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

:root {
    --text: #000;
    --text-secondary: #000;
    --text-light: #000;
    --bg: #fff;
    --bg-subtle: #f8f8f8;
    --border: #e5e5e5;
    --accent: #2a2a2a;
    --link: #1a1a1a;
    --link-hover: #000;
    --max-width: 900px;
    --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

html { font-size: 24px; scroll-behavior: smooth; scroll-padding-top: 5rem; }

body {
    font-family: var(--font);
    color: var(--text);
    background: var(--bg);
    line-height: 1.65;
    -webkit-font-smoothing: antialiased;
}

a { color: var(--link); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { color: var(--link-hover); }

/* Layout */
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 1.5rem; }

/* Nav */
nav {
    border-bottom: 1px solid var(--border);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    background: var(--bg);
    z-index: 10;
}
nav .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
nav .site-name {
    font-weight: 600;
    font-size: 1.1rem;
    text-decoration: none;
    color: var(--text);
    letter-spacing: -0.01em;
}
nav .nav-links { display: flex; gap: 1.5rem; }
nav .nav-links a {
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 450;
    transition: color 0.15s;
}
nav .nav-links a:hover,
nav .nav-links a.active { color: var(--text); }

/* Nav dropdown */
.nav-dropdown { position: relative; display: flex; align-items: center; }
.nav-dropdown-toggle {
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 450;
    transition: color 0.15s;
    cursor: pointer;
    padding-bottom: 1rem;
}
.nav-dropdown-toggle:hover,
.nav-dropdown-toggle.active { color: var(--text); }
.nav-dropdown-menu {
    display: none;
    position: absolute;
    top: 100%;
    right: 0;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 0.4rem 0;
    min-width: auto;
    white-space: nowrap;
    box-shadow: 0 4px 12px rgba(0,0,0,0.08);
    z-index: 20;
}
.nav-dropdown:hover .nav-dropdown-menu { display: block; }
.nav-dropdown-menu a {
    display: block;
    padding: 0.45rem 1rem;
    font-size: 0.85rem;
    color: var(--text-secondary);
    text-decoration: none;
    transition: background 0.1s, color 0.1s;
}
.nav-dropdown-menu a:hover {
    background: var(--bg-subtle);
    color: var(--text);
}

/* Hero video */
.hero-video {
    padding: 2rem 0 0;
}

/* Hero */
.hero {
    padding: 2rem 0 3rem;
}
.hero-top {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1.25rem;
    margin-bottom: 1.25rem;
}
.hero-image {
    width: 210px;
    height: 210px;
    border-radius: 50%;
    object-fit: cover;
    flex-shrink: 0;
    margin-right: 3rem;
}
.hero-content h1 {
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: 1rem;
}
.hero-roles {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}
.hero-role-title {
    display: block;
    font-size: 1rem;
    font-weight: 500;
    color: var(--text);
}
.hero-role-place {
    display: block;
    font-size: 0.9rem;
    font-style: italic;
    color: var(--text-secondary);
}
.hero-bio {
    font-size: 0.95rem;
    color: var(--text);
    line-height: 1.7;
    margin-bottom: 1rem;
}
.social-links {
    display: flex;
    justify-content: space-between;
    margin-top: 0.75rem;
}
.social-link {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    font-size: 0.85rem;
    text-decoration: none;
    transition: opacity 0.15s;
}
.social-link:hover { opacity: 0.7; }
.social-link svg { width: 18px; height: 18px; }
.social-link { color: var(--text); }
.social-link.x svg { color: #000; }
.social-link.scholar svg { color: #4285F4; }
.social-link.linkedin svg { color: #0A66C2; }
.social-link.youtube svg { color: #FF0000; }
.social-link.email svg { color: var(--text-light); }

/* Sections */
.section {
    padding: 2.5rem 0;
    border-top: 1px solid var(--border);
}
.section-title {
    font-size: 1.25rem;
    font-weight: 650;
    letter-spacing: -0.01em;
    margin-bottom: 1.5rem;
}

/* Research theme cards (home page) */
.theme-cards { display: flex; flex-direction: column; gap: 1.25rem; }
.theme-card {
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 1.5rem;
    text-decoration: none;
    color: var(--text);
    transition: border-color 0.15s, background 0.15s;
    display: block;
}
.theme-card:hover {
    border-color: #ccc;
    background: var(--bg-subtle);
}
.theme-card h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    letter-spacing: -0.01em;
}
.theme-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
}
.theme-card .paper-count {
    font-size: 0.8rem;
    color: var(--text-light);
    margin-top: 0.75rem;
}

/* Video */
.video-container {
    position: relative;
    padding-bottom: 56.25%;
    height: 0;
    overflow: hidden;
    border-radius: 6px;
    margin-top: 0.75rem;
}
.video-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: none;
}
.video-placeholder {
    background: var(--bg-subtle);
    border: 1px dashed var(--border);
    border-radius: 6px;
    padding: 3rem 1.5rem;
    text-align: center;
    color: var(--text-light);
    font-size: 0.9rem;
    margin-top: 0.75rem;
}

/* Commentary */
.commentary-post {
    margin-bottom: 2rem;
    display: flex;
    flex-direction: column;
    align-items: center;
}
.commentary-post:last-of-type { margin-bottom: 0; }
.commentary-link {
    display: inline-block;
    margin-top: 0.4rem;
    font-size: 0.85rem;
    font-weight: 500;
}
.commentary-header {
    font-size: 0.8rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    text-align: center;
}

/* Podcasts */
.podcast { margin-bottom: 1.25rem; }
.podcast:last-child { margin-bottom: 0; }
.podcast h3 {
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    text-align: center;
}
.podcast p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 0.35rem;
}
.podcast-link {
    font-size: 0.85rem;
    font-weight: 500;
}

/* Compact info lists (affiliations, awards) */
.info-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}
.info-block h3 {
    font-size: 0.85rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--text-light);
    margin-bottom: 0.6rem;
}
.info-block ul {
    list-style: none;
    font-size: 0.88rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* Research page */
.research-intro {
    font-size: 0.95rem;
    line-height: 1.7;
    padding: 1.5rem 0 0;
}
.research-nav {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 0.5rem;
    margin-bottom: 2rem;
    padding: 1.5rem 0 0;
}
.research-nav a {
    font-size: 0.85rem;
    color: #000;
    text-decoration: none;
    padding: 0.4rem 0.9rem;
    background: #fff;
    border: 1px solid #000;
    border-radius: 4px;
    transition: all 0.15s;
}
.research-nav a:hover {
    background: #000;
    color: #fff;
}

.research-section { padding: 2rem 0; border-top: 1px solid var(--border); }
.research-section:first-of-type { border-top: none; }
.research-section h2 {
    font-size: 1.15rem;
    font-weight: 650;
    letter-spacing: -0.01em;
    margin-bottom: 0.75rem;
}
.research-section .section-description {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.65;
    margin-bottom: 1.5rem;
}

/* Paper listings */
.paper {
    padding: 1rem 0;
    border-bottom: 1px solid var(--border);
}
.paper:last-child { border-bottom: none; }
.paper-header {
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 1rem;
}
.paper-header:hover .paper-title { color: var(--text-secondary); }
.paper-title {
    font-size: 0.95rem;
    font-weight: 600;
    line-height: 1.45;
    transition: color 0.15s;
}
.paper-meta {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: 0.2rem;
    line-height: 1.5;
}
.paper-venue {
    font-style: italic;
}
.paper-links {
    margin-top: 0.35rem;
    display: flex;
    gap: 0.75rem;
}
.paper-links a {
    font-size: 0.75rem;
    font-weight: 500;
    color: #fff;
    text-decoration: none;
    background: #000;
    padding: 0.2rem 0.6rem;
    border-radius: 3px;
    transition: opacity 0.15s;
}
.paper-links a:hover {
    opacity: 0.75;
}
.paper-toggle {
    flex-shrink: 0;
    width: 20px;
    height: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-light);
    font-size: 1.1rem;
    transition: transform 0.2s;
    margin-top: 0.1rem;
}
.paper.expanded .paper-toggle { transform: rotate(45deg); }
.paper-summary {
    display: none;
    font-size: 0.82rem;
    color: var(--text-secondary);
    line-height: 1.7;
    padding: 0.75rem 1rem;
    border-left: 2px solid var(--border);
    background: #f8f8f8;
    border-radius: 0 4px 4px 0;
    margin-top: 0.5rem;
}
.paper.expanded .paper-summary { display: block; }

/* Working paper badge */
.badge {
    display: inline-block;
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--text-light);
    border: 1px solid var(--border);
    border-radius: 3px;
    padding: 0.1rem 0.4rem;
    margin-left: 0.5rem;
    vertical-align: middle;
}

/* Footer */
footer {
    border-top: 1px solid var(--border);
    padding: 1.5rem 0;
    text-align: center;
    font-size: 0.8rem;
    color: var(--text-light);
    display: flex;
    align-items: center;
    justify-content: center;
}
footer .container {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.3rem;
}
.footer-icon {
    display: inline-flex;
    align-items: center;
    text-decoration: none;
    transition: opacity 0.15s;
}
.footer-icon:hover { opacity: 0.7; }
.footer-icon.x { color: #000; }
.footer-icon.linkedin { color: #0A66C2; }

/* Responsive */
@media (max-width: 640px) {
    .hero-top {
        flex-direction: column-reverse;
        align-items: center;
        text-align: center;
    }
    .hero-bio { text-align: center; }
    .hero-image { width: 120px; height: 120px; }
    .social-links { justify-content: center; }
    .info-grid { grid-template-columns: 1fr; gap: 1rem; }
    .research-nav { gap: 0.35rem; }
    nav .nav-links { gap: 1rem; }
}