/* ==========================================================================
   Design tokens
   ========================================================================== */
:root {
  --color-bg: #FAFAFA;
  --color-fg: #09090B;
  --color-primary: #18181B;
  --color-secondary: #3F3F46;
  --color-muted-bg: #E8ECF0;
  --color-border: #E4E4E7;
  --color-accent: #1D4ED8;
  --color-inverse-bg: #09090B;
  --color-inverse-fg: #FAFAFA;
  --color-inverse-border: rgba(250, 250, 250, 0.14);

  --font-display: "Playfair Display", "Source Serif 4", Georgia, serif;
  --font-body: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;

  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-5: 48px;
  --space-6: 64px;
  --space-7: 96px;
  --space-8: 128px;

  --container: 1180px;
  --radius-sm: 2px;
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --dur-fast: 200ms;
  --dur-base: 400ms;
  --dur-slow: 600ms;
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #0C0C0D;
    --color-fg: #F4F4F5;
    --color-primary: #F4F4F5;
    --color-secondary: #A1A1AA;
    --color-muted-bg: #17171A;
    --color-border: #232327;
    --color-inverse-bg: #F4F4F5;
    --color-inverse-fg: #0C0C0D;
    --color-inverse-border: rgba(9, 9, 11, 0.12);
  }
}

/* ==========================================================================
   Reset
   ========================================================================== */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-fg);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; margin: 0; padding: 0; }
h1, h2, h3, h4, blockquote, p { margin: 0; }
button { font: inherit; color: inherit; background: none; border: none; cursor: pointer; }

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--color-fg);
  color: var(--color-bg);
  padding: 12px 20px;
  z-index: 1000;
}
.skip-link:focus {
  left: var(--space-2);
  top: var(--space-2);
}

:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
}

.noise {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 999;
  opacity: 0.025;
  mix-blend-mode: overlay;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='120' height='120'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

/* ==========================================================================
   Reveal animation
   ========================================================================== */
.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity var(--dur-slow) var(--ease-out), transform var(--dur-slow) var(--ease-out);
}
.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
  * {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}

/* ==========================================================================
   Layout helpers
   ========================================================================== */
.section-inner {
  max-width: var(--container);
  margin: 0 auto;
  padding: var(--space-7) var(--space-3);
}
.section-kicker {
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-secondary);
  margin-bottom: var(--space-2);
}
.section-title {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(28px, 4vw, 42px);
  line-height: 1.2;
  max-width: 18ch;
  margin-bottom: var(--space-3);
}
.section-lead {
  font-size: 18px;
  color: var(--color-secondary);
  max-width: 62ch;
  margin-bottom: var(--space-5);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 15px 28px;
  font-size: 15px;
  font-weight: 600;
  border-radius: 999px;
  cursor: pointer;
  transition: background var(--dur-fast) var(--ease-out), color var(--dur-fast) var(--ease-out), transform var(--dur-fast) var(--ease-out), border-color var(--dur-fast) var(--ease-out);
  border: 1px solid transparent;
  min-height: 44px;
}
.btn-primary {
  background: var(--color-primary);
  color: var(--color-bg);
}
.btn-primary:hover { transform: translateY(-2px); }
.btn-ghost {
  background: transparent;
  color: var(--color-fg);
  border-color: var(--color-border);
}
.btn-ghost:hover {
  background: var(--color-primary);
  color: var(--color-bg);
  border-color: var(--color-primary);
  transform: translateY(-2px);
}

/* ==========================================================================
   Header / Nav
   ========================================================================== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: color-mix(in srgb, var(--color-bg) 82%, transparent);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--dur-base) var(--ease-out), box-shadow var(--dur-base) var(--ease-out);
}
.site-header.is-scrolled {
  border-bottom-color: var(--color-border);
}
.header-inner {
  max-width: var(--container);
  margin: 0 auto;
  padding: 18px var(--space-3);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
}
.brand {
  display: flex;
  align-items: center;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 18px;
  letter-spacing: 0.01em;
  color: var(--color-fg);
}
.brand-suffix { color: var(--color-secondary); font-style: italic; }

.main-nav {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  font-size: 14.5px;
  font-weight: 500;
}
.main-nav a {
  position: relative;
  padding: 6px 0;
  color: var(--color-secondary);
  transition: color var(--dur-fast) var(--ease-out);
}
.main-nav a:hover { color: var(--color-fg); }
.main-nav a::after {
  content: "";
  position: absolute;
  left: 0; right: 100%;
  bottom: 0;
  height: 1px;
  background: var(--color-fg);
  transition: right var(--dur-base) var(--ease-out);
}
.main-nav a:hover::after { right: 0; }

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  cursor: pointer;
}
.nav-toggle span {
  display: block;
  width: 22px;
  height: 1.6px;
  background: var(--color-fg);
  transition: transform var(--dur-fast) var(--ease-out), opacity var(--dur-fast) var(--ease-out);
  margin: 0 auto;
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(6.6px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-6.6px) rotate(-45deg); }

.mobile-nav {
  display: none;
  flex-direction: column;
  padding: 0 var(--space-3);
  gap: 2px;
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--dur-base) var(--ease-out), padding-bottom var(--dur-base) var(--ease-out);
}
.mobile-nav.is-open { max-height: 400px; padding-bottom: var(--space-3); }
.mobile-nav a {
  padding: 14px 4px;
  font-size: 16px;
  border-top: 1px solid var(--color-border);
  color: var(--color-fg);
}

/* ==========================================================================
   Hero
   ========================================================================== */
.hero {
  position: relative;
  padding: 160px var(--space-3) var(--space-6);
  max-width: var(--container);
  margin: 0 auto;
}
.hero-inner {
  display: grid;
  grid-template-columns: 1.3fr 0.9fr;
  gap: var(--space-6);
  align-items: center;
}
.eyebrow {
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-secondary);
  margin-bottom: var(--space-3);
}
.hero-title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(48px, 8vw, 96px);
  line-height: 0.98;
  letter-spacing: -0.01em;
  margin-bottom: var(--space-3);
}
.hero-title .line { display: block; }
.hero-title em { font-style: italic; font-weight: 500; color: var(--color-secondary); }
.hero-subtitle {
  font-size: 19px;
  line-height: 1.6;
  color: var(--color-secondary);
  max-width: 46ch;
  margin-bottom: var(--space-4);
}
.hero-actions {
  display: flex;
  gap: var(--space-2);
  flex-wrap: wrap;
}

.hero-visual { display: flex; flex-direction: column; align-items: center; }
.portrait-frame {
  width: 100%;
  aspect-ratio: 4 / 5;
  background: var(--color-primary);
  border-radius: 4px;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  position: relative;
  overflow: hidden;
}
.portrait-glow {
  position: absolute;
  left: 50%;
  top: 38%;
  width: 85%;
  aspect-ratio: 1;
  transform: translate(-50%, -50%);
  background: radial-gradient(circle, rgba(250, 250, 250, 0.16) 0%, transparent 68%);
  pointer-events: none;
}
.portrait-photo {
  position: relative;
  z-index: 1;
  width: 88%;
  height: auto;
  object-fit: contain;
}

/* ==========================================================================
   Credentials marquee
   ========================================================================== */
.credentials {
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-3) 0;
  overflow: hidden;
}
.marquee { width: 100%; overflow: hidden; -webkit-mask-image: linear-gradient(90deg, transparent, #000 8%, #000 92%, transparent); mask-image: linear-gradient(90deg, transparent, #000 8%, #000 92%, transparent); }
.marquee-track {
  display: flex;
  gap: var(--space-2);
  width: max-content;
  animation: marquee 32s linear infinite;
}
@media (prefers-reduced-motion: reduce) {
  .marquee-track { animation: none; }
}
@keyframes marquee {
  from { transform: translateX(0); }
  to { transform: translateX(-50%); }
}
.pill {
  white-space: nowrap;
  padding: 10px 22px;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  font-size: 14px;
  color: var(--color-secondary);
}

/* ==========================================================================
   Stats
   ========================================================================== */
.stats { padding: var(--space-6) var(--space-3); max-width: var(--container); margin: 0 auto; }
.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-4);
}
.stat { display: flex; flex-direction: column; gap: 4px; }
.stat-value { display: inline-flex; align-items: baseline; }
.stat-number {
  font-family: var(--font-display);
  font-size: clamp(36px, 4.5vw, 52px);
  font-weight: 700;
  line-height: 1;
}
.stat-plus {
  font-family: var(--font-display);
  font-size: clamp(28px, 3.5vw, 38px);
  font-weight: 700;
}
.stat-label {
  font-size: 14px;
  color: var(--color-secondary);
  max-width: 20ch;
}

/* ==========================================================================
   About
   ========================================================================== */
.about { background: var(--color-muted-bg); }
.pull-quote {
  font-family: var(--font-display);
  font-style: italic;
  font-weight: 500;
  font-size: clamp(24px, 3.6vw, 36px);
  line-height: 1.35;
  max-width: 22ch;
  margin-bottom: var(--space-6);
}
.about-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  gap: var(--space-6);
}
.about-text p { color: var(--color-secondary); font-size: 17px; margin-bottom: var(--space-3); }
.about-text p:last-child { margin-bottom: 0; }
.about-interests h3 {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 600;
  margin-bottom: var(--space-2);
}
.tag-list { display: flex; flex-direction: column; gap: 10px; }
.tag-list li {
  padding: 12px 16px;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 6px;
  font-size: 14.5px;
}

/* ==========================================================================
   Timeline
   ========================================================================== */
.subsection-title {
  font-family: var(--font-display);
  font-size: 22px;
  font-weight: 600;
  margin: var(--space-6) 0 var(--space-4);
}
.timeline { position: relative; }
.timeline-line {
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 1px;
  background: var(--color-border);
}
.timeline-line-fill {
  position: absolute;
  left: 0; top: 0;
  width: 100%; height: 0%;
  background: var(--color-fg);
  transition: height 1.1s var(--ease-out);
}
.timeline-row {
  position: relative;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: var(--space-3);
  align-items: baseline;
  padding: var(--space-3) 0 var(--space-3) var(--space-4);
  border-bottom: 1px solid var(--color-border);
}
.timeline-row:first-child { padding-top: 0; }
.timeline-row::before {
  content: "";
  position: absolute;
  left: -4px;
  top: var(--space-3);
  width: 9px; height: 9px;
  border-radius: 50%;
  background: var(--color-bg);
  border: 1px solid var(--color-fg);
}
.timeline-content h3 {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 600;
  margin-bottom: 4px;
}
.timeline-content p { color: var(--color-secondary); font-size: 15px; max-width: 60ch; }
.timeline-year {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-secondary);
  white-space: nowrap;
  letter-spacing: 0.02em;
}

/* ==========================================================================
   Research
   ========================================================================== */
.research-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-3);
}
.research-card {
  padding: var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  transition: transform var(--dur-base) var(--ease-out), border-color var(--dur-base) var(--ease-out), background var(--dur-base) var(--ease-out);
}
.research-card:hover {
  transform: translateY(-4px);
  border-color: var(--color-fg);
}
.research-year {
  display: inline-block;
  font-size: 13px;
  font-weight: 600;
  color: var(--color-secondary);
  margin-bottom: var(--space-2);
}
.research-card h3 {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 600;
  margin-bottom: 6px;
}
.research-role {
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-accent);
  margin-bottom: 10px;
}
.research-card p:not(.research-role) { color: var(--color-secondary); font-size: 15px; }
.research-footnote {
  margin-top: var(--space-4);
  font-size: 14px;
  color: var(--color-secondary);
  max-width: 65ch;
}

/* ==========================================================================
   Publications
   ========================================================================== */
.pub-tabs {
  display: flex;
  gap: 8px;
  margin-bottom: var(--space-4);
  flex-wrap: wrap;
}
.pub-tab {
  padding: 12px 22px;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  font-size: 14.5px;
  font-weight: 600;
  color: var(--color-secondary);
  transition: background var(--dur-fast) var(--ease-out), color var(--dur-fast) var(--ease-out), border-color var(--dur-fast) var(--ease-out);
  min-height: 44px;
}
.pub-tab:hover { border-color: var(--color-fg); color: var(--color-fg); }
.pub-tab.is-active {
  background: var(--color-primary);
  color: var(--color-bg);
  border-color: var(--color-primary);
}
.pub-list { display: none; flex-direction: column; }
.pub-list.is-active { display: flex; }
.pub-item {
  display: grid;
  grid-template-columns: 64px 1fr;
  gap: var(--space-3);
  padding: var(--space-3) 0;
  border-bottom: 1px solid var(--color-border);
}
.pub-item:first-child { padding-top: 0; }
.pub-year { font-size: 14px; font-weight: 600; color: var(--color-secondary); }
.pub-title { font-size: 17px; font-weight: 600; line-height: 1.4; margin-bottom: 6px; }
.pub-title a { border-bottom: 1px solid var(--color-border); transition: border-color var(--dur-fast) var(--ease-out); }
.pub-title a:hover { border-color: var(--color-fg); }
.pub-meta { font-size: 14px; color: var(--color-secondary); line-height: 1.5; }

/* ==========================================================================
   Presentations
   ========================================================================== */
.presentations-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-3);
}
.presentation-card {
  padding: var(--space-3);
  background: var(--color-muted-bg);
  border-radius: 8px;
  transition: transform var(--dur-base) var(--ease-out);
}
.presentation-card:hover { transform: translateY(-4px); }
.presentation-card h3 {
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 600;
  line-height: 1.35;
  margin: 8px 0 8px;
}
.presentation-card p { font-size: 14px; color: var(--color-secondary); }

/* ==========================================================================
   Footer
   ========================================================================== */
.site-footer {
  background: var(--color-inverse-bg);
  color: var(--color-inverse-fg);
}
.footer-inner { max-width: var(--container); margin: 0 auto; padding: var(--space-7) var(--space-3) var(--space-4); }
.site-footer .section-kicker { color: rgba(250,250,250,0.55); }
@media (prefers-color-scheme: dark) {
  .site-footer .section-kicker { color: rgba(9,9,11,0.55); }
}
.footer-title {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(32px, 5vw, 52px);
  margin-bottom: var(--space-3);
}
.footer-lead {
  font-size: 17px;
  max-width: 56ch;
  opacity: 0.72;
  margin-bottom: var(--space-6);
}
.footer-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-4);
  padding-top: var(--space-5);
  border-top: 1px solid var(--color-inverse-border);
}
.footer-grid h3 {
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  opacity: 0.55;
  margin-bottom: 10px;
}
.footer-grid p { font-size: 15px; line-height: 1.6; }
.placeholder-note { opacity: 0.5; font-style: italic; }
.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: var(--space-6);
  padding-top: var(--space-3);
  border-top: 1px solid var(--color-inverse-border);
  font-size: 13.5px;
  opacity: 0.6;
}
.footer-bottom a { transition: opacity var(--dur-fast) var(--ease-out); }
.footer-bottom a:hover { opacity: 1; }

/* ==========================================================================
   Responsive
   ========================================================================== */
@media (max-width: 1024px) {
  .about-grid { grid-template-columns: 1fr; }
  .research-grid, .presentations-grid { grid-template-columns: repeat(2, 1fr); }
  .stats-grid { grid-template-columns: repeat(2, 1fr); gap: var(--space-5); }
  .footer-grid { grid-template-columns: 1fr; gap: var(--space-3); }
}

@media (max-width: 860px) {
  .main-nav { display: none; }
  .nav-toggle { display: flex; }
  .mobile-nav { display: flex; }

  .hero { padding: 128px var(--space-2) var(--space-5); }
  .hero-inner { grid-template-columns: 1fr; gap: var(--space-4); }
  .hero-visual { order: -1; max-width: 260px; margin: 0 auto; }

  .section-inner { padding: var(--space-6) var(--space-2); }
  .research-grid, .presentations-grid { grid-template-columns: 1fr; }

  .timeline-row { grid-template-columns: 1fr; gap: 4px; }
  .timeline-year { order: -1; }

  .pub-item { grid-template-columns: 1fr; gap: 6px; }
}

@media (max-width: 480px) {
  .stats-grid { grid-template-columns: 1fr 1fr; }
  .hero-actions { flex-direction: column; align-items: stretch; }
  .pub-tabs { gap: 6px; }
  .pub-tab { padding: 10px 16px; font-size: 13.5px; }
}