:root {
  /* ---- light: minimal, airy, techy (default) ---- */
  --bg: #ffffff;
  --bg-soft: #f7f8fc;
  --panel: #ffffff;
  --panel-border: rgba(15, 23, 42, 0.09);
  --shadow: 0 8px 30px rgba(15, 23, 42, 0.06);
  --shadow-hover: 0 18px 50px rgba(79, 70, 229, 0.14);
  --text: #0f172a;
  --muted: #64748b;
  --c1: #4f46e5;   /* indigo */
  --c2: #0ea5e9;   /* sky    */
  --c3: #db2777;   /* pink   */
  --grad: linear-gradient(120deg, var(--c1), var(--c2));
  --grad-3: linear-gradient(120deg, var(--c1), var(--c2), var(--c3));
  --aurora-op: 0.5;
  --grid-op: 0.55;
  --star: 79, 70, 229;   /* rgb of particles */
  --star-max: 0.4;
  --maxw: 1080px;
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

:root[data-theme="dark"] {
  --bg: #05060a;
  --bg-soft: #0b0d16;
  --panel: rgba(255, 255, 255, 0.03);
  --panel-border: rgba(255, 255, 255, 0.08);
  --shadow: 0 8px 30px rgba(0, 0, 0, 0.4);
  --shadow-hover: 0 18px 50px rgba(33, 212, 253, 0.25);
  --text: #e8eaf2;
  --muted: #8a90a6;
  --c1: #7c5cff;
  --c2: #21d4fd;
  --c3: #ff5f9e;
  --aurora-op: 1;
  --grid-op: 0.5;
  --star: 180, 200, 255;
  --star-max: 0.6;
}

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

body {
  margin: 0;
  font-family: "Inter", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  transition: background 0.5s var(--ease), color 0.5s var(--ease);
}

/* ---------- animated background ---------- */
#starfield {
  position: fixed;
  inset: 0;
  z-index: -3;
  width: 100%;
  height: 100%;
}
/* soft radial fade so the constellation is densest up top, airy toward footer */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background: radial-gradient(120% 80% at 50% 0%, color-mix(in srgb, var(--c1) 6%, transparent), transparent 60%);
}

/* ---------- scroll progress ---------- */
#scroll-progress {
  position: fixed;
  top: 0; left: 0;
  height: 3px;
  width: 0;
  background: var(--grad-3);
  z-index: 100;
  box-shadow: 0 0 14px color-mix(in srgb, var(--c1) 60%, transparent);
}

/* ---------- nav ---------- */
#nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px clamp(20px, 5vw, 60px);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  background: color-mix(in srgb, var(--bg) 72%, transparent);
  border-bottom: 1px solid transparent;
  transition: border-color 0.4s var(--ease), padding 0.4s var(--ease), box-shadow 0.4s;
}
#nav.scrolled { border-bottom-color: var(--panel-border); padding-top: 12px; padding-bottom: 12px; box-shadow: 0 4px 24px rgba(15, 23, 42, 0.04); }
.brand {
  font-family: "Space Grotesk", sans-serif;
  font-weight: 700;
  font-size: 1.35rem;
  letter-spacing: 1px;
  text-decoration: none;
  color: var(--text);
}
.brand span { color: var(--c2); }
.nav-links { display: flex; gap: clamp(14px, 2.5vw, 34px); }
.nav-links a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
  position: relative;
  transition: color 0.3s;
}
.nav-links a::after {
  content: "";
  position: absolute;
  left: 0; bottom: -5px;
  width: 0; height: 2px;
  background: var(--grad);
  transition: width 0.3s var(--ease);
}
.nav-links a:hover { color: var(--text); }
.nav-links a:hover::after { width: 100%; }
#theme-toggle {
  background: var(--panel);
  border: 1px solid var(--panel-border);
  color: var(--text);
  width: 36px; height: 36px;
  border-radius: 50%;
  cursor: pointer;
  font-size: 1rem;
  box-shadow: var(--shadow);
  transition: transform 0.4s var(--ease), background 0.3s;
}
#theme-toggle:hover { transform: rotate(180deg); }

/* ---------- layout ---------- */
main { position: relative; z-index: 1; }
.section {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(70px, 12vh, 140px) clamp(20px, 5vw, 40px);
}
.section-head {
  display: flex;
  align-items: baseline;
  gap: 16px;
  margin-bottom: 48px;
}
.section-idx {
  font-family: "JetBrains Mono", monospace;
  color: var(--c2);
  font-size: 0.95rem;
  opacity: 0.85;
}
.section-head h2 {
  font-family: "Space Grotesk", sans-serif;
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  margin: 0;
  font-weight: 600;
  letter-spacing: -0.5px;
}

/* ---------- hero ---------- */
.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 clamp(20px, 5vw, 40px);
  position: relative;
}
.avatar {
  width: 116px;
  height: 116px;
  border-radius: 50%;
  padding: 4px;
  margin: 0 0 26px;
  background: var(--grad-3);
  background-size: 200% auto;
  box-shadow: 0 12px 40px color-mix(in srgb, var(--c1) 34%, transparent);
  animation: shine 6s linear infinite, float 5s ease-in-out infinite;
  transition: transform 0.4s var(--ease);
}
.avatar:hover { transform: scale(1.06) rotate(-2deg); }
.avatar img {
  width: 100%;
  height: 100%;
  border-radius: 50%;
  object-fit: cover;
  border: 3px solid var(--bg);
  display: block;
}
@keyframes float { 0%, 100% { transform: translateY(0); } 50% { transform: translateY(-8px); } }
.eyebrow {
  font-family: "JetBrains Mono", monospace;
  color: var(--c2);
  letter-spacing: 3px;
  text-transform: uppercase;
  font-size: 0.8rem;
  margin: 0 0 10px;
}
.hero h1 {
  font-family: "Space Grotesk", sans-serif;
  font-size: clamp(2.6rem, 9.5vw, 7rem);
  line-height: 0.98;
  margin: 0;
  font-weight: 700;
  letter-spacing: -2px;
}
.hero h1 .line { display: inline; }
.gradient-text {
  background: var(--grad-3);
  background-size: 200% auto;
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  animation: shine 6s linear infinite;
}
@keyframes shine { to { background-position: 200% center; } }
.cursor { animation: blink 1.1s steps(1) infinite; color: var(--c2); -webkit-text-fill-color: var(--c2); }
@keyframes blink { 50% { opacity: 0; } }
.tagline {
  position: relative;
  font-size: clamp(1.1rem, 2.3vw, 1.55rem);
  color: var(--muted);
  max-width: 620px;
  margin: 28px 0 26px;
  padding-left: 22px;
  line-height: 1.55;
}
.tagline::before {
  content: "";
  position: absolute;
  left: 0;
  top: 5px;
  bottom: 5px;
  width: 3px;
  border-radius: 3px;
  background: linear-gradient(var(--c1), var(--c2), var(--c3));
  box-shadow: 0 0 14px color-mix(in srgb, var(--c2) 45%, transparent);
}
.tagline em {
  font-style: normal;
  font-weight: 700;
  position: relative;
  color: var(--text);
  padding: 0 1px;
}
.tagline em.kw-see { color: var(--c1); }
.tagline em.kw-reason { color: var(--c2); }
.tagline em.kw-act { color: var(--c3); }
.tagline em[class^="kw-"]::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -3px;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  opacity: 0.4;
}
.type-caret {
  display: inline-block;
  width: 2px;
  height: 1.05em;
  background: var(--c2);
  margin-left: 3px;
  vertical-align: -3px;
  animation: blink 1.1s steps(1) infinite;
}
.type-caret.done { animation: none; opacity: 0; transition: opacity 0.5s; }
.hero-meta { display: flex; gap: 12px; flex-wrap: wrap; margin-bottom: 34px; }
.chip {
  font-size: 0.82rem;
  padding: 7px 14px;
  border: 1px solid var(--panel-border);
  border-radius: 100px;
  background: var(--panel);
  color: var(--text);
  box-shadow: var(--shadow);
}
.hero-cta { display: flex; gap: 14px; flex-wrap: wrap; }
.btn {
  padding: 13px 26px;
  border-radius: 100px;
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
  transition: transform 0.3s var(--ease), box-shadow 0.3s;
  display: inline-block;
}
.btn.primary { background: var(--grad); color: #fff; box-shadow: 0 8px 30px color-mix(in srgb, var(--c1) 40%, transparent); }
.btn.primary:hover { transform: translateY(-3px); box-shadow: 0 14px 40px color-mix(in srgb, var(--c2) 45%, transparent); }
.btn.ghost { border: 1px solid var(--panel-border); color: var(--text); background: var(--panel); box-shadow: var(--shadow); }
.btn.ghost:hover { transform: translateY(-3px); border-color: var(--c2); }

.scroll-hint {
  position: absolute;
  bottom: 30px; left: 50%;
  transform: translateX(-50%);
  color: var(--muted);
  font-family: "JetBrains Mono", monospace;
  font-size: 0.72rem;
  letter-spacing: 2px;
  text-transform: uppercase;
  display: flex; flex-direction: column; align-items: center; gap: 8px;
}
.scroll-hint span {
  width: 1px; height: 42px;
  background: linear-gradient(var(--c2), transparent);
  animation: scrolldown 2s ease-in-out infinite;
  transform-origin: top;
}
@keyframes scrolldown { 0%,100% { transform: scaleY(0.3); opacity: 0.4; } 50% { transform: scaleY(1); opacity: 1; } }

/* ---------- stats ---------- */
.stats {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 clamp(20px, 5vw, 40px);
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}
.stat {
  border: 1px solid var(--panel-border);
  background: var(--panel);
  border-radius: 18px;
  padding: 26px 16px;
  text-align: center;
  box-shadow: var(--shadow);
  transition: transform 0.4s var(--ease), box-shadow 0.4s, border-color 0.4s;
}
.stat:hover { transform: translateY(-6px); border-color: color-mix(in srgb, var(--c2) 50%, transparent); box-shadow: var(--shadow-hover); }
.stat .num {
  display: block;
  font-family: "Space Grotesk", sans-serif;
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 700;
  background: var(--grad);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.stat .label { color: var(--muted); font-size: 0.85rem; }
.stats-source {
  grid-column: 1 / -1;
  margin: 0;
  color: var(--muted);
  font-size: 0.78rem;
  line-height: 1.6;
  text-align: center;
}
.stats-source a { color: var(--c1); text-decoration: none; }
.stats-source a:hover { text-decoration: underline; }

/* ---------- about ---------- */
.about-grid { display: grid; grid-template-columns: 1.6fr 1fr; gap: 48px; }
.about-text p { font-size: 1.05rem; margin: 0 0 18px; color: var(--muted); }
.about-text strong { color: var(--text); }
.about-text a, .timeline a { color: var(--c1); text-decoration: none; border-bottom: 1px solid transparent; transition: border-color 0.3s; font-weight: 600; }
.about-text a:hover, .timeline a:hover { border-bottom-color: var(--c1); }
.timeline a strong { color: var(--c1); }
.open-note { display: flex; align-items: center; gap: 10px; }
.pulse-dot {
  width: 10px; height: 10px; border-radius: 50%;
  background: #16a34a;
  box-shadow: 0 0 0 0 rgba(22, 163, 74, 0.5);
  animation: pulse 2s infinite;
  flex-shrink: 0;
}
@keyframes pulse {
  0% { box-shadow: 0 0 0 0 rgba(22, 163, 74, 0.5); }
  70% { box-shadow: 0 0 0 12px rgba(22, 163, 74, 0); }
  100% { box-shadow: 0 0 0 0 rgba(22, 163, 74, 0); }
}
.about-side h3 {
  font-family: "Space Grotesk", sans-serif;
  font-size: 0.95rem;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--muted);
  margin: 0 0 14px;
}
.about-side h3:not(:first-child) { margin-top: 28px; }
.tags { list-style: none; padding: 0; margin: 0; display: flex; flex-wrap: wrap; gap: 9px; }
.tags li {
  font-size: 0.82rem;
  padding: 6px 13px;
  border-radius: 8px;
  background: var(--bg-soft);
  border: 1px solid var(--panel-border);
  transition: transform 0.25s, border-color 0.25s, color 0.25s;
}
.tags li:hover { transform: translateY(-3px); border-color: var(--c1); color: var(--c1); }
.tags.alt li:hover { border-color: var(--c3); color: var(--c3); }

/* ---------- research cards ---------- */
.cards { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; }
.card {
  position: relative;
  border: 1px solid var(--panel-border);
  background: var(--panel);
  border-radius: 20px;
  padding: 30px;
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: transform 0.4s var(--ease), border-color 0.4s, box-shadow 0.4s;
}
.card:hover { transform: translateY(-8px); border-color: color-mix(in srgb, var(--c2) 55%, transparent); box-shadow: var(--shadow-hover); }
.card-glow {
  position: absolute;
  width: 300px; height: 300px;
  background: radial-gradient(circle, color-mix(in srgb, var(--c1) 22%, transparent), transparent 65%);
  top: var(--my, 50%); left: var(--mx, 50%);
  transform: translate(-50%, -50%);
  opacity: 0;
  transition: opacity 0.4s;
  pointer-events: none;
}
.card:hover .card-glow { opacity: 1; }
.card-emoji { font-size: 1.8rem; display: block; margin-bottom: 14px; position: relative; }
.card h3 { font-family: "Space Grotesk", sans-serif; margin: 0 0 10px; font-size: 1.2rem; position: relative; }
.card p { margin: 0; color: var(--muted); font-size: 0.95rem; position: relative; }

/* ---------- publications ---------- */
.pub-list { list-style: none; padding: 0; margin: 0; }
.pub {
  display: grid;
  grid-template-columns: 90px 1fr;
  gap: 22px;
  padding: 26px 0;
  border-top: 1px solid var(--panel-border);
  transition: padding-left 0.35s var(--ease);
}
.pub:hover { padding-left: 12px; }
.pub-year { font-family: "JetBrains Mono", monospace; color: var(--muted); font-size: 0.95rem; padding-top: 4px; }
.pub-fig {
  display: block;
  margin: 0 0 16px;
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  overflow: hidden;
  background: #fff;
  padding: 10px;
  box-shadow: var(--shadow);
  transition: transform 0.35s var(--ease), box-shadow 0.35s, border-color 0.35s;
}
.pub-fig img { display: block; width: 100%; height: auto; border-radius: 4px; }
.pub-fig:hover { transform: translateY(-4px); box-shadow: var(--shadow-hover); border-color: color-mix(in srgb, var(--c2) 45%, transparent); }
.pub-body h3 { font-family: "Space Grotesk", sans-serif; font-size: 1.15rem; margin: 8px 0 8px; line-height: 1.35; }
.pub-body h3 a { color: inherit; text-decoration: none; transition: color 0.3s; }
.pub-body h3 a:hover { color: var(--c1); }
.arxiv-link {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.72rem;
  font-weight: 500;
  color: var(--c1);
  text-decoration: none;
  padding: 3px 10px;
  border: 1px solid color-mix(in srgb, var(--c1) 35%, transparent);
  border-radius: 100px;
  transition: background 0.3s, color 0.3s;
}
.arxiv-link:hover { background: var(--c1); color: #fff; }
.authors { color: var(--muted); font-size: 0.9rem; margin: 0 0 12px; }
.authors strong { color: var(--c1); }
.venue {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 600;
  padding: 4px 11px;
  border-radius: 6px;
  letter-spacing: 0.5px;
}
.venue.neurips { background: color-mix(in srgb, var(--c1) 14%, transparent); color: var(--c1); }
.venue.spotlight { background: color-mix(in srgb, var(--c3) 14%, transparent); color: var(--c3); }
.venue.acl { background: color-mix(in srgb, var(--c2) 14%, transparent); color: #0284c7; }
.venue.arxiv { background: var(--bg-soft); color: var(--muted); border: 1px solid var(--panel-border); }
.pub-tags { display: flex; gap: 8px; flex-wrap: wrap; }
.pub-tags span {
  font-size: 0.72rem;
  color: var(--muted);
  border: 1px solid var(--panel-border);
  padding: 3px 9px;
  border-radius: 100px;
}
.pub-tags span:first-child { color: var(--c1); border-color: color-mix(in srgb, var(--c1) 40%, transparent); }
.scholar-link {
  display: inline-block;
  margin-top: 32px;
  color: var(--c1);
  text-decoration: none;
  font-weight: 600;
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s;
}
.scholar-link:hover { border-bottom-color: var(--c1); }

/* ---------- timeline ---------- */
.timeline { list-style: none; padding: 0; margin: 0; position: relative; }
.timeline::before {
  content: "";
  position: absolute;
  left: 7px; top: 6px; bottom: 6px;
  width: 2px;
  background: linear-gradient(var(--c1), var(--c2), transparent);
}
.timeline li { position: relative; padding: 0 0 26px 36px; }
.timeline li::before {
  content: "";
  position: absolute;
  left: 0; top: 6px;
  width: 16px; height: 16px;
  border-radius: 50%;
  background: var(--bg);
  border: 3px solid var(--c2);
  box-shadow: 0 0 12px color-mix(in srgb, var(--c2) 50%, transparent);
}
.timeline .date { font-family: "JetBrains Mono", monospace; color: var(--c2); font-size: 0.85rem; }
.timeline p { margin: 4px 0 0; color: var(--muted); }
.timeline p strong { color: var(--text); }

/* ---------- contact ---------- */
.contact { text-align: center; }
.contact .section-head { justify-content: center; }
.contact-lead { color: var(--muted); font-size: 1.1rem; margin: 0 0 34px; }
.contact-links { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }
.contact-btn {
  display: flex; align-items: center; gap: 10px;
  padding: 14px 26px;
  border-radius: 14px;
  border: 1px solid var(--panel-border);
  background: var(--panel);
  color: var(--text);
  text-decoration: none;
  font-weight: 600;
  box-shadow: var(--shadow);
  transition: transform 0.35s var(--ease), border-color 0.35s, box-shadow 0.35s;
}
.contact-btn:hover { transform: translateY(-5px); border-color: var(--c2); box-shadow: var(--shadow-hover); }
.contact-btn .ic { font-size: 1.1rem; }

/* ---------- footer ---------- */
footer {
  text-align: center;
  padding: 40px 20px;
  color: var(--muted);
  font-size: 0.85rem;
  border-top: 1px solid var(--panel-border);
}

/* ---------- desktop pet (cursor-chasing cat) ---------- */
#pet {
  position: fixed;
  top: 0;
  left: 0;
  width: 52px;
  height: 54px;
  margin-left: -26px;
  margin-top: -30px;
  z-index: 70;
  pointer-events: none;
  will-change: transform;
  filter: drop-shadow(0 6px 8px rgba(15, 23, 42, 0.22));
}
.pet-flip { transform: scaleX(var(--f, -1)); transition: transform 0.15s ease; }
.pet-bob { transform-origin: 50% 90%; }
.catsvg { display: block; }
.pet-tail {
  transform-box: fill-box;
  transform-origin: 0% 100%;
  animation: tailwag 1.1s ease-in-out infinite;
}
@keyframes tailwag { 0%, 100% { transform: rotate(-10deg); } 50% { transform: rotate(16deg); } }
/* running: quick body bob + faster tail */
#pet.run .pet-bob { animation: petbob 0.32s ease-in-out infinite; }
#pet.run .pet-tail { animation-duration: 0.5s; }
@keyframes petbob { 0%, 100% { transform: translateY(0) scaleY(1); } 50% { transform: translateY(-3px) scaleY(1.05); } }
/* idle: gentle breathing */
#pet:not(.run):not(.sleep) .pet-bob { animation: petbreathe 2.6s ease-in-out infinite; }
@keyframes petbreathe { 0%, 100% { transform: scale(1); } 50% { transform: scale(1.03); } }
/* sleeping: slouch + zzz */
#pet.sleep .pet-bob { animation: petsleep 3.4s ease-in-out infinite; transform-origin: 50% 100%; }
@keyframes petsleep { 0%, 100% { transform: scaleY(0.96) translateY(1px); } 50% { transform: scaleY(0.9) translateY(3px); } }
#pet.sleep .pet-tail { animation-duration: 2.4s; }
.zzz {
  position: absolute;
  top: -10px;
  right: -8px;
  font-family: "Space Grotesk", sans-serif;
  font-weight: 700;
  font-size: 0.8rem;
  color: var(--c1);
  opacity: 0;
}
#pet.sleep .zzz { animation: zzz 2.4s ease-out infinite; }
@keyframes zzz {
  0% { opacity: 0; transform: translate(0, 0) scale(0.6); }
  30% { opacity: 0.9; }
  100% { opacity: 0; transform: translate(10px, -22px) scale(1.3); }
}
@media (prefers-reduced-motion: reduce) { #pet { display: none; } }
@media (max-width: 780px) { #pet { display: none; } }

/* ---------- reveal animation ---------- */
.reveal { opacity: 0; transform: translateY(28px); transition: opacity 0.8s var(--ease), transform 0.8s var(--ease); }
.reveal.visible { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
  .reveal { opacity: 1; transform: none; }
}

/* ---------- responsive ---------- */
@media (max-width: 780px) {
  .nav-links { display: none; }
  .about-grid { grid-template-columns: 1fr; gap: 32px; }
  .cards { grid-template-columns: 1fr; }
  .stats { grid-template-columns: repeat(2, 1fr); }
  .pub { grid-template-columns: 1fr; gap: 8px; }
  .pub-year { padding-top: 0; }
}