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

:root {
    --color-bg: #f4f5f7;
    --color-surface: #ffffff;
    --color-text: #0e2a47;
    --color-text-secondary: #4a5568;
    --color-accent: #00356b;
    --color-accent-light: #286dc0;
    --color-border: #d8dde6;
    --color-highlight: #edf1f7;
    --font-serif: 'Source Serif 4', Georgia, 'Times New Roman', serif;
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --max-width: 960px;
    --nav-height: 64px;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-sans);
    color: var(--color-text);
    background: var(--color-bg);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
}

a {
    color: var(--color-accent);
    text-decoration: none;
    transition: color 0.2s;
}

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

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

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* ========== Navbar ========== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--nav-height);
    background: rgba(244, 245, 247, 0.92);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    z-index: 100;
    transition: box-shadow 0.3s;
}

.navbar.scrolled {
    box-shadow: 0 1px 8px rgba(0, 0, 0, 0.06);
}

.nav-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-name {
    font-family: var(--font-serif);
    font-weight: 600;
    font-size: 1.1rem;
    color: var(--color-text);
    letter-spacing: -0.01em;
}

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

.nav-links {
    list-style: none;
    display: flex;
    gap: 32px;
    align-items: center;
}

.nav-links a {
    font-size: 0.875rem;
    font-weight: 450;
    color: var(--color-text-secondary);
    letter-spacing: 0.01em;
    transition: color 0.2s;
}

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

.nav-cv {
    padding: 6px 16px;
    border: 1.5px solid var(--color-accent);
    border-radius: 6px;
    color: var(--color-accent) !important;
    font-weight: 500 !important;
}

.nav-cv:hover {
    background: var(--color-accent);
    color: #fff !important;
}

/* Mobile nav toggle */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
    flex-direction: column;
    gap: 5px;
}

.nav-toggle span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--color-text);
    border-radius: 2px;
    transition: transform 0.3s, opacity 0.3s;
}

.nav-toggle.active span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

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

.nav-toggle.active span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* ========== Hero / About ========== */
.hero {
    padding-top: calc(var(--nav-height) + 64px);
    padding-bottom: 80px;
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
}

.hero-grid {
    display: grid;
    grid-template-columns: 1fr 280px;
    gap: 60px;
    align-items: center;
}

.hero h1 {
    font-family: var(--font-serif);
    font-size: 2.75rem;
    font-weight: 700;
    line-height: 1.15;
    letter-spacing: -0.02em;
    color: var(--color-text);
    margin-bottom: 8px;
}

.subtitle {
    font-size: 1.2rem;
    font-weight: 400;
    color: var(--color-accent);
    margin-bottom: 2px;
}

.affiliation {
    font-size: 1rem;
    color: var(--color-text-secondary);
    margin-bottom: 24px;
}

.bio {
    font-size: 1rem;
    color: var(--color-text-secondary);
    line-height: 1.75;
    max-width: 540px;
    margin-bottom: 28px;
}

.bio em {
    font-style: italic;
    color: var(--color-text);
}

.hero-links {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

.btn {
    display: inline-block;
    padding: 10px 24px;
    border-radius: 6px;
    font-size: 0.9rem;
    font-weight: 500;
    letter-spacing: 0.01em;
    transition: all 0.2s;
}

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

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

.btn-secondary {
    border: 1.5px solid var(--color-border);
    color: var(--color-text-secondary);
}

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

.hero-photo img {
    width: 100%;
    aspect-ratio: 3/4;
    object-fit: cover;
    border-radius: 12px;
    filter: grayscale(10%);
}

/* ========== Sections ========== */
.section {
    padding: 72px 0;
}

.section-alt {
    background: var(--color-surface);
    border-top: 1px solid var(--color-border);
    border-bottom: 1px solid var(--color-border);
}

.section h2 {
    font-family: var(--font-serif);
    font-size: 1.85rem;
    font-weight: 600;
    letter-spacing: -0.01em;
    margin-bottom: 40px;
    color: var(--color-text);
}

/* ========== Working Papers ========== */
.paper-list {
    display: flex;
    flex-direction: column;
    gap: 28px;
}

.paper {
    padding: 24px 28px;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: 10px;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.paper:hover {
    border-color: var(--color-accent);
    box-shadow: 0 2px 12px rgba(0, 53, 107, 0.08);
}

.paper-title {
    font-family: var(--font-serif);
    font-size: 1.15rem;
    font-weight: 600;
    line-height: 1.4;
    margin-bottom: 6px;
}

.paper-title a {
    color: var(--color-text);
}

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

.paper-authors {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    margin-bottom: 2px;
}

.paper-venue {
    font-size: 0.85rem;
    color: var(--color-accent);
    font-weight: 500;
}

/* ========== Publications ========== */
.pub-category {
    font-family: var(--font-sans);
    font-size: 1.1rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--color-accent);
    margin-bottom: 20px;
    margin-top: 56px;
    padding-top: 40px;
    border-top: 2px solid var(--color-border);
}

.pub-category:first-of-type {
    margin-top: 0;
    padding-top: 0;
    border-top: none;
}

.publication-list {
    list-style: none;
    counter-reset: none;
    display: flex;
    flex-direction: column;
    gap: 20px;
    margin-bottom: 8px;
}

.publication {
    padding: 16px 0;
    border-bottom: 1px solid var(--color-border);
}

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

.pub-title {
    display: block;
    font-family: var(--font-serif);
    font-size: 1.05rem;
    font-weight: 600;
    line-height: 1.45;
    color: var(--color-text);
    margin-bottom: 4px;
    text-decoration: none;
}

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

.pub-meta {
    display: block;
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    line-height: 1.55;
}

.pub-meta em {
    font-style: italic;
    color: var(--color-text);
}

/* ========== Other Writing ========== */
.writing-list {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
}

.writing-item {
    padding: 24px 28px;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: 10px;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.writing-item:hover {
    border-color: var(--color-accent);
    box-shadow: 0 2px 12px rgba(0, 53, 107, 0.08);
}

.writing-venue {
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--color-accent);
    margin-bottom: 8px;
    display: block;
}

.writing-item h3 {
    font-family: var(--font-serif);
    font-size: 1.05rem;
    font-weight: 600;
    line-height: 1.4;
    margin-bottom: 6px;
}

.writing-item h3 a {
    color: var(--color-text);
}

.writing-item h3 a:hover {
    color: var(--color-accent);
}

.writing-date {
    font-size: 0.85rem;
    color: var(--color-text-secondary);
}

/* ========== Footer / Contact ========== */
.footer {
    background: var(--color-accent);
    color: rgba(255, 255, 255, 0.85);
    padding: 64px 0 40px;
}

.footer h2 {
    color: #fff;
    margin-bottom: 32px;
}

.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    margin-bottom: 48px;
}

.contact-info p {
    margin-bottom: 4px;
    font-size: 0.95rem;
}

.contact-info strong {
    color: #fff;
}

.contact-email {
    margin-top: 12px;
}

.contact-email a {
    color: rgba(255, 255, 255, 0.9);
    border-bottom: 1px solid rgba(255, 255, 255, 0.3);
    padding-bottom: 1px;
}

.contact-email a:hover {
    color: #fff;
    border-bottom-color: #fff;
}

.contact-links {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.contact-links a {
    color: rgba(255, 255, 255, 0.75);
    font-size: 0.95rem;
    transition: color 0.2s;
}

.contact-links a:hover {
    color: #fff;
}

.copyright {
    font-size: 0.8rem;
    color: rgba(255, 255, 255, 0.4);
    padding-top: 24px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

/* ========== Responsive ========== */
@media (max-width: 768px) {
    .nav-toggle {
        display: flex;
    }

    .nav-links {
        position: fixed;
        top: var(--nav-height);
        left: 0;
        right: 0;
        background: rgba(250, 250, 249, 0.98);
        backdrop-filter: blur(12px);
        flex-direction: column;
        padding: 24px;
        gap: 20px;
        transform: translateY(-120%);
        transition: transform 0.3s ease;
        border-bottom: 1px solid var(--color-border);
    }

    .nav-links.open {
        transform: translateY(0);
    }

    .hero-grid {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .hero-photo {
        order: -1;
        max-width: 220px;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .writing-list {
        grid-template-columns: 1fr;
    }

    .contact-grid {
        grid-template-columns: 1fr;
        gap: 28px;
    }

    .section {
        padding: 56px 0;
    }

    .hero {
        padding-top: calc(var(--nav-height) + 40px);
        padding-bottom: 56px;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 1.75rem;
    }

    .section h2 {
        font-size: 1.5rem;
    }

    .paper {
        padding: 18px 20px;
    }

    .writing-item {
        padding: 18px 20px;
    }
}