {
    color: var(--color-charcoal);
    transition: color var(--transition-fast);
}

.medical-pub-title a:hover {
    color: var(--color-terracotta);
}

.medical-pub-meta {
    font-size: 0.8125rem;
    color: var(--color-warm-gray);
    line-height: 1.5;
}

.medical-pub-meta em {
    color: var(--color-sage);
    font-weight: 500;
}

/* Collapsible "More" publications */
.more-publications {
    display: none;
    margin-top: var(--space-sm);
}

.more-publications.expanded {
    display: block;
}

.btn-more-pubs {
    display: inline-block;
    margin-top: var(--space-md);
    padding: 0.5rem 1.25rem;
    background-color: transparent;
    border: 1.5px solid var(--color-warm-gray);
    border-radius: 4px;
    font-family: var(--font-sans);
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--color-warm-gray);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.btn-more-pubs:hover {
    border-color: var(--color-terracotta);
    color: var(--color-terracotta);
}

/* ================================
   Data Section
   ================================ */
.data-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: var(--space-md);
}

.data-card {
    display: block;
    background-color: white;
    padding: var(--space-lg);
    border-radius: 8px;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-base);
    text-decoration: none;
}

.data-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--color-terracotta);
}

.data-card:hover .data-icon {
    color: var(--color-terracotta);
}

.data-icon {
    color: var(--color-sage);
    margin-bottom: var(--space-md);
    transition: color var(--transition-base);
}

.data-card h3 {
    font-size: 1.125rem;
    margin-bottom: var(--space-xs);
    color: var(--color-charcoal);
}

.data-card p {
    font-size: 0.9375rem;
    color: var(--color-warm-gray);
    margin-bottom: var(--space-sm);
}

.data-link {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-terracotta);
}

/* ================================
   Teaching Section
   ================================ */
.teaching-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: var(--space-md);
}

.course-card {
    background-color: white;
    padding: var(--space-lg);
    border-radius: 8px;
    box-shadow: var(--shadow-sm);
    border-left: 4px solid var(--color-sage);
    transition: border-color var(--transition-base);
}

.course-card:hover {
    border-left-color: var(--color-terracotta);
}

.course-number {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-sage);
    margin-bottom: var(--space-xs);
}

.course-card h3 {
    font-size: 1.125rem;
    margin-bottom: 0.25rem;
}

.course-term {
    display: block;
    font-size: 0.8125rem;
    color: var(--color-warm-gray);
    margin-bottom: var(--space-sm);
}

.course-card p {
    font-size: 0.9375rem;
    color: var(--color-charcoal-light);
}

.syllabus-link {
    margin-top: var(--space-sm);
}

/* ================================
   Media Section
   ================================ */
.media-layout {
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: var(--space-xl);
    margin-bottom: var(--space-xl);
}

.media-filters h3,
.media-articles h3 {
    font-size: 1rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-warm-gray);
    margin-bottom: var(--space-md);
}

.outlet-list {
    display: flex;
    flex-direction: column;
    gap: var(--space-xs);
}

.outlet {
    display: block;
    width: 100%;
    padding: 0.625rem 1rem;
    background-color: white;
    border: 2px solid transparent;
    border-radius: 4px;
    font-family: var(--font-sans);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-charcoal);
    box-shadow: var(--shadow-sm);
    cursor: pointer;
    text-align: left;
    transition: all var(--transition-fast);
}

.outlet:hover {
    border-color: var(--color-terracotta);
    color: var(--color-terracotta);
}

.outlet.active {
    background-color: var(--color-terracotta);
    color: white;
    border-color: var(--color-terracotta);
}

/* Article List */
.article-list {
    list-style: none;
    max-height: 500px;
    overflow: hidden;
    transition: max-height var(--transition-slow);
}

.article-list.expanded {
    max-height: none;
}

.article-item {
    display: grid;
    grid-template-columns: 80px 1fr auto;
    gap: var(--space-sm);
    align-items: baseline;
    padding: var(--space-sm) 0;
    border-bottom: 1px solid rgba(0, 0, 0, 0.08);
}

.article-item:last-child {
    border-bottom: none;
}

.article-item.hidden {
    display: none;
}

.article-date {
    font-size: 0.8125rem;
    color: var(--color-warm-gray);
    font-weight: 500;
}

.article-link {
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-charcoal);
    text-decoration: none;
    transition: color var(--transition-fast);
}

.article-link:hover {
    color: var(--color-terracotta);
}

.article-outlet {
    font-size: 0.8125rem;
    color: var(--color-sage);
    white-space: nowrap;
}

.btn-show-more {
    display: inline-block;
    margin-top: var(--space-md);
    padding: 0.625rem 1.25rem;
    background-color: transparent;
    border: 2px solid var(--color-charcoal);
    border-radius: 4px;
    font-family: var(--font-sans);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-charcoal);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.btn-show-more:hover {
    background-color: var(--color-charcoal);
    color: white;
}

.btn-show-more.hidden {
    display: none;
}

/* ================================
   Service Section
   ================================ */
.service-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-lg);
}

.service-item {
    padding: var(--space-lg);
    background-color: white;
    border-radius: 8px;
    box-shadow: var(--shadow-sm);
}

.service-item h3 {
    font-size: 1.125rem;
    margin-bottom: var(--space-xs);
}

.service-item h3 a {
    color: var(--color-charcoal);
    transition: color var(--transition-fast);
}

.service-item h3 a:hover {
    color: var(--color-terracotta);
}

.service-item > p:first-of-type {
    font-size: 0.875rem;
    color: var(--color-sage);
    font-weight: 500;
    margin-bottom: var(--space-sm);
}

.service-desc {
    font-size: 0.9375rem;
    color: var(--color-charcoal-light);
}

/* ================================
   Footer
   ================================ */
.footer {
    padding: var(--space-lg) 0;
    text-align: center;
    font-size: 0.875rem;
    color: var(--color-warm-gray);
}

/* ================================
   Animations
   ================================ */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in-up {
    animation: fadeInUp 0.6s ease forwards;
}

/* ================================
   Responsive Design
   ================================ */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 60px;
        left: 0;
        right: 0;
        background-color: var(--color-cream);
        flex-direction: column;
        padding: var(--space-md);
        gap: 0;
        box-shadow: var(--shadow-lg);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-base);
    }

    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav-menu li {
        border-bottom: 1px solid rgba(0, 0, 0, 0.08);
    }

    .nav-menu li:last-child {
        border-bottom: none;
    }

    .nav-link {
        display: block;
        padding: var(--space-sm) 0;
    }

    .nav-toggle {
        display: flex;
    }

    .nav-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .nav-toggle.active span:nth-child(2) {
        opacity: 0;
    }

    .nav-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }

    .hero {
        min-height: auto;
        padding: calc(80px + var(--space-xl)) 0 var(--space-xl);
    }

    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-image {
        position: static;
        display: flex;
        justify-content: center;
    }

    .profile-photo {
        max-width: 220px;
    }

    .hero-text {
        display: flex;
        flex-direction: column;
        align-items: center;
    }

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

    .hero-links {
        flex-direction: column;
    }

    .btn {
        width: 100%;
    }

    .section {
        padding: var(--space-2xl) 0;
    }

    .research-grid,
    .data-grid,
    .teaching-grid {
        grid-template-columns: 1fr;
    }

    .featured-wp-body {
        grid-template-columns: 1fr;
    }

    .media-layout {
        grid-template-columns: 1fr;
    }

    .outlet-list {
        flex-direction: row;
        flex-wrap: wrap;
    }

    .outlet {
        width: auto;
    }

    .article-item {
        grid-template-columns: 1fr;
        gap: var(--space-xs);
    }

    .article-outlet {
        display: block;
    }
}

@media (max-width: 480px) {
    :root {
        --space-md: 1rem;
        --space-lg: 1.5rem;
        --space-xl: 2rem;
        --space-2xl: 3rem;
        --space-3xl: 4rem;
    }

    .outlet-list {
        gap: var(--space-xs);
    }

    .outlet {
        font-size: 0.8125rem;
        padding: 0.375rem 0.75rem;
    }
}