:root {
    /* Light theme (default) */
    --bg: #fafafa;
    --bg-secondary: #ffffff;
    --surface: #ffffff;
    --border: #e5e5e5;
    --text: #171717;
    --text-secondary: #525252;
    --text-muted: #737373;
    --accent: #2563eb;
    --accent-hover: #1d4ed8;
    --accent-light: #dbeafe;
    --shadow: rgba(0, 0, 0, 0.08);
}

[data-theme="dark"] {
    --bg: #0a0a0b;
    --bg-secondary: #111113;
    --surface: #18181b;
    --border: #27272a;
    --text: #fafafa;
    --text-secondary: #a1a1aa;
    --text-muted: #71717a;
    --accent: #60a5fa;
    --accent-hover: #3b82f6;
    --accent-light: rgba(96, 165, 250, 0.1);
    --shadow: rgba(0, 0, 0, 0.3);
}

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

html {
    scroll-behavior: smooth;
}

/* Fluid Background */
.fluid-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: -1;
}

body {
    font-family: 'DM Sans', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    font-size: 16px;
    min-height: 100vh;
    transition: background-color 0.3s, color 0.3s;
}

/* Navigation */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    padding: 1rem 2rem;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    transition: background-color 0.3s, border-color 0.3s;
}

.nav-inner {
    max-width: 1100px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-family: 'Crimson Pro', Georgia, serif;
    font-size: 1.25rem;
    font-weight: 500;
    color: var(--text);
    text-decoration: none;
    letter-spacing: -0.01em;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 2rem;
}

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

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    transition: color 0.2s;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--text);
}

/* Theme Toggle */
.theme-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border: 1px solid var(--border);
    border-radius: 8px;
    background: var(--surface);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s;
}

.theme-toggle:hover {
    color: var(--text);
    border-color: var(--text-muted);
}

.moon-icon { display: block; }
.sun-icon { display: none; }

[data-theme="dark"] .moon-icon { display: none; }
[data-theme="dark"] .sun-icon { display: block; }

/* Main Content */
main {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 2rem;
    padding-top: 100px;
}

/* Hero Section */
.hero {
    padding: 4rem 0 6rem;
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 380px;
    gap: 4rem;
    align-items: center;
}

.hero-label {
    display: inline-block;
    font-size: 0.8rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    color: var(--accent);
    margin-bottom: 1rem;
}

.hero h1 {
    font-family: 'Crimson Pro', Georgia, serif;
    font-size: clamp(2.5rem, 5vw, 3.5rem);
    font-weight: 500;
    letter-spacing: -0.02em;
    line-height: 1.15;
    margin-bottom: 1.25rem;
    color: var(--text);
}

.hero-tagline {
    font-size: 1.15rem;
    color: var(--text-secondary);
    max-width: 520px;
    line-height: 1.75;
    margin-bottom: 1.25rem;
}

.hero-highlight {
    font-size: 1.1rem;
    color: var(--text);
    max-width: 520px;
    line-height: 1.7;
    margin-bottom: 2rem;
}

.hero-highlight strong {
    color: var(--accent);
}

.hero-meta {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-bottom: 2rem;
    padding: 1.25rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 12px;
}

.meta-item {
    display: flex;
    gap: 1rem;
    align-items: baseline;
}

.meta-label {
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    color: var(--text-muted);
    min-width: 80px;
}

.meta-value {
    font-size: 0.95rem;
    color: var(--text-secondary);
}

.hero-links {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.25rem;
    border-radius: 8px;
    font-size: 0.9rem;
    font-weight: 500;
    text-decoration: none;
    transition: all 0.2s;
}

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

.btn-primary:hover {
    background: var(--accent-hover);
}

.btn-secondary {
    background: var(--surface);
    color: var(--text-secondary);
    border: 1px solid var(--border);
}

.btn-secondary:hover {
    border-color: var(--text-muted);
    color: var(--text);
}

/* Hero Image */
.hero-image {
    position: relative;
}

.hero-image img {
    width: 100%;
    height: 480px;
    object-fit: cover;
    object-position: center top;
    border-radius: 16px;
    box-shadow: 0 20px 40px var(--shadow);
}

/* Sections */
.section {
    padding: 5rem 0;
    border-top: 1px solid var(--border);
}

.section-header {
    margin-bottom: 2.5rem;
}

.section-header h2 {
    font-family: 'Crimson Pro', Georgia, serif;
    font-size: 2rem;
    font-weight: 500;
    letter-spacing: -0.01em;
    margin-bottom: 0.5rem;
}

.section-subtitle {
    font-size: 1.05rem;
    color: var(--text-secondary);
    max-width: 600px;
    line-height: 1.7;
}

/* Cards */
.cards {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
}

.card {
    padding: 1.75rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 12px;
    transition: all 0.2s;
}

.card:hover {
    box-shadow: 0 8px 24px var(--shadow);
    transform: translateY(-2px);
}

.card-icon {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--accent-light);
    border-radius: 10px;
    margin-bottom: 1.25rem;
    color: var(--accent);
}

.card h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Project Feature */
.project-feature {
    padding: 2rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 16px;
}

.project-badge {
    display: inline-block;
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--accent);
    padding: 0.375rem 0.75rem;
    background: var(--accent-light);
    border-radius: 100px;
    margin-bottom: 1rem;
}

.project-feature h3 {
    font-family: 'Crimson Pro', Georgia, serif;
    font-size: 1.5rem;
    font-weight: 500;
    margin-bottom: 0.75rem;
}

.project-feature p {
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 1.25rem;
    max-width: 600px;
}

.project-desc {
    font-size: 1.1rem;
    margin-bottom: 2rem !important;
}

.project-feature h4 {
    font-size: 0.85rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    color: var(--text-muted);
    margin-bottom: 1rem;
}

.feature-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.feature-list li {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.6;
    padding-left: 1.5rem;
    position: relative;
}

.feature-list li::before {
    content: '•';
    position: absolute;
    left: 0;
    color: var(--accent);
    font-weight: bold;
}

.feature-list li strong {
    color: var(--text);
}

/* Principles */
.principles {
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

.principle {
    display: flex;
    gap: 1rem;
    padding: 1.25rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
    transition: all 0.2s;
}

.principle:hover {
    border-color: var(--accent);
}

.principle-icon {
    color: var(--accent);
    font-weight: 600;
    font-size: 1.1rem;
    flex-shrink: 0;
}

.principle strong {
    display: block;
    font-size: 0.95rem;
    margin-bottom: 0.25rem;
    color: var(--text);
}

.principle p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin: 0;
}

/* Expectations */
.section-intro {
    font-size: 1.05rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.expect-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1rem;
}

.expect-item {
    display: flex;
    gap: 0.75rem;
    padding: 1.25rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

.expect-item strong {
    color: var(--text);
}

.expect-bullet {
    color: var(--accent);
    font-weight: 600;
    flex-shrink: 0;
}

.project-tags {
    display: flex;
    gap: 0.5rem;
}

.project-tags span {
    font-size: 0.75rem;
    font-weight: 500;
    padding: 0.375rem 0.75rem;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 100px;
    color: var(--text-muted);
}

/* Stats */
.stats {
    display: flex;
    gap: 4rem;
    margin-bottom: 2rem;
}

.stat {
    display: flex;
    flex-direction: column;
}

.stat-value {
    font-family: 'Crimson Pro', Georgia, serif;
    font-size: 3rem;
    font-weight: 500;
    color: var(--accent);
    line-height: 1;
    margin-bottom: 0.25rem;
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* Photo Section */
.photo-section {
    padding: 0;
    border: none;
}

.full-photo {
    width: 100%;
    height: 500px;
    object-fit: cover;
    object-position: center 30%;
    border-radius: 20px;
    box-shadow: 0 20px 40px var(--shadow);
}

/* Contact Section */
.contact-section {
    text-align: center;
    padding: 5rem 0;
}

.contact-section .section-header {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.contact-links {
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.contact-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.75rem;
    padding: 1rem 1.5rem;
    background: var(--accent);
    color: white;
    border-radius: 10px;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.2s;
}

.contact-btn:hover {
    background: var(--accent-hover);
}

.contact-btn.secondary {
    background: var(--surface);
    color: var(--text-secondary);
    border: 1px solid var(--border);
}

.contact-btn.secondary:hover {
    border-color: var(--text-muted);
    color: var(--text);
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem;
    border-top: 1px solid var(--border);
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* Research Page */
.research-page {
    padding-top: 120px;
}

.page-hero {
    padding-bottom: 3rem;
}

.page-hero h1 {
    font-family: 'Crimson Pro', Georgia, serif;
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 500;
    letter-spacing: -0.01em;
    margin-bottom: 0.75rem;
}

.page-subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    max-width: 550px;
}

/* Snapshot Grid */
.snapshot-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1rem;
}

.snapshot-item {
    padding: 1.25rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
}

.snapshot-label {
    display: block;
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--text-muted);
    margin-bottom: 0.375rem;
}

.snapshot-value {
    font-size: 0.95rem;
    color: var(--text);
}

/* Timeline */
.timeline {
    position: relative;
    padding-left: 1.5rem;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 4px;
    bottom: 4px;
    width: 2px;
    background: var(--border);
    border-radius: 2px;
}

.timeline-item {
    position: relative;
    padding-bottom: 2rem;
}

.timeline-item:last-child {
    padding-bottom: 0;
}

.timeline-marker {
    position: absolute;
    left: -1.5rem;
    top: 4px;
    width: 10px;
    height: 10px;
    background: var(--accent);
    border-radius: 50%;
    transform: translateX(-4px);
}

.timeline-content {
    padding-left: 1rem;
}

.timeline-period {
    display: inline-block;
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--accent);
    margin-bottom: 0.375rem;
}

.timeline-content h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.timeline-location {
    font-size: 0.85rem;
    color: var(--text-muted);
    display: block;
    margin-bottom: 0.5rem;
}

.timeline-content p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Publications */
.pub-links {
    display: flex;
    gap: 0.75rem;
    margin-bottom: 2.5rem;
}

.pub-category {
    margin-bottom: 2rem;
}

.pub-category h3 {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-muted);
    margin-bottom: 0.75rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border);
}

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

.pub-item {
    display: flex;
    gap: 1.25rem;
    padding: 0.875rem 0;
    border-bottom: 1px solid var(--border);
}

.pub-year {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--accent);
    min-width: 45px;
}

.pub-title {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.5;
}

/* Skills Grid */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
}

.skill-item {
    padding: 1.25rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
}

.skill-item h3 {
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 0.375rem;
}

.skill-item p {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

/* Responsive */
@media (max-width: 900px) {
    .hero-content {
        grid-template-columns: 1fr;
        gap: 3rem;
    }
    
    .hero-image {
        order: -1;
    }
    
    .hero-image img {
        height: 400px;
    }
    
    .cards {
        grid-template-columns: 1fr;
    }
    
    .stats {
        flex-wrap: wrap;
        gap: 2rem;
    }
}

@media (max-width: 600px) {
    .nav {
        padding: 1rem;
    }
    
    .nav-right {
        gap: 1rem;
    }
    
    .nav-links {
        gap: 1rem;
    }
    
    main {
        padding: 0 1rem;
        padding-top: 80px;
    }
    
    .hero {
        padding: 2rem 0 4rem;
    }
    
    .section {
        padding: 3rem 0;
    }
    
    .hero-links {
        flex-direction: column;
    }
    
    .hero-image img {
        height: 350px;
    }
    
    .full-photo {
        height: 300px;
        border-radius: 12px;
    }
    
    .contact-links {
        flex-direction: column;
        align-items: center;
    }
}