:root {
  --bg: #ffffff;
  --bg-alt: #f6f7f9;
  --text: #1a1d23;
  --text-muted: #5b6270;
  --border: #e4e7ec;
  --accent: #2a5bd7;
  --accent2: #9b4ddb;
  --accent-soft: #eaf0ff;
  --card-bg: #ffffff;
  --shadow: 0 1px 3px rgba(20, 24, 33, 0.06), 0 8px 24px rgba(20, 24, 33, 0.05);
  --shadow-lg: 0 20px 45px rgba(42, 91, 215, 0.16);
  --radius: 14px;
  --maxw: 980px;
  --font: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", Consolas, monospace;
  --dot: rgba(20, 24, 33, 0.07);
}

:root[data-theme="dark"] {
  --bg: #0f1115;
  --bg-alt: #161920;
  --text: #e8eaed;
  --text-muted: #9aa1ae;
  --border: #272b33;
  --accent: #6e9cff;
  --accent2: #c792ff;
  --accent-soft: #19233d;
  --card-bg: #161920;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.3), 0 8px 24px rgba(0, 0, 0, 0.35);
  --shadow-lg: 0 20px 45px rgba(110, 156, 255, 0.18);
  --dot: rgba(255, 255, 255, 0.07);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  transition: background 0.25s ease, color 0.25s ease;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

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

/* ---------- Nav ---------- */
header.site-nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 14px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.nav-name {
  font-weight: 700;
  font-size: 1.02rem;
  letter-spacing: -0.01em;
  white-space: nowrap;
}

nav.nav-links {
  display: flex;
  gap: 4px;
  flex-wrap: wrap;
}

nav.nav-links a {
  position: relative;
  color: var(--text-muted);
  font-size: 0.92rem;
  padding: 6px 10px;
  border-radius: 8px;
  transition: background 0.15s, color 0.15s;
}

nav.nav-links a:hover,
nav.nav-links a.active {
  color: var(--text);
  background: var(--bg-alt);
  text-decoration: none;
}

nav.nav-links a.active::after {
  content: "";
  position: absolute;
  left: 10px;
  right: 10px;
  bottom: 2px;
  height: 2px;
  border-radius: 2px;
  background: linear-gradient(90deg, var(--accent), var(--accent2));
}

.theme-toggle {
  border: 1px solid var(--border);
  background: var(--bg-alt);
  color: var(--text);
  border-radius: 8px;
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  flex-shrink: 0;
}
.theme-toggle:hover { border-color: var(--accent); }

/* ---------- Hero ---------- */
.hero {
  padding: 96px 0 64px;
  position: relative;
  overflow: hidden;
  background-image:
    radial-gradient(circle at 1px 1px, var(--dot) 1px, transparent 0);
  background-size: 22px 22px;
}

.hero::before,
.hero::after {
  content: "";
  position: absolute;
  width: 480px;
  height: 480px;
  border-radius: 50%;
  filter: blur(90px);
  opacity: 0.28;
  z-index: 0;
  pointer-events: none;
  animation: blobfloat 16s ease-in-out infinite alternate;
}
.hero::before {
  background: var(--accent);
  top: -220px;
  left: -160px;
}
.hero::after {
  background: var(--accent2);
  bottom: -220px;
  right: -160px;
  animation-delay: -8s;
}

@keyframes blobfloat {
  0%   { transform: translate(0, 0) scale(1); }
  50%  { transform: translate(40px, 30px) scale(1.12); }
  100% { transform: translate(-20px, -20px) scale(0.96); }
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.3fr 0.7fr;
  gap: 40px;
  align-items: center;
  position: relative;
  z-index: 1;
}

.hero h1 {
  font-size: clamp(2.2rem, 4.6vw, 3.1rem);
  margin: 0 0 8px;
  letter-spacing: -0.02em;
  background: linear-gradient(100deg, var(--text) 30%, var(--accent) 65%, var(--accent2) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  animation: heroin 0.7s ease both;
}

.hero .role {
  font-size: 1.15rem;
  color: var(--text-muted);
  margin: 0 0 20px;
  min-height: 1.6em;
  animation: heroin 0.7s ease 0.08s both;
}

.hero .role .cursor {
  display: inline-block;
  width: 2px;
  height: 1.05em;
  background: var(--accent);
  margin-left: 2px;
  vertical-align: -0.15em;
  animation: blink 1s step-end infinite;
}

@keyframes blink { 50% { opacity: 0; } }

@keyframes heroin {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

.hero .lede { animation: heroin 0.7s ease 0.16s both; }
.hero-links { animation: heroin 0.7s ease 0.24s both; }
.metrics-row { animation: heroin 0.7s ease 0.32s both; }
.hero-photo { animation: heroin 0.8s ease 0.2s both; }

.hero .lede {
  font-size: 1.02rem;
  color: var(--text-muted);
  max-width: 560px;
}

.hero-photo {
  width: 100%;
  max-width: 220px;
  margin-left: auto;
  border-radius: 50%;
  border: 3px solid var(--bg);
  box-shadow: var(--shadow-lg);
  display: block;
  transition: transform 0.35s ease;
}
.hero-photo:hover { transform: scale(1.04) rotate(1deg); }

.hero-links {
  display: flex;
  gap: 10px;
  margin-top: 24px;
  flex-wrap: wrap;
}

.pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  border-radius: 999px;
  border: 1px solid var(--border);
  font-size: 0.88rem;
  color: var(--text);
  background: var(--bg-alt);
  transition: border-color 0.18s, background 0.18s, transform 0.18s;
}
.pill:hover {
  border-color: var(--accent);
  background: var(--accent-soft);
  text-decoration: none;
  transform: translateY(-2px);
}

.metrics-row {
  display: flex;
  gap: 28px;
  margin-top: 28px;
  flex-wrap: wrap;
}
.metric { text-align: left; }
.metric .num {
  font-size: 1.6rem;
  font-weight: 700;
  display: block;
  letter-spacing: -0.02em;
  background: linear-gradient(100deg, var(--accent), var(--accent2));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.metric .label { font-size: 0.8rem; color: var(--text-muted); }

/* ---------- Sections ---------- */
section { padding: 56px 0; border-top: 1px solid var(--border); }
section:first-of-type { border-top: none; }

h2.section-title {
  font-size: 1.5rem;
  margin: 0 0 6px;
  letter-spacing: -0.01em;
}
.section-kicker {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent);
  font-weight: 600;
  margin-bottom: 6px;
}
.section-intro { color: var(--text-muted); margin-bottom: 28px; max-width: 680px; }

/* reveal-on-scroll */
.reveal { opacity: 0; transform: translateY(16px); transition: opacity 0.5s ease, transform 0.5s ease; }
.reveal.in { opacity: 1; transform: translateY(0); }

.research-grid .research-card,
.project-grid .project-card {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.45s ease, transform 0.45s ease;
}
.reveal.in .research-grid .research-card,
.reveal.in .project-grid .project-card {
  opacity: 1;
  transform: translateY(0);
}
.research-grid .research-card:nth-child(1), .project-grid .project-card:nth-child(1) { transition-delay: 0.02s; }
.research-grid .research-card:nth-child(2), .project-grid .project-card:nth-child(2) { transition-delay: 0.08s; }
.research-grid .research-card:nth-child(3), .project-grid .project-card:nth-child(3) { transition-delay: 0.14s; }
.research-grid .research-card:nth-child(4), .project-grid .project-card:nth-child(4) { transition-delay: 0.2s; }
.research-grid .research-card:nth-child(5) { transition-delay: 0.26s; }
.research-grid .research-card:nth-child(6) { transition-delay: 0.32s; }
.research-grid .research-card:nth-child(7) { transition-delay: 0.38s; }
.project-grid .project-card:nth-child(5) { transition-delay: 0.26s; }
.project-grid .project-card:nth-child(6) { transition-delay: 0.32s; }
.project-grid .project-card:nth-child(7) { transition-delay: 0.38s; }
.project-grid .project-card:nth-child(8) { transition-delay: 0.44s; }
.project-grid .project-card:nth-child(9) { transition-delay: 0.5s; }

/* ---------- Research ---------- */
.research-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
}
.research-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}
.research-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--accent);
}
.research-card h3 { margin: 0 0 8px; font-size: 1.02rem; }
.research-card p { margin: 0; color: var(--text-muted); font-size: 0.92rem; }

/* ---------- Projects ---------- */
.filter-row {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 24px;
}
.filter-btn {
  border: 1px solid var(--border);
  background: var(--bg-alt);
  color: var(--text-muted);
  border-radius: 999px;
  padding: 6px 14px;
  font-size: 0.85rem;
  cursor: pointer;
}
.filter-btn { transition: transform 0.15s ease, background 0.15s ease, color 0.15s ease, border-color 0.15s ease; }
.filter-btn:hover { border-color: var(--accent); color: var(--text); transform: translateY(-1px); }
.filter-btn.active {
  color: #fff;
  background: linear-gradient(100deg, var(--accent), var(--accent2));
  border-color: transparent;
}

.project-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 18px;
}

.project-card {
  position: relative;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow);
  transition: transform 0.22s ease, border-color 0.22s ease, box-shadow 0.22s ease;
  overflow: hidden;
}
.project-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent), var(--accent2));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.25s ease;
}
.project-card:hover {
  transform: translateY(-5px);
  border-color: var(--accent);
  box-shadow: var(--shadow-lg);
}
.project-card:hover::before { transform: scaleX(1); }

.project-card h3 { margin: 0 0 8px; font-size: 1.05rem; }
.project-card p.desc { color: var(--text-muted); font-size: 0.9rem; flex-grow: 1; margin: 0 0 14px; }

.tag-row { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 14px; }
.tag {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  background: var(--accent-soft);
  color: var(--accent);
  padding: 3px 8px;
  border-radius: 6px;
}

.card-links { display: flex; gap: 12px; flex-wrap: wrap; font-size: 0.86rem; margin-top: auto; }
.card-links a { font-weight: 600; }

/* ---------- Publications ---------- */
.pub-group { margin-bottom: 28px; }
.pub-group h3 { font-size: 1rem; color: var(--text-muted); font-weight: 600; margin-bottom: 14px; text-transform: uppercase; letter-spacing: 0.04em; font-size: 0.82rem; }
.pub-item {
  padding: 14px 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.95rem;
}
.pub-item:last-child { border-bottom: none; }
.pub-item .pub-title { font-weight: 600; }
.pub-item .pub-meta { color: var(--text-muted); font-size: 0.86rem; margin-top: 2px; }

/* ---------- Timeline (education/honors/teaching) ---------- */
.timeline { border-left: 2px solid var(--border); padding-left: 20px; margin-left: 4px; }
.timeline-item { position: relative; padding-bottom: 22px; }
.timeline-item:last-child { padding-bottom: 0; }
.timeline-item::before {
  content: "";
  position: absolute;
  left: -26px;
  top: 4px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--accent);
}
.timeline-item h3 { margin: 0 0 2px; font-size: 0.98rem; }
.timeline-item .meta { color: var(--text-muted); font-size: 0.85rem; margin-bottom: 4px; }
.timeline-item p { margin: 0; font-size: 0.9rem; color: var(--text-muted); }

/* ---------- Two-col ---------- */
.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 36px; }

/* ---------- Footer ---------- */
footer {
  padding: 36px 0 48px;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}
footer a { color: var(--text-muted); }

.back-to-top {
  position: fixed;
  bottom: 24px;
  right: 24px;
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  border: none;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease;
  box-shadow: var(--shadow);
  z-index: 40;
}
.back-to-top.show { opacity: 1; pointer-events: auto; }

.menu-toggle {
  display: none;
  border: 1px solid var(--border);
  background: var(--bg-alt);
  color: var(--text);
  border-radius: 8px;
  width: 36px;
  height: 36px;
  align-items: center;
  justify-content: center;
  cursor: pointer;
}

@media (max-width: 720px) {
  .hero-grid { grid-template-columns: 1fr; }
  .hero-photo { max-width: 140px; margin: 0 auto; }
  .two-col { grid-template-columns: 1fr; gap: 0; }
  .menu-toggle { display: flex; }
  nav.nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    padding: 8px 24px 14px;
  }
  nav.nav-links.open { display: flex; }
  header.site-nav { position: sticky; }
}