/* =========================================================
   Yuan Shan — Personal Website
   Editorial × Tech Researcher · v2 (cool / dark-first)
   ========================================================= */

/* ---------- Design tokens ---------- */
:root {
  /* type */
  --font-display: "Instrument Serif", "Cormorant Garamond", "Times New Roman", Georgia, serif;
  --font-serif:   "Cormorant Garamond", "Times New Roman", Georgia, serif;
  --font-sans:    "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono:    "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;

  /* DARK theme (default) */
  --bg:           #0b0c10;
  --bg-alt:       #111319;
  --bg-card:      #15171f;
  --surface:      #181b24;
  --border:       rgba(255,255,255,0.07);
  --border-strong:rgba(255,255,255,0.16);

  --text:         #ececf1;
  --text-muted:   #a8a9b3;
  --text-soft:    #6a6b76;

  --accent:       #ff7849;       /* electric coral / vermillion */
  --accent-hover: #ff8f63;
  --accent-soft:  rgba(255,120,73,.12);

  --gold:         #f4b740;
  --plum:         #b76aa1;

  --shadow-sm: 0 1px 2px rgba(0,0,0,.4), 0 2px 8px rgba(0,0,0,.3);
  --shadow-md: 0 4px 12px rgba(0,0,0,.45), 0 18px 40px rgba(0,0,0,.4);
  --shadow-lg: 0 24px 60px rgba(0,0,0,.55);
  --shadow-glow: 0 0 0 1px rgba(255,120,73,.35), 0 18px 60px -12px rgba(255,120,73,.35);

  --radius-sm: 6px;
  --radius:    14px;
  --radius-lg: 22px;

  --container: 1180px;

  --ease: cubic-bezier(.22,.61,.36,1);
  --ease-out: cubic-bezier(.16,1,.3,1);
}

[data-theme="light"] {
  --bg:           #f7f5f0;
  --bg-alt:       #ede9df;
  --bg-card:      #ffffff;
  --surface:      #ffffff;
  --border:       rgba(20, 22, 30, 0.10);
  --border-strong:rgba(20, 22, 30, 0.20);

  --text:         #14161e;
  --text-muted:   #4f5260;
  --text-soft:    #898b96;

  --accent:       #c2451d;
  --accent-hover: #a23715;
  --accent-soft:  #f4dfd6;

  --gold:         #ad8530;
  --plum:         #88507a;

  --shadow-sm: 0 1px 2px rgba(0,0,0,.04), 0 2px 8px rgba(20,22,30,.05);
  --shadow-md: 0 4px 14px rgba(20,22,30,.07), 0 16px 40px rgba(20,22,30,.07);
  --shadow-lg: 0 20px 60px rgba(20,22,30,.12);
  --shadow-glow: 0 0 0 1px rgba(194,69,29,.35), 0 18px 60px -12px rgba(194,69,29,.30);
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
* { margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.65;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background .35s var(--ease), color .35s var(--ease);
  overflow-x: hidden;
}
img, svg { display: block; max-width: 100%; }
a { color: var(--accent); text-decoration: none; transition: color .2s ease; }
a:hover { color: var(--accent-hover); }
ul, ol { list-style: none; }
button { font: inherit; cursor: pointer; border: 0; background: none; color: inherit; }
em { font-style: italic; }

::selection { background: var(--accent); color: #fff; }

/* ---------- Global grain texture ---------- */
body::before {
  content: "";
  position: fixed;
  inset: -50%;
  pointer-events: none;
  z-index: 100;
  opacity: .035;
  mix-blend-mode: overlay;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='240' height='240'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.95' numOctaves='2' stitchTiles='stitch'/%3E%3CfeColorMatrix values='0 0 0 0 1  0 0 0 0 1  0 0 0 0 1  0 0 0 1 0'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}
[data-theme="light"] body::before { opacity: .055; mix-blend-mode: multiply; }

/* ---------- Layout helpers ---------- */
.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 1.75rem;
}

.section {
  padding: 7rem 0 6rem;
  position: relative;
}
.section-alt { background: var(--bg-alt); }

.section-header {
  display: grid;
  grid-template-columns: auto 1fr;
  align-items: baseline;
  gap: 1rem 1.5rem;
  margin-bottom: 3rem;
  position: relative;
}
.section-num {
  font-family: var(--font-mono);
  font-size: .78rem;
  letter-spacing: .22em;
  color: var(--accent);
  font-weight: 500;
  position: relative;
  padding-left: 1.5rem;
}
.section-num::before {
  content: "";
  position: absolute;
  left: 0; top: 50%;
  width: 1rem; height: 1px;
  background: var(--accent);
}
.section-title {
  font-family: var(--font-display);
  font-weight: 400;
  font-size: clamp(2.4rem, 5vw, 3.75rem);
  letter-spacing: -.015em;
  line-height: 1.0;
  grid-column: 2;
}
.section-sub {
  grid-column: 2;
  color: var(--text-muted);
  margin-top: .25rem;
  font-size: 1.02rem;
}

/* ---------- Navigation ---------- */
.nav-wrap {
  position: sticky;
  top: 0;
  z-index: 50;
  background: color-mix(in srgb, var(--bg) 75%, transparent);
  backdrop-filter: saturate(180%) blur(16px);
  -webkit-backdrop-filter: saturate(180%) blur(16px);
  border-bottom: 1px solid transparent;
  transition: border-color .3s var(--ease), background .3s var(--ease);
}
.nav-wrap.scrolled { border-bottom-color: var(--border); }

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: .75rem;
  color: var(--text);
  font-weight: 600;
  letter-spacing: .005em;
}
.nav-brand:hover { color: var(--text); }
.brand-mark {
  width: 34px; height: 34px;
  display: grid; place-items: center;
  border: 1.5px solid var(--text);
  border-radius: 50%;
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-style: italic;
  font-weight: 400;
  transition: transform .4s var(--ease-out), border-color .3s ease, color .3s ease, background .3s ease;
}
.nav-brand:hover .brand-mark {
  transform: rotate(-15deg) scale(1.06);
  border-color: var(--accent);
  background: var(--accent);
  color: #fff;
}
.brand-name { font-size: .95rem; letter-spacing: .005em; }

.nav-links {
  display: flex;
  gap: 2rem;
}
.nav-links a {
  color: var(--text-muted);
  font-size: .9rem;
  font-weight: 500;
  position: relative;
  padding: .25rem 0;
  letter-spacing: .005em;
}
.nav-links a::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: -2px;
  height: 1.5px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform .35s var(--ease);
}
.nav-links a:hover { color: var(--text); }
.nav-links a:hover::after { transform: scaleX(1); }

.nav-actions { display: flex; align-items: center; gap: .5rem; }

.icon-btn {
  width: 40px; height: 40px;
  display: grid; place-items: center;
  border-radius: 10px;
  color: var(--text);
  transition: background .2s ease, color .2s ease, border-color .2s ease;
  border: 1px solid transparent;
}
.icon-btn:hover {
  background: var(--bg-alt);
  border-color: var(--border);
  color: var(--accent);
}

.icon-sun { display: block; }
.icon-moon { display: none; }
[data-theme="light"] .icon-sun { display: none; }
[data-theme="light"] .icon-moon { display: block; }

.menu-btn { display: none; }

/* ---------- Hero ---------- */
.hero {
  position: relative;
  min-height: calc(100vh - 72px);
  display: flex;
  align-items: center;
  overflow: hidden;
  padding: 5rem 0 6rem;
}
.hero-bg {
  position: absolute; inset: 0;
  background:
    radial-gradient(60% 50% at 12% 25%, color-mix(in srgb, var(--accent) 18%, transparent) 0%, transparent 60%),
    radial-gradient(50% 40% at 88% 78%, color-mix(in srgb, var(--gold) 16%, transparent) 0%, transparent 60%),
    radial-gradient(30% 30% at 70% 18%, color-mix(in srgb, var(--plum) 14%, transparent) 0%, transparent 70%);
  pointer-events: none;
  z-index: 0;
  filter: blur(2px) saturate(115%);
}
.hero-bg::before {
  content: "";
  position: absolute; inset: 0;
  background-image:
    linear-gradient(to right, var(--border) 1px, transparent 1px),
    linear-gradient(to bottom, var(--border) 1px, transparent 1px);
  background-size: 72px 72px;
  mask-image: radial-gradient(ellipse at center, #000 0%, transparent 75%);
  -webkit-mask-image: radial-gradient(ellipse at center, #000 0%, transparent 75%);
  opacity: .45;
}

.hero-grid {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: 1.25fr 1fr;
  align-items: center;
  gap: 4rem;
}

/* eyebrow / status */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: .65rem;
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .2em;
  color: var(--accent);
  text-transform: uppercase;
  margin-bottom: 1.5rem;
  padding: .4rem .85rem;
  border: 1px solid color-mix(in srgb, var(--accent) 35%, transparent);
  border-radius: 999px;
  background: var(--accent-soft);
}
.status-dot {
  width: 7px; height: 7px;
  background: var(--accent);
  border-radius: 50%;
  position: relative;
}
.status-dot::after {
  content: "";
  position: absolute; inset: -4px;
  border-radius: 50%;
  background: var(--accent);
  opacity: .35;
  animation: pulse 1.8s ease-out infinite;
}
@keyframes pulse {
  0%   { transform: scale(.6); opacity: .6; }
  100% { transform: scale(2.2); opacity: 0; }
}

.hero-title {
  font-family: var(--font-display);
  font-weight: 400;
  font-size: clamp(3.4rem, 9vw, 7rem);
  letter-spacing: -0.025em;
  line-height: .95;
  margin-bottom: 2rem;
  color: var(--text);
}
.title-line {
  display: block;
  font-size: .55em;
  font-style: italic;
  color: var(--text-muted);
  margin-bottom: .25rem;
  letter-spacing: 0;
  font-weight: 400;
}
.title-name {
  display: block;
}
.title-name em {
  font-style: italic;
  background: linear-gradient(105deg, var(--accent) 0%, var(--gold) 55%, var(--plum) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  background-size: 200% 100%;
  animation: gradShift 9s ease-in-out infinite;
}
@keyframes gradShift {
  0%, 100% { background-position: 0% 50%; }
  50%      { background-position: 100% 50%; }
}

.hero-tagline {
  font-size: clamp(1.05rem, 1.4vw, 1.18rem);
  color: var(--text-muted);
  max-width: 560px;
  margin-bottom: 2.5rem;
  line-height: 1.7;
}
.hl {
  color: var(--text);
  font-weight: 600;
  position: relative;
  white-space: nowrap;
}
.hl::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: -1px;
  height: 6px;
  background: var(--accent);
  opacity: .22;
  z-index: -1;
  border-radius: 2px;
}
.dot { color: var(--accent); margin: 0 .35em; font-weight: 600; }

.hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: .85rem;
  margin-bottom: 2.75rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: .55rem;
  padding: .85rem 1.5rem;
  border-radius: 999px;
  font-weight: 500;
  font-size: .95rem;
  letter-spacing: .005em;
  border: 1.5px solid transparent;
  transition: all .3s var(--ease-out);
  cursor: pointer;
  position: relative;
  overflow: hidden;
}
.btn::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(120% 100% at 50% 0%, color-mix(in srgb, #fff 18%, transparent) 0%, transparent 60%);
  opacity: 0;
  transition: opacity .3s ease;
}
.btn:hover::before { opacity: 1; }
.btn-sm { padding: .55rem 1rem; font-size: .87rem; }
.btn-primary {
  background: var(--text);
  color: var(--bg);
  border-color: var(--text);
}
.btn-primary:hover {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
  transform: translateY(-2px);
  box-shadow: var(--shadow-glow);
}
.btn-primary svg { transition: transform .3s var(--ease-out); }
.btn-primary:hover svg { transform: translateX(4px); }
.btn-ghost {
  color: var(--text);
  border-color: var(--border-strong);
}
.btn-ghost:hover {
  border-color: var(--text);
  background: var(--bg-alt);
  transform: translateY(-2px);
}

.hero-socials {
  display: flex;
  flex-wrap: wrap;
  gap: 1.25rem 2rem;
  padding-top: 1.75rem;
  border-top: 1px solid var(--border);
  max-width: 600px;
}
.hero-socials a {
  display: inline-flex;
  align-items: center;
  gap: .55rem;
  color: var(--text-muted);
  font-size: .9rem;
  font-weight: 500;
}
.hero-socials a:hover { color: var(--accent); }
.hero-socials svg { transition: transform .25s ease; }
.hero-socials a:hover svg { transform: translateY(-2px); }

/* ---------- Hero portrait ---------- */
.hero-portrait {
  position: relative;
  display: flex;
  justify-content: flex-end;
  align-items: center;
  perspective: 1200px;
}
.portrait-stack {
  position: relative;
  width: 100%;
  max-width: 280px;
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: 1.25rem;
}
.portrait-frame {
  position: relative;
  width: 100%;
  aspect-ratio: 4 / 5;
  transform-style: preserve-3d;
  transition: transform .6s var(--ease-out);
}
.portrait-offset {
  position: absolute;
  inset: 0;
  border-radius: var(--radius-lg);
  background: linear-gradient(135deg, var(--accent) 0%, var(--gold) 60%, var(--plum) 100%);
  transform: translate(18px, 18px) rotate(-2.5deg);
  transition: transform .6s var(--ease-out);
  box-shadow: 0 30px 80px -20px color-mix(in srgb, var(--accent) 50%, transparent);
}
.portrait-image {
  position: relative;
  width: 100%; height: 100%;
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: #f3efe7;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border-strong);
  transform: translateZ(40px);
  z-index: 1;
}
.portrait-image img {
  width: 100%; height: 100%;
  object-fit: cover;
  object-position: 50% 18%;
  transform: scale(1.05);
  transition: transform 1s var(--ease-out), filter .5s ease;
  filter: contrast(1.04) saturate(1.02);
}
.portrait-image::after {
  content: "";
  position: absolute; inset: 0;
  background:
    linear-gradient(160deg, transparent 60%, color-mix(in srgb, var(--accent) 22%, transparent) 100%);
  pointer-events: none;
  mix-blend-mode: multiply;
}
[data-theme="light"] .portrait-image::after { mix-blend-mode: multiply; opacity: .85; }
.portrait-shine {
  position: absolute; inset: 0;
  background: linear-gradient(115deg, transparent 35%, rgba(255,255,255,.15) 48%, transparent 60%);
  transform: translateX(-100%);
  transition: transform 1.4s var(--ease-out);
  pointer-events: none;
}
.portrait-frame:hover .portrait-shine { transform: translateX(100%); }
.portrait-frame:hover .portrait-image img { transform: scale(1.08); }
.portrait-frame:hover { transform: rotateX(2deg) rotateY(-3deg); }
.portrait-frame:hover .portrait-offset { transform: translate(24px, 24px) rotate(-3deg); }

/* registration corners */
.portrait-corners span {
  position: absolute;
  width: 18px; height: 18px;
  border: 1.5px solid var(--accent);
  z-index: 2;
  transition: all .4s var(--ease-out);
}
.portrait-corners span:nth-child(1) { top: -7px;    left: -7px;    border-right: 0; border-bottom: 0; }
.portrait-corners span:nth-child(2) { top: -7px;    right: -7px;   border-left:  0; border-bottom: 0; }
.portrait-corners span:nth-child(3) { bottom: -7px; left: -7px;    border-right: 0; border-top:    0; }
.portrait-corners span:nth-child(4) { bottom: -7px; right: -7px;   border-left:  0; border-top:    0; }
.portrait-frame:hover .portrait-corners span { width: 26px; height: 26px; }

/* small meta card – sibling of portrait, sits clearly below */
.portrait-meta {
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--border-strong);
  border-radius: 10px;
  padding: .75rem .9rem;
  display: grid;
  gap: .25rem;
  font-family: var(--font-mono);
  font-size: .68rem;
  box-shadow: var(--shadow-md);
  transform: rotate(-1.2deg);
  align-self: flex-start;
  margin-left: -8px;
}
.pm-row { display: grid; grid-template-columns: 2.8rem 1fr; gap: .75rem; align-items: baseline; }
.pm-key { color: var(--accent); letter-spacing: .05em; text-transform: uppercase; font-size: .6rem; }
.pm-val { color: var(--text); white-space: nowrap; font-size: .72rem; }

/* scroll hint */
.scroll-hint {
  position: absolute;
  bottom: 1.75rem;
  left: 50%;
  transform: translateX(-50%);
  width: 22px; height: 36px;
  border: 1.5px solid var(--text-soft);
  border-radius: 14px;
  display: grid;
  place-items: start center;
  padding-top: 6px;
  z-index: 1;
}
.scroll-hint span {
  width: 3px; height: 7px;
  background: var(--text-soft);
  border-radius: 2px;
  animation: scrollDot 1.8s infinite var(--ease);
}
@keyframes scrollDot {
  0%   { transform: translateY(0); opacity: 1; }
  60%  { transform: translateY(12px); opacity: 0; }
  100% { transform: translateY(0); opacity: 0; }
}

/* ---------- Marquee ---------- */
.marquee {
  position: relative;
  overflow: hidden;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  padding: 1.1rem 0;
  mask-image: linear-gradient(to right, transparent, #000 8%, #000 92%, transparent);
  -webkit-mask-image: linear-gradient(to right, transparent, #000 8%, #000 92%, transparent);
}
.marquee-track {
  display: inline-flex;
  align-items: center;
  white-space: nowrap;
  animation: marquee 38s linear infinite;
  font-family: var(--font-display);
  font-style: italic;
  font-size: clamp(1.4rem, 3vw, 2.25rem);
  color: var(--text);
}
.marquee-track > span { padding: 0 1.5rem; }
.m-sep {
  color: var(--accent);
  font-style: normal;
  font-size: .8em;
  opacity: .8;
}
@keyframes marquee {
  from { transform: translateX(0); }
  to   { transform: translateX(-50%); }
}

/* ---------- About ---------- */
.about-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  gap: 3rem;
  align-items: start;
}
.about-text .lead {
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 2.5vw, 2.1rem);
  font-weight: 400;
  line-height: 1.35;
  margin-bottom: 1rem;
  color: var(--text);
}
.muted { color: var(--text-muted); }
.muted-inline { color: var(--text-soft); font-weight: 400; font-style: italic; font-size: .85em; }

.about-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.85rem;
  box-shadow: var(--shadow-sm);
  position: relative;
  overflow: hidden;
}
.about-card::before {
  content: "";
  position: absolute;
  top: 0; right: 0;
  width: 80px; height: 80px;
  background: radial-gradient(circle at top right, var(--accent-soft), transparent 70%);
  pointer-events: none;
}
.about-card h3 {
  font-family: var(--font-display);
  font-size: 1.55rem;
  font-weight: 400;
  margin-bottom: 1.25rem;
  padding-bottom: .85rem;
  border-bottom: 1px solid var(--border);
  letter-spacing: .005em;
  position: relative;
}
.facts { display: grid; gap: .85rem; }
.facts > div {
  display: grid;
  grid-template-columns: 5.5rem 1fr;
  gap: 1rem;
  align-items: baseline;
  font-size: .92rem;
}
.facts dt {
  font-family: var(--font-mono);
  font-size: .68rem;
  text-transform: uppercase;
  letter-spacing: .14em;
  color: var(--text-soft);
  font-weight: 500;
}
.facts dd { color: var(--text); }

/* ---------- Research / Paper ---------- */
.subgroup-title {
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .22em;
  text-transform: uppercase;
  color: var(--text-soft);
  margin-bottom: 1.25rem;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: .8rem;
}
.subgroup-title::before {
  content: "";
  width: 1.5rem; height: 1px;
  background: var(--text-soft);
}

.paper-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 2.5rem 2.5rem 2.25rem;
  box-shadow: var(--shadow-md);
  position: relative;
  overflow: hidden;
  transition: transform .4s var(--ease-out), border-color .3s ease, box-shadow .3s ease;
}
.paper-card:hover {
  transform: translateY(-3px);
  border-color: var(--border-strong);
}
.paper-card::before {
  content: "";
  position: absolute; left: 0; top: 0; bottom: 0;
  width: 4px;
  background: linear-gradient(to bottom, var(--accent), var(--gold), var(--plum));
}
.paper-card-placeholder {
  border-style: dashed;
  border-color: var(--border-strong);
  background: transparent;
  box-shadow: none;
}
.paper-card-placeholder::before {
  background: linear-gradient(to bottom, var(--text-soft), transparent);
  opacity: .5;
}

.paper-badge {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
  margin-bottom: 1.25rem;
}
.badge {
  display: inline-block;
  padding: .35rem .8rem;
  border-radius: 999px;
  font-size: .72rem;
  font-weight: 500;
  letter-spacing: .04em;
  background: var(--bg-alt);
  color: var(--text-muted);
  border: 1px solid var(--border);
  font-family: var(--font-mono);
  text-transform: uppercase;
}
.badge-accent {
  background: var(--accent-soft);
  color: var(--accent);
  border-color: color-mix(in srgb, var(--accent) 35%, transparent);
}
.badge-soft {
  background: transparent;
  color: var(--text-soft);
  border-style: dashed;
}
.badge-inline {
  display: inline-block;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: .76rem;
  font-weight: 500;
  padding: .25rem .7rem;
  border-radius: 6px;
  margin-bottom: .65rem;
  font-family: var(--font-mono);
  letter-spacing: .04em;
}

.paper-title {
  font-family: var(--font-display);
  font-size: clamp(1.55rem, 2.4vw, 2rem);
  font-weight: 400;
  line-height: 1.2;
  margin-bottom: .65rem;
  color: var(--text);
  letter-spacing: -.005em;
}
.paper-venue {
  font-size: .94rem;
  color: var(--text-muted);
  margin-bottom: 1.25rem;
  font-style: italic;
}
.paper-abstract {
  color: var(--text-muted);
  margin-bottom: 1.5rem;
  font-size: .98rem;
  line-height: 1.75;
}
.paper-abstract strong { color: var(--text); font-weight: 600; }

.chip-row {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
  margin-bottom: 1.5rem;
}
.chip {
  font-family: var(--font-mono);
  font-size: .7rem;
  padding: .3rem .65rem;
  background: var(--bg-alt);
  color: var(--text-muted);
  border-radius: 4px;
  letter-spacing: .04em;
  border: 1px solid var(--border);
}
.chip-soft {
  background: transparent;
  border: 1px dashed var(--border-strong);
  color: var(--text-soft);
}

.paper-actions {
  display: flex;
  flex-wrap: wrap;
  gap: .65rem;
}

/* ---------- Projects ---------- */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
  margin-bottom: 2.5rem;
}
.filter {
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .06em;
  text-transform: uppercase;
  padding: .5rem 1rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text-muted);
  transition: all .25s var(--ease);
}
.filter:hover {
  border-color: var(--text);
  color: var(--text);
}
.filter.active {
  background: var(--text);
  color: var(--bg);
  border-color: var(--text);
}

.project-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(330px, 1fr));
  gap: 1.5rem;
}

.project-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.65rem;
  display: flex;
  flex-direction: column;
  gap: .9rem;
  transition: transform .35s var(--ease-out), box-shadow .35s var(--ease-out), border-color .35s var(--ease-out);
  position: relative;
  overflow: hidden;
}
.project-card::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(600px circle at var(--mx, 50%) var(--my, 0%), color-mix(in srgb, var(--accent) 8%, transparent), transparent 40%);
  opacity: 0;
  transition: opacity .4s ease;
  pointer-events: none;
}
.project-card::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: 0;
  height: 2px;
  background: linear-gradient(to right, var(--accent), var(--gold), var(--plum));
  opacity: 0;
  transition: opacity .3s ease;
  border-bottom-left-radius: var(--radius);
  border-bottom-right-radius: var(--radius);
}
.project-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-md);
  border-color: var(--border-strong);
}
.project-card:hover::before { opacity: 1; }
.project-card:hover::after { opacity: 1; }
.project-card.hidden { display: none; }

.project-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: .78rem;
  position: relative;
  z-index: 1;
}
.project-date {
  font-family: var(--font-mono);
  color: var(--text-soft);
  letter-spacing: .06em;
}
.project-pill {
  font-family: var(--font-mono);
  padding: .22rem .6rem;
  border-radius: 4px;
  font-size: .68rem;
  letter-spacing: .05em;
  font-weight: 500;
  text-transform: uppercase;
}
.pill-llm    { background: rgba(255,120,73,.12);  color: var(--accent); }
.pill-causal { background: rgba(244,183,64,.14); color: var(--gold); }
.pill-stats  { background: rgba(120,160,220,.13); color: #94b8e6; }
.pill-optim  { background: rgba(110,200,150,.13); color: #8de0b3; }
.pill-viz    { background: rgba(183,106,161,.14); color: var(--plum); }
.pill-sports { background: rgba(70,180,200,.13); color: #6ed4e0; }
[data-theme="light"] .pill-stats  { background: rgba(60,90,150,.10);  color: #4670a8; }
[data-theme="light"] .pill-optim  { background: rgba(60,130,90,.10);  color: #3a8a5e; }
[data-theme="light"] .pill-viz    { background: rgba(140,80,160,.10); color: #8757aa; }
[data-theme="light"] .pill-sports { background: rgba(40,130,160,.10); color: #2d7894; }

.project-title {
  font-family: var(--font-display);
  font-size: 1.45rem;
  font-weight: 400;
  line-height: 1.2;
  color: var(--text);
  position: relative;
  z-index: 1;
}
.project-desc {
  color: var(--text-muted);
  font-size: .94rem;
  line-height: 1.65;
  flex: 1;
  position: relative;
  z-index: 1;
}
.tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: .35rem;
  position: relative;
  z-index: 1;
}
.tag-row li {
  font-family: var(--font-mono);
  font-size: .66rem;
  color: var(--text-soft);
  background: var(--bg-alt);
  padding: .22rem .5rem;
  border-radius: 4px;
  letter-spacing: .03em;
}
.project-actions {
  display: flex;
  gap: 1.25rem;
  padding-top: .25rem;
  font-size: .9rem;
  font-weight: 500;
  position: relative;
  z-index: 1;
}
.project-actions a { display: inline-flex; align-items: center; gap: .25rem; }

.more-link {
  text-align: center;
  margin-top: 3rem;
  font-size: .95rem;
}
.more-link a {
  color: var(--text);
  border-bottom: 1px solid var(--accent);
  padding-bottom: .15rem;
  transition: color .2s ease, border-color .2s ease;
}
.more-link a:hover { color: var(--accent); }

/* ---------- Timeline ---------- */
.timeline {
  position: relative;
  padding-left: 1.5rem;
}
.timeline::before {
  content: "";
  position: absolute;
  left: 7px; top: 8px; bottom: 8px;
  width: 2px;
  background: linear-gradient(to bottom, var(--accent), var(--gold), transparent);
  opacity: .55;
}

.timeline-item {
  position: relative;
  display: grid;
  grid-template-columns: 12rem 1fr;
  gap: 2rem;
  padding-bottom: 2.5rem;
  align-items: start;
}
.timeline-item:last-child { padding-bottom: 0; }

.t-dot {
  position: absolute;
  left: -1.5rem;
  top: 12px;
  width: 16px; height: 16px;
  background: var(--bg-alt);
  border: 2px solid var(--accent);
  border-radius: 50%;
  z-index: 1;
  box-shadow: 0 0 0 4px color-mix(in srgb, var(--accent) 18%, transparent);
}

.t-time {
  font-family: var(--font-mono);
  font-size: .78rem;
  letter-spacing: .06em;
  color: var(--text-soft);
  padding-top: .5rem;
  text-transform: uppercase;
}

.t-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.65rem 1.85rem;
  box-shadow: var(--shadow-sm);
  transition: border-color .25s ease, transform .25s ease;
  position: relative;
  overflow: hidden;
}
.t-card::before {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 1px;
  background: linear-gradient(to right, transparent, var(--accent), transparent);
  opacity: 0;
  transition: opacity .3s ease;
}
.t-card:hover {
  border-color: var(--border-strong);
  transform: translateX(6px);
}
.t-card:hover::before { opacity: 1; }
.t-card h3 {
  font-family: var(--font-display);
  font-size: 1.4rem;
  font-weight: 400;
  margin-bottom: .25rem;
  color: var(--text);
  letter-spacing: -.005em;
}
.t-org {
  font-size: .92rem;
  color: var(--accent);
  margin-bottom: .85rem;
  font-weight: 500;
}
.t-card ul { display: grid; gap: .55rem; }
.t-card ul li {
  position: relative;
  padding-left: 1.1rem;
  color: var(--text-muted);
  font-size: .94rem;
  line-height: 1.65;
}
.t-card ul li::before {
  content: "";
  position: absolute;
  left: 0; top: .65em;
  width: 5px; height: 5px;
  background: var(--accent);
  border-radius: 50%;
  opacity: .7;
}
.t-card strong { color: var(--text); font-weight: 600; }

/* ---------- Education ---------- */
.edu-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
  margin-bottom: 3.5rem;
}
.edu-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.85rem;
  box-shadow: var(--shadow-sm);
  transition: transform .3s var(--ease-out), box-shadow .3s var(--ease-out), border-color .3s ease;
  position: relative;
  overflow: hidden;
}
.edu-card::after {
  content: "";
  position: absolute;
  bottom: -50%; right: -25%;
  width: 200px; height: 200px;
  background: radial-gradient(circle, var(--accent-soft), transparent 70%);
  opacity: 0;
  transition: opacity .35s ease;
  pointer-events: none;
}
.edu-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--border-strong);
}
.edu-card:hover::after { opacity: 1; }
.edu-head {
  margin-bottom: 1rem;
  padding-bottom: .85rem;
  border-bottom: 1px solid var(--border);
}
.edu-head h3 {
  font-family: var(--font-display);
  font-size: 1.55rem;
  font-weight: 400;
  color: var(--text);
  letter-spacing: -.005em;
}
.edu-degree {
  color: var(--text);
  margin-bottom: .35rem;
  font-size: .98rem;
}
.edu-meta {
  color: var(--text-muted);
  font-size: .92rem;
  margin-top: .35rem;
}
.edu-time {
  margin-top: .85rem;
  color: var(--text-soft);
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .04em;
  text-transform: uppercase;
}

.honors {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.85rem 2rem;
  box-shadow: var(--shadow-sm);
}
.honors-title {
  font-family: var(--font-display);
  font-size: 1.45rem;
  font-weight: 400;
  margin-bottom: 1rem;
  padding-bottom: .85rem;
  border-bottom: 1px solid var(--border);
}
.honors-list {
  display: grid;
  gap: .65rem;
}
.honors-list li {
  display: grid;
  grid-template-columns: 1.5rem 1fr;
  gap: .5rem;
  font-size: .95rem;
  color: var(--text);
}
.h-mark {
  color: var(--accent);
  font-weight: 600;
}

/* ---------- Contact ---------- */
.contact-block { text-align: center; }
.contact-block .section-header {
  justify-content: center;
  text-align: left;
  display: inline-grid;
  margin: 0 auto 2rem;
}
.contact-lead {
  font-family: var(--font-display);
  font-size: clamp(1.4rem, 2.5vw, 1.85rem);
  line-height: 1.45;
  font-weight: 400;
  max-width: 680px;
  margin: 0 auto 2rem;
  color: var(--text);
}
.contact-actions {
  display: flex;
  justify-content: center;
  gap: .75rem;
  margin-bottom: 3rem;
}
.contact-meta {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 1.5rem 2rem;
  max-width: 720px;
  margin: 0 auto;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
  text-align: left;
}
.contact-meta li {
  display: flex;
  flex-direction: column;
  gap: .35rem;
}
.contact-meta strong {
  font-family: var(--font-mono);
  font-size: .68rem;
  text-transform: uppercase;
  letter-spacing: .14em;
  color: var(--text-soft);
  font-weight: 500;
}
.contact-meta a, .contact-meta span {
  color: var(--text);
  font-size: .95rem;
}
.contact-meta a:hover { color: var(--accent); }

/* ---------- Footer ---------- */
.footer {
  border-top: 1px solid var(--border);
  padding: 2.25rem 0;
  background: var(--bg);
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
  font-size: .85rem;
  color: var(--text-soft);
}
.footer-meta { font-family: var(--font-mono); font-size: .78rem; letter-spacing: .04em; }

/* ---------- Reveal animation ---------- */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity .9s var(--ease-out), transform .9s var(--ease-out);
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  html { scroll-behavior: auto; }
  .scroll-hint span,
  .marquee-track,
  .title-name em,
  .status-dot::after { animation: none; }
}

/* ---------- Responsive ---------- */
@media (max-width: 980px) {
  .hero-grid { grid-template-columns: 1fr; gap: 3rem; }
  .hero-portrait { order: -1; justify-content: center; }
  .portrait-stack { max-width: 240px; align-items: center; }
  .portrait-meta { font-size: .64rem; margin-left: 0; }
}

@media (max-width: 880px) {
  .nav-links {
    position: absolute;
    top: 72px; left: 0; right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    gap: 0;
    padding: .75rem 1.5rem 1.5rem;
    transform: translateY(-12px);
    opacity: 0;
    pointer-events: none;
    transition: opacity .25s ease, transform .25s ease;
  }
  .nav-links.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }
  .nav-links li { border-top: 1px solid var(--border); }
  .nav-links a { display: block; padding: .9rem 0; font-size: 1rem; }
  .menu-btn { display: grid; }

  .about-grid { grid-template-columns: 1fr; gap: 2rem; }

  .timeline { padding-left: 1.25rem; }
  .timeline-item { grid-template-columns: 1fr; gap: .5rem; }
  .t-time { padding-top: 0; }

  .section { padding: 5rem 0 4rem; }

  .hero { min-height: auto; padding: 3rem 0 5rem; }
  .scroll-hint { display: none; }

  .paper-card { padding: 1.85rem 1.5rem; }
}

@media (max-width: 520px) {
  body { font-size: 16px; }
  .container { padding: 0 1.25rem; }
  .hero-title { font-size: 3.4rem; }
  .section-header { grid-template-columns: 1fr; }
  .section-num { grid-column: 1; }
  .section-title, .section-sub { grid-column: 1; }
  .contact-meta { text-align: center; }
  .contact-meta li { align-items: center; }
  .portrait-stack { max-width: 220px; }
  .portrait-meta { transform: rotate(-1.2deg); }
}