/* ===================================================
   DESIGN TOKENS
   =================================================== */

:root {
    /* Colors */
    --color-bg:           #FAFAF8;
    --color-bg-alt:       #F2F0EC;
    --color-surface:      #FFFFFF;
    --color-text:         #2C2C2C;
    --color-text-muted:   #6B6B6B;
    --color-text-light:   #999999;
    --color-accent:       #3A7D5C;
    --color-accent-hover: #2C5F45;
    --color-accent-light: #E8F4ED;
    --color-border:       #E0DDD8;

    /* Typography */
    --font-serif: 'EB Garamond', Georgia, 'Times New Roman', serif;
    --font-sans:  'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-sm:  0.875rem;
    --font-size-base: 1rem;
    --font-size-lg:  1.125rem;
    --font-size-xl:  1.5rem;
    --font-size-2xl: 2rem;
    --font-size-3xl: 2.75rem;
    --line-height:   1.7;
    --line-height-heading: 1.2;

    /* Spacing */
    --space-xs:  0.25rem;
    --space-sm:  0.5rem;
    --space-md:  1rem;
    --space-lg:  2rem;
    --space-xl:  4rem;
    --space-2xl: 6rem;
    --space-section: 5rem;

    /* Layout */
    --container-max:  800px;
    --container-wide: 1000px;
    --nav-height:     64px;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 300ms ease;
    --transition-slow: 500ms ease;

    /* Borders & Shadows */
    --radius-sm: 4px;
    --radius-md: 8px;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
}


/* ===================================================
   RESET & BASE
   =================================================== */

*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: var(--nav-height);
}

body {
    font-family: var(--font-serif);
    font-size: var(--font-size-base);
    line-height: var(--line-height);
    color: var(--color-text);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

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

a:hover {
    color: var(--color-accent-hover);
}

h1, h2, h3, h4 {
    font-family: var(--font-serif);
    line-height: var(--line-height-heading);
    font-weight: 600;
}


/* ===================================================
   ACCESSIBILITY
   =================================================== */

.skip-link {
    position: absolute;
    top: -100%;
    left: var(--space-md);
    background: var(--color-accent);
    color: var(--color-surface);
    padding: var(--space-sm) var(--space-md);
    z-index: 10000;
    border-radius: var(--radius-sm);
    font-family: var(--font-sans);
    font-size: var(--font-size-sm);
}

.skip-link:focus {
    top: var(--space-sm);
    color: var(--color-surface);
}

a:focus-visible,
button:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 3px;
    border-radius: 2px;
}


/* ===================================================
   LAYOUT
   =================================================== */

.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--space-lg);
}

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

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

.section-heading {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--space-xl);
    position: relative;
    padding-bottom: var(--space-md);
}

.section-heading::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 40px;
    height: 3px;
    background-color: var(--color-accent);
    border-radius: 2px;
}


/* ===================================================
   NAVIGATION
   =================================================== */

.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--nav-height);
    background-color: rgba(250, 250, 248, 0.92);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-border);
    z-index: 1000;
    transition: box-shadow var(--transition-base);
}

.site-header.scrolled {
    box-shadow: var(--shadow-sm);
}

.nav-container {
    max-width: var(--container-wide);
    margin: 0 auto;
    padding: 0 var(--space-lg);
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

.nav-logo {
    font-family: var(--font-serif);
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--color-text);
}

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

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

.nav-menu a {
    font-family: var(--font-sans);
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    position: relative;
    padding: var(--space-xs) 0;
}

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

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--color-accent);
}

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

/* Hamburger */
.nav-toggle {
    display: none;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0;
}

.hamburger {
    display: block;
    width: 22px;
    height: 2px;
    background-color: var(--color-text);
    position: relative;
    transition: background-color var(--transition-fast);
}

.hamburger::before,
.hamburger::after {
    content: '';
    position: absolute;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: var(--color-text);
    transition: transform var(--transition-base);
}

.hamburger::before {
    top: -7px;
}

.hamburger::after {
    top: 7px;
}

/* Hamburger open state */
.nav-toggle[aria-expanded="true"] .hamburger {
    background-color: transparent;
}

.nav-toggle[aria-expanded="true"] .hamburger::before {
    top: 0;
    transform: rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .hamburger::after {
    top: 0;
    transform: rotate(-45deg);
}


/* ===================================================
   HERO (SPLIT LAYOUT)
   =================================================== */

.hero-section {
    padding-top: calc(var(--nav-height) + var(--space-2xl));
    padding-bottom: var(--space-xl);
}

.hero-split {
    display: grid;
    grid-template-columns: 320px 1fr;
    gap: var(--space-xl);
    align-items: start;
    max-width: var(--container-wide);
}

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

.hero-image {
    max-width: 200px;
    margin: 0 auto var(--space-lg);
}

.hero-image img {
    width: 100%;
    border-radius: 50%;
    aspect-ratio: 1;
    object-fit: cover;
    object-position: center 20%;
}

.hero-left h1 {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    margin-bottom: var(--space-sm);
}

.hero-title {
    font-family: var(--font-sans);
    font-size: var(--font-size-base);
    color: var(--color-accent);
    font-weight: 500;
    margin-bottom: var(--space-xs);
}

.hero-institution {
    font-family: var(--font-sans);
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
    margin-bottom: var(--space-lg);
}

.hero-links {
    font-family: var(--font-sans);
    font-size: var(--font-size-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
    gap: var(--space-sm);
}

.hero-link-sep {
    color: var(--color-text-light);
}

/* Right side — About Me */
.hero-right {
    padding-top: var(--space-sm);
}

.hero-right .section-heading {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--space-lg);
}


/* ===================================================
   ABOUT
   =================================================== */

.about-content p {
    font-size: var(--font-size-lg);
    margin-bottom: var(--space-lg);
}

.about-content p:last-child {
    margin-bottom: 0;
}


/* ===================================================
   RESEARCH
   =================================================== */

.research-grid {
    display: grid;
    gap: var(--space-lg);
}

.research-area {
    padding: var(--space-lg);
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    transition: transform var(--transition-base), box-shadow var(--transition-base);
}

.research-area:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.research-area h3 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--space-sm);
    color: var(--color-accent);
}

.research-area p {
    color: var(--color-text-muted);
}


/* ===================================================
   PUBLICATIONS
   =================================================== */

.pub-year {
    font-family: var(--font-sans);
    font-size: var(--font-size-sm);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-accent);
    margin-top: var(--space-xl);
    margin-bottom: var(--space-lg);
    padding-bottom: var(--space-sm);
    border-bottom: 2px solid var(--color-accent);
}

.pub-year:first-of-type {
    margin-top: 0;
}

.publication-list {
    list-style: none;
}

.publication-item {
    padding: var(--space-lg) 0;
    border-bottom: 1px solid var(--color-border);
}

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

.pub-citation {
    font-size: var(--font-size-base);
    line-height: var(--line-height);
    padding-left: 2rem;
    text-indent: -2rem;
}

.pub-links {
    margin-top: var(--space-sm);
    padding-left: 2rem;
    display: flex;
    gap: var(--space-sm);
}

.pub-link {
    font-family: var(--font-sans);
    font-size: var(--font-size-sm);
    color: var(--color-accent);
    padding: var(--space-xs) var(--space-sm);
    border: 1px solid var(--color-accent);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
    font-weight: 500;
}

.pub-link:hover {
    background-color: var(--color-accent);
    color: var(--color-surface);
}


/* ===================================================
   POSTERS
   =================================================== */

.posters-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-lg);
}

.poster-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    overflow: hidden;
    display: flex;
    flex-direction: column;
    transition: transform var(--transition-base), box-shadow var(--transition-base);
}

.poster-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.poster-thumb {
    display: block;
    aspect-ratio: 4 / 3;
    background-color: var(--color-bg-alt);
    border-bottom: 1px solid var(--color-border);
    overflow: hidden;
    position: relative;
}

.poster-thumb img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center top;
    transition: transform var(--transition-base);
}

.poster-card:hover .poster-thumb img {
    transform: scale(1.03);
}

.poster-placeholder {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-accent);
    background: linear-gradient(135deg, var(--color-accent-light) 0%, var(--color-bg-alt) 100%);
}

.poster-pdf-preview {
    width: 100%;
    height: 100%;
    border: none;
    display: block;
    pointer-events: none;
    background-color: var(--color-bg-alt);
}

.poster-body {
    padding: var(--space-lg);
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
    flex: 1;
}

.poster-body h3 {
    font-size: var(--font-size-lg);
    line-height: 1.35;
}

.poster-body h3 a {
    color: var(--color-text);
}

.poster-body h3 a:hover {
    color: var(--color-accent);
}

.poster-meta {
    font-family: var(--font-sans);
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
}

.poster-project-link {
    font-family: var(--font-sans);
    font-size: var(--font-size-sm);
    font-weight: 500;
    display: inline-flex;
    align-items: center;
    gap: var(--space-xs);
    margin-top: auto;
    padding-top: var(--space-sm);
}

.poster-project-link svg {
    transition: transform var(--transition-fast);
}

.poster-project-link:hover svg {
    transform: translateX(3px);
}


/* ===================================================
   PROJECTS
   =================================================== */

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-lg);
}

.project-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    overflow: hidden;
    display: flex;
    flex-direction: column;
    transition: transform var(--transition-base), box-shadow var(--transition-base);
}

.project-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.project-card-body {
    padding: var(--space-lg);
    flex: 1;
}

.project-card-body h3 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--space-sm);
}

.project-card-body p {
    color: var(--color-text-muted);
    margin-bottom: var(--space-md);
}

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
}

.tag {
    font-family: var(--font-sans);
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--color-accent);
    background-color: var(--color-accent-light);
    padding: var(--space-xs) var(--space-sm);
    border-radius: var(--radius-sm);
}

.project-link {
    display: block;
    padding: var(--space-md) var(--space-lg);
    font-family: var(--font-sans);
    font-size: var(--font-size-sm);
    font-weight: 500;
    border-top: 1px solid var(--color-border);
    transition: background-color var(--transition-fast);
}

.project-link:hover {
    background-color: var(--color-accent-light);
}


/* ===================================================
   CV TIMELINE
   =================================================== */

.cv-download-btn {
    display: inline-flex;
    align-items: center;
    gap: var(--space-sm);
    font-family: var(--font-sans);
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-surface);
    background-color: var(--color-accent);
    padding: var(--space-sm) var(--space-lg);
    border-radius: var(--radius-sm);
    transition: background-color var(--transition-fast);
    margin-bottom: var(--space-xl);
}

.cv-download-btn:hover {
    background-color: var(--color-accent-hover);
    color: var(--color-surface);
}

.cv-category {
    margin-bottom: var(--space-xl);
}

.cv-category:last-child {
    margin-bottom: 0;
}

.cv-category > h3 {
    font-family: var(--font-sans);
    font-size: var(--font-size-sm);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-accent);
    margin-bottom: var(--space-lg);
    padding-bottom: var(--space-sm);
    border-bottom: 2px solid var(--color-accent);
}

.timeline-item {
    display: grid;
    grid-template-columns: 150px 1fr;
    gap: var(--space-lg);
    padding: var(--space-md) 0;
    border-bottom: 1px solid var(--color-border);
}

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

.timeline-year {
    font-family: var(--font-sans);
    font-size: var(--font-size-sm);
    color: var(--color-text-light);
    font-weight: 500;
    padding-top: 2px;
}

.timeline-content strong {
    display: block;
    margin-bottom: var(--space-xs);
}

.timeline-content p {
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
    font-family: var(--font-sans);
}


/* ===================================================
   CONTACT
   =================================================== */

.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-xl);
}

.contact-info p {
    font-family: var(--font-sans);
    font-size: var(--font-size-base);
    color: var(--color-text-muted);
    line-height: 1.8;
    margin-bottom: var(--space-lg);
}

.contact-email {
    font-family: var(--font-sans);
    font-size: var(--font-size-lg);
    font-weight: 500;
}

.contact-links {
    display: flex;
    flex-direction: column;
    gap: var(--space-md);
}

.contact-links a {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-family: var(--font-sans);
    font-size: var(--font-size-base);
    color: var(--color-text-muted);
    transition: color var(--transition-fast);
}

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

.contact-links svg {
    flex-shrink: 0;
}


/* ===================================================
   FOOTER
   =================================================== */

.site-footer {
    padding: var(--space-lg) 0;
    border-top: 1px solid var(--color-border);
    text-align: center;
}

.site-footer p {
    font-family: var(--font-sans);
    font-size: var(--font-size-sm);
    color: var(--color-text-light);
}


/* ===================================================
   SCROLL ANIMATIONS
   =================================================== */

.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity var(--transition-slow), transform var(--transition-slow);
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}


/* ===================================================
   REDUCED MOTION
   =================================================== */

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    .fade-in {
        opacity: 1;
        transform: none;
        transition: none;
    }

    .research-area,
    .project-card {
        transition: none;
    }
}


/* ===================================================
   RESPONSIVE — MOBILE (<768px)
   =================================================== */

@media (max-width: 767px) {
    :root {
        --space-section: 3.5rem;
    }

    .nav-toggle {
        display: flex;
    }

    .nav-menu {
        position: fixed;
        top: var(--nav-height);
        left: 0;
        right: 0;
        bottom: 0;
        background-color: var(--color-bg);
        flex-direction: column;
        align-items: center;
        justify-content: center;
        gap: var(--space-xl);
        transform: translateX(100%);
        transition: transform var(--transition-base);
    }

    .nav-menu.open {
        transform: translateX(0);
    }

    .hero-section {
        padding-top: calc(var(--nav-height) + var(--space-xl));
    }

    .hero-split {
        grid-template-columns: 1fr;
        gap: var(--space-lg);
    }

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

    .hero-image {
        max-width: 150px;
    }

    .hero-left h1 {
        font-size: var(--font-size-xl);
    }

    .section-heading {
        font-size: var(--font-size-xl);
    }

    .section-heading::after {
        left: 50%;
        transform: translateX(-50%);
    }

    .section-alt .section-heading::after,
    .section:not(.section-alt) .section-heading::after {
        left: 0;
        transform: none;
    }

    .pub-citation {
        padding-left: 1.5rem;
        text-indent: -1.5rem;
    }

    .pub-links {
        padding-left: 1.5rem;
    }

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

    .contact-grid {
        grid-template-columns: 1fr;
        gap: var(--space-lg);
    }

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


/* ===================================================
   RESPONSIVE — TABLET (768px+)
   =================================================== */

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


/* ===================================================
   RESPONSIVE — DESKTOP (1024px+)
   =================================================== */

@media (min-width: 1024px) {
    .container {
        max-width: var(--container-wide);
    }

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

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

    .hero-split {
        max-width: 1100px;
    }
}


/* ===================================================
   RESPONSIVE — WIDE DESKTOP (1280px+)
   =================================================== */

@media (min-width: 1280px) {
    .container {
        max-width: 1100px;
    }

    .hero-split {
        max-width: 1200px;
        grid-template-columns: 340px 1fr;
    }
}