/* ============================================================
   Yangfu Ren Academic Homepage v2.1
   Design language: Academic Editorial × Spatial Computing
   ============================================================ */

:root {
  --paper: #f7f8fa;
  --paper-2: #ffffff;
  --paper-3: #f0f3f8;
  --ink: #111827;
  --ink-soft: #2f3b4b;
  --muted: #697586;
  --muted-2: #96a0ae;
  --line: rgba(18, 38, 68, .115);
  --line-strong: rgba(18, 38, 68, .22);
  --blue: #173d8d;
  --blue-2: #315fcd;
  --blue-soft: rgba(49, 95, 205, .09);
  --blue-faint: rgba(49, 95, 205, .035);
  --gold: #b79048;
  --gold-soft: rgba(183, 144, 72, .10);
  --surface: rgba(255, 255, 255, .72);
  --surface-strong: rgba(255, 255, 255, .92);
  --shadow-soft: 0 20px 70px rgba(20, 38, 68, .075);
  --shadow-float: 0 28px 70px rgba(20, 38, 68, .13);
  --header-h: 76px;
  --max: 1240px;
  --ease: cubic-bezier(.22, 1, .36, 1);
  --ease-soft: cubic-bezier(.2, .8, .2, 1);
  --serif: ui-serif, "Songti SC", "STSong", "Noto Serif CJK SC", "Source Han Serif SC", Georgia, "Times New Roman", serif;
  --sans: ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
}

html[data-theme="dark"] {
  --paper: #090d14;
  --paper-2: #0d121b;
  --paper-3: #111824;
  --ink: #edf2f8;
  --ink-soft: #cbd5e1;
  --muted: #9aa8ba;
  --muted-2: #718096;
  --line: rgba(226, 235, 247, .11);
  --line-strong: rgba(226, 235, 247, .22);
  --blue: #9eb9ff;
  --blue-2: #789cff;
  --blue-soft: rgba(120, 156, 255, .10);
  --blue-faint: rgba(120, 156, 255, .045);
  --gold: #d8b56c;
  --gold-soft: rgba(216, 181, 108, .10);
  --surface: rgba(17, 24, 36, .70);
  --surface-strong: rgba(15, 22, 33, .94);
  --shadow-soft: 0 22px 74px rgba(0, 0, 0, .28);
  --shadow-float: 0 30px 82px rgba(0, 0, 0, .40);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-width: 320px;
  overflow-x: hidden;
  color: var(--ink);
  background:
    radial-gradient(900px 520px at 74% -10%, var(--blue-soft), transparent 70%),
    radial-gradient(720px 420px at 8% 8%, var(--gold-soft), transparent 76%),
    var(--paper);
  font: 15.5px/1.78 var(--sans);
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }
button, input, textarea, select { font: inherit; }
button { color: inherit; }
img { max-width: 100%; display: block; }
::selection { background: rgba(49,95,205,.16); }

.sr-only,
.skip-link {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}
.skip-link:focus {
  position: fixed !important;
  width: auto !important;
  height: auto !important;
  left: 18px !important;
  top: 18px !important;
  clip: auto !important;
  z-index: 9999;
  padding: 10px 14px !important;
  margin: 0 !important;
  border-radius: 10px;
  color: white;
  background: #173d8d;
}

/* ---------- Global motion / scroll ---------- */
.scroll-progress {
  position: fixed;
  inset: 0 0 auto 0;
  height: 2px;
  z-index: 400;
  pointer-events: none;
}
.scroll-progress span {
  display: block;
  width: 100%;
  height: 100%;
  transform-origin: left center;
  transform: scaleX(0);
  background: linear-gradient(90deg, var(--blue-2), var(--gold));
  box-shadow: 0 0 18px rgba(49,95,205,.22);
}

/* ---------- Header ---------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 300;
  transition: transform .45s var(--ease), background .3s ease, border-color .3s ease, box-shadow .3s ease;
}
.site-header.is-scrolled {
  background: color-mix(in srgb, var(--paper-2) 82%, transparent);
  border-bottom: 1px solid var(--line);
  box-shadow: 0 10px 36px rgba(18,38,68,.055);
  backdrop-filter: blur(20px) saturate(145%);
  -webkit-backdrop-filter: blur(20px) saturate(145%);
}
.site-header.is-hidden { transform: translateY(-110%); }
.header-inner {
  width: min(var(--max), calc(100% - 48px));
  min-height: var(--header-h);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 225px minmax(0, 1fr) 44px;
  align-items: center;
  gap: 22px;
}
.institution-mark {
  display: inline-flex;
  align-items: center;
  min-width: 0;
}
.institution-logo-frame {
  display: block;
  width: 214px;
  height: 52px;
  overflow: hidden;
}
.institution-logo-frame img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  object-position: left center;
  transition: transform .45s var(--ease), filter .25s ease;
}
.institution-mark:hover img { transform: translateX(2px) scale(1.012); }
html[data-theme="dark"] .institution-logo-frame img { filter: brightness(1.4) saturate(.92); }

.primary-nav { min-width: 0; }
.nav-links {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: clamp(8px, 1.2vw, 18px);
}
.nav-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  min-height: 38px;
  padding: 0 2px;
  color: var(--muted);
  font-size: 12.5px;
  font-weight: 620;
  white-space: nowrap;
  transition: color .22s ease, transform .22s var(--ease);
}
.nav-link::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 3px;
  width: 20px;
  height: 2px;
  border-radius: 999px;
  background: var(--blue-2);
  transform: translateX(-50%) scaleX(0);
  transform-origin: center;
  transition: transform .28s var(--ease);
}
.nav-link:hover { color: var(--ink); transform: translateY(-1px); }
.nav-link[aria-current="page"] { color: var(--blue); }
.nav-link[aria-current="page"]::after { transform: translateX(-50%) scaleX(1); }
.nav-toggle { display: none; }
.header-tools { display: flex; justify-content: flex-end; }
.icon-button,
.to-top {
  border: 1px solid var(--line);
  background: color-mix(in srgb, var(--surface-strong) 88%, transparent);
  box-shadow: 0 8px 30px rgba(18,38,68,.055);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  cursor: pointer;
  transition: transform .22s var(--ease), border-color .22s ease, background .22s ease, box-shadow .22s ease;
}
.icon-button {
  width: 38px;
  height: 38px;
  display: grid;
  place-items: center;
  border-radius: 50%;
}
.icon-button svg { width: 18px; height: 18px; fill: none; stroke: currentColor; stroke-width: 1.6; }
.icon-button:hover { transform: translateY(-2px) rotate(-4deg); border-color: var(--line-strong); box-shadow: 0 14px 30px rgba(18,38,68,.09); }
.icon-button:active { transform: translateY(0) scale(.94); }

/* ---------- Hero ---------- */
.hero {
  position: relative;
  min-height: max(720px, 94vh);
  padding: calc(var(--header-h) + 64px) 24px 74px;
  display: grid;
  align-items: center;
  overflow: hidden;
  isolation: isolate;
}
.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -3;
  background:
    linear-gradient(rgba(49,95,205,.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(49,95,205,.035) 1px, transparent 1px);
  background-size: 54px 54px;
  mask-image: linear-gradient(to bottom, rgba(0,0,0,.25), transparent 70%);
  opacity: .7;
}
.hero::after {
  content: "";
  position: absolute;
  z-index: -2;
  width: 900px;
  height: 580px;
  right: -220px;
  top: 84px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(49,95,205,.10), transparent 67%);
  filter: blur(8px);
}
.hero-inner {
  width: min(var(--max), 100%);
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(0, .88fr) minmax(500px, 1.12fr);
  align-items: center;
  gap: clamp(54px, 7vw, 110px);
}
.hero-copy { position: relative; z-index: 3; }
.hero-eyebrow {
  margin: 0 0 22px;
  color: var(--blue-2);
  font: 700 11.5px/1.4 var(--sans);
  letter-spacing: .17em;
  text-transform: uppercase;
}
.hero-name-cn {
  margin: 0;
  color: var(--ink);
  font: 600 clamp(64px, 7.2vw, 104px)/.95 var(--serif);
  letter-spacing: .06em;
}
.hero-name-en {
  margin: 13px 0 0;
  color: var(--ink-soft);
  font: 540 clamp(31px, 3.2vw, 47px)/1.05 var(--serif);
  letter-spacing: .015em;
}
.hero-rule {
  width: 42px;
  height: 2px;
  margin: 28px 0 20px;
  background: var(--blue);
  transform-origin: left;
}
.hero-role {
  margin: 0;
  color: var(--ink-soft);
  font-weight: 680;
  line-height: 1.75;
}
.hero-institute {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  margin-top: 5px;
  color: var(--muted);
  font-size: 14px;
  transition: color .22s ease;
}
.hero-institute svg { width: 14px; height: 14px; fill: none; stroke: currentColor; stroke-width: 1.7; transition: transform .22s var(--ease); }
.hero-institute:hover { color: var(--blue); }
.hero-institute:hover svg { transform: translate(2px,-2px); }
.hero-focus {
  margin: 32px 0 7px;
  color: var(--blue);
  font-size: 16px;
  font-weight: 760;
  letter-spacing: .015em;
}
.hero-keywords {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.8;
}
.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 34px;
}
.button {
  --mx: 0px;
  --my: 0px;
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 46px;
  padding: 0 20px;
  border: 1px solid var(--line-strong);
  border-radius: 12px;
  overflow: hidden;
  color: var(--ink);
  background: transparent;
  font-size: 13px;
  font-weight: 700;
  transform: translate(var(--mx),var(--my));
  transition: transform .18s var(--ease), box-shadow .25s ease, border-color .25s ease, background .25s ease, color .25s ease;
}
.button::before {
  content: "";
  position: absolute;
  width: 90px;
  height: 90px;
  left: -100px;
  top: -22px;
  border-radius: 50%;
  background: rgba(255,255,255,.25);
  transition: left .55s var(--ease);
}
.button:hover::before { left: calc(100% + 18px); }
.button:hover { transform: translate(var(--mx), calc(var(--my) - 2px)); box-shadow: 0 16px 34px rgba(18,38,68,.12); border-color: var(--blue-2); }
.button:active { transform: translate(var(--mx), var(--my)) scale(.98); }
.button-primary { color: #fff; border-color: #163879; background: linear-gradient(135deg, #173d8d, #244d9d); box-shadow: 0 12px 28px rgba(23,61,141,.18); }
.button-primary svg,
.button-secondary svg { width: 15px; height: 15px; fill: none; stroke: currentColor; stroke-width: 1.8; transition: transform .22s var(--ease); }
.button:hover svg { transform: translateX(3px); }

.hero-visual {
  position: relative;
  min-height: 550px;
  display: grid;
  place-items: center;
  perspective: 1400px;
  isolation: isolate;
}
.research-visual-heading {
  position: absolute;
  left: 18px;
  top: 18px;
  z-index: 4;
  display: grid;
  gap: 3px;
  pointer-events: none;
}
.research-visual-heading span {
  color: var(--muted-2);
  font: 700 9.5px/1.2 var(--mono);
  letter-spacing: .15em;
}
.research-visual-heading strong {
  color: var(--ink-soft);
  font: 650 12px/1.4 var(--sans);
  letter-spacing: .02em;
}
.spatial-stage {
  --rx: 0deg;
  --ry: 0deg;
  --tx: 0px;
  --ty: 0px;
  position: relative;
  width: min(100%, 760px);
  aspect-ratio: 1.34;
  transform-style: preserve-3d;
  transform: translate3d(var(--tx),var(--ty),0) rotateX(var(--rx)) rotateY(var(--ry));
  transition: transform .58s var(--ease-soft), filter .35s ease;
  filter: drop-shadow(0 38px 50px rgba(31,65,130,.065));
}
.spatial-svg { width: 100%; height: 100%; overflow: visible; }
.spatial-svg .research-layer {
  transform-origin: center;
  transition: opacity .42s ease, filter .42s ease, transform .42s var(--ease);
}
.spatial-svg [tabindex="0"] { outline: none; cursor: default; }

/* Scientific figure: plateau / virtual space */
.plateau-terrain { opacity: .76; }
.plateau-ridge {
  fill: none;
  stroke: var(--ink-soft);
  stroke-width: 1.15;
  stroke-opacity: .18;
}
.terrain-contour {
  fill: none;
  stroke: var(--blue-2);
  stroke-opacity: .12;
  stroke-width: 1;
}
.contour-2 { stroke-opacity: .10; }
.contour-3 { stroke-opacity: .09; }
.contour-4 { stroke-opacity: .075; }
.virtual-trail {
  fill: none;
  stroke: var(--gold);
  stroke-width: 1.4;
  stroke-opacity: .32;
  stroke-dasharray: 3 7;
}
.spatial-label {
  fill: var(--muted);
  font: 650 11.5px/1 var(--sans);
  letter-spacing: .02em;
}
.spatial-label-small,
.spatial-label-tiny {
  fill: var(--muted-2);
  font: 600 9.2px/1 var(--mono);
  letter-spacing: .065em;
}
.poi { cursor: pointer !important; }
.poi-hit { fill: transparent; pointer-events: all; }
.poi-dot {
  fill: var(--paper-2);
  stroke: var(--blue-2);
  stroke-width: 2;
  transition: r .22s var(--ease), fill .22s ease, filter .22s ease;
}
.poi-mark { fill: none; stroke: var(--gold); stroke-width: 1.3; stroke-linecap: round; stroke-linejoin: round; }
.poi text { fill: var(--muted-2); font: 600 9px/1 var(--mono); transition: fill .22s ease; }
.poi:hover .poi-dot,
.poi:focus .poi-dot { r: 7px; fill: var(--blue-2); filter: drop-shadow(0 0 7px rgba(49,95,205,.28)); }
.poi:hover text,
.poi:focus text { fill: var(--blue); }

/* Virtual / physical paths */
.virtual-route,
.physical-route,
.physical-route-secondary,
.interactive-route,
.virtual-route-glow,
.physical-route-glow,
.space-correspondence,
.guide-link {
  fill: none;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.virtual-route-glow {
  stroke: var(--blue-2);
  stroke-width: 18;
  stroke-opacity: .045;
}
.virtual-route {
  stroke: var(--blue-2);
  stroke-width: 2.8;
  filter: drop-shadow(0 0 7px rgba(49,95,205,.18));
}
.interactive-route {
  stroke: var(--blue-2);
  stroke-width: 2.2;
  stroke-dasharray: 5 6;
  stroke-opacity: 0;
  transition: stroke-opacity .28s ease;
}
.spatial-stage.is-poi-hover .interactive-route { stroke-opacity: .88; }
.physical-route-glow {
  stroke: var(--gold);
  stroke-width: 16;
  stroke-opacity: .038;
}
.physical-route {
  stroke: var(--gold);
  stroke-width: 2.2;
  stroke-opacity: .82;
}
.physical-route-secondary {
  stroke: var(--muted);
  stroke-width: 1.25;
  stroke-opacity: .34;
  stroke-dasharray: 3 6;
}
.path-draw {
  stroke-dasharray: var(--path-length, 1000);
  stroke-dashoffset: var(--path-length, 1000);
  animation: pathDraw 1.8s .32s var(--ease) forwards;
}
.physical-route.path-draw { animation-delay: .52s; }
@keyframes pathDraw { to { stroke-dashoffset: 0; } }
.path-label { fill: var(--muted-2); font: 600 8.5px/1 var(--mono); letter-spacing: .05em; }

/* Physical room */
.physical-floor {
  fill: color-mix(in srgb, var(--blue-soft) 38%, transparent);
  stroke: none;
}
.physical-boundary {
  fill: none;
  stroke: var(--ink-soft);
  stroke-width: 1.3;
  stroke-opacity: .24;
}
.physical-grid {
  fill: none;
  stroke: var(--blue-2);
  stroke-width: .9;
  stroke-opacity: .075;
}

/* Users and cross-space correspondence */
.user-ring,
.virtual-user-ring {
  fill: color-mix(in srgb, var(--paper-2) 88%, transparent);
  stroke: var(--blue-2);
  stroke-width: 1.2;
  stroke-opacity: .42;
}
.user-core,
.virtual-user-core { fill: var(--blue-2); }
.user-core-b { fill: var(--gold); }
.user-heading {
  fill: none;
  stroke: var(--blue-2);
  stroke-width: 1.25;
  stroke-linecap: round;
}
.physical-user-b .user-heading { stroke: var(--gold); }
.physical-user text { fill: var(--muted); font: 700 8.5px/1 var(--mono); }
.virtual-user-ring { stroke-opacity: .32; }
.space-correspondence {
  stroke: var(--blue-2);
  stroke-width: .9;
  stroke-opacity: .14;
  stroke-dasharray: 3 6;
}

/* Prediction / risk */
.layer-prediction { opacity: .26; }
.prediction ellipse {
  fill: var(--blue-soft);
  stroke: var(--blue-2);
  stroke-width: 1;
  stroke-opacity: .26;
  stroke-dasharray: 4 6;
}
.prediction-b ellipse { fill: var(--gold-soft); stroke: var(--gold); }
.prediction path { fill: none; stroke: var(--blue-2); stroke-width: 1.1; stroke-opacity: .36; }
.prediction-b path { stroke: var(--gold); }
.risk-zone {
  --risk: 0;
  opacity: calc(.12 + var(--risk) * .78);
  transition: opacity .18s ease;
  color: #c07b45;
}
.risk-halo { fill: url(#riskGradient); }
.risk-dot { fill: var(--gold); opacity: calc(.2 + var(--risk) * .8); }
.risk-zone text { fill: var(--gold); font: 650 8.5px/1 var(--mono); opacity: calc(.2 + var(--risk) * .8); }

/* Guide agent */
.layer-agent { opacity: .42; }
.guide-link {
  stroke: var(--blue-2);
  stroke-width: 1.15;
  stroke-opacity: .28;
  stroke-dasharray: 4 6;
}
.agent-orbit { fill: var(--blue-soft); stroke: var(--blue-2); stroke-width: 1; stroke-opacity: .26; }
.agent-core { fill: var(--paper-2); stroke: var(--blue-2); stroke-width: 2; }
.agent-heading { fill: none; stroke: var(--blue-2); stroke-width: 1.4; stroke-linecap: round; }
.agent-marker { transform-box: fill-box; transform-origin: center; animation: agentFloat 3.6s ease-in-out infinite; }
@keyframes agentFloat { 0%,100% { translate: 0 0; } 50% { translate: 0 -4px; } }

/* Dynamic pointer constraint */
.avoid-region { opacity: 0; pointer-events: none; transition: opacity .24s ease; }
.avoid-region circle:first-child {
  fill: var(--gold-soft);
  stroke: var(--gold);
  stroke-width: 1;
  stroke-opacity: .34;
  stroke-dasharray: 4 6;
}
.avoid-region circle:nth-child(2) { fill: var(--gold); opacity: .55; }
.avoid-region text { fill: var(--gold); font: 600 8.2px/1 var(--mono); }
.spatial-stage.has-dynamic-constraint .avoid-region { opacity: .82; }

/* Layer storytelling: subtle emphasis, never dashboard-like */
.spatial-stage[data-stage="understand"] .layer-space { opacity: 1; filter: saturate(1.04); }
.spatial-stage[data-stage="understand"] .layer-prediction { opacity: .15; }
.spatial-stage[data-stage="understand"] .layer-agent { opacity: .22; }
.spatial-stage[data-stage="predict"] .layer-prediction { opacity: .92; }
.spatial-stage[data-stage="predict"] .layer-space { opacity: .62; }
.spatial-stage[data-stage="predict"] .layer-agent { opacity: .24; }
.spatial-stage[data-stage="guide"] .layer-agent { opacity: 1; filter: drop-shadow(0 0 8px rgba(49,95,205,.16)); }
.spatial-stage[data-stage="guide"] .layer-prediction { opacity: .48; }
.spatial-stage[data-stage="redirect"] .layer-redirect { opacity: 1; filter: saturate(1.08); }
.spatial-stage[data-stage="redirect"] .virtual-route,
.spatial-stage[data-stage="redirect"] .physical-route { stroke-width: 3; }
.spatial-stage[data-stage="redirect"] .layer-prediction { opacity: .22; }
.spatial-stage[data-focus] .research-layer { opacity: .16; filter: none; }
.spatial-stage[data-focus="space"] .layer-space,
.spatial-stage[data-focus="prediction"] .layer-prediction,
.spatial-stage[data-focus="agent"] .layer-agent,
.spatial-stage[data-focus="redirect"] .layer-redirect,
.spatial-stage[data-focus="users"] .layer-users { opacity: 1; filter: saturate(1.06); }
.spatial-stage.has-dynamic-constraint .layer-redirect { opacity: 1 !important; }

.research-legend text { fill: var(--muted-2); font: 600 8.5px/1 var(--mono); }
.legend-virtual { stroke: var(--blue-2); stroke-width: 2.2; }
.legend-physical { stroke: var(--gold); stroke-width: 2; stroke-dasharray: 2 5; }

/* Caption and lightweight controls */
.research-visual-caption {
  position: absolute;
  left: 20px;
  top: 54px;
  bottom: auto;
  z-index: 5;
  width: min(330px, 54%);
  display: grid;
  gap: 3px;
  padding-left: 14px;
  border-left: 2px solid var(--blue-2);
  pointer-events: none;
  transition: opacity .25s ease, transform .3s var(--ease);
}
.visual-step {
  color: var(--blue-2);
  font: 700 9px/1.2 var(--mono);
  letter-spacing: .12em;
}
.research-visual-caption strong {
  color: var(--ink);
  font: 700 13px/1.45 var(--sans);
}
.research-visual-caption > span:last-child {
  color: var(--muted);
  font: 500 10.8px/1.55 var(--sans);
}
.research-stage-nav {
  position: absolute;
  right: 16px;
  bottom: 42px;
  z-index: 6;
  display: flex;
  gap: 12px;
}
.research-stage-button {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 4px 0 5px;
  border: 0;
  border-bottom: 1px solid transparent;
  color: var(--muted-2);
  background: transparent;
  cursor: pointer;
  font: 650 8.3px/1 var(--mono);
  letter-spacing: .04em;
  transition: color .22s ease, border-color .22s ease, transform .22s var(--ease);
}
.research-stage-button span { font-size: 7.5px; opacity: .65; }
.research-stage-button:hover,
.research-stage-button:focus-visible,
.research-stage-button.is-active {
  color: var(--blue);
  border-color: var(--blue-2);
  transform: translateY(-1px);
  outline: none;
}
.research-visual-hint {
  position: absolute;
  right: 18px;
  top: 52px;
  z-index: 5;
  color: var(--muted-2);
  font: 600 8.8px/1.3 var(--mono);
  letter-spacing: .055em;
  transition: opacity .5s ease, transform .5s var(--ease);
  pointer-events: none;
}
.research-visual-hint.is-muted { opacity: .42; }
.research-visual-hint.is-hidden { opacity: 0; transform: translateY(-4px); }

.hero-scroll-cue {
  position: absolute;
  left: 50%;
  bottom: 28px;
  transform: translateX(-50%);
  display: grid;
  justify-items: center;
  gap: 7px;
  color: var(--muted-2);
  font: 600 10px/1 var(--mono);
  letter-spacing: .15em;
  text-transform: uppercase;
}
.hero-scroll-cue span {
  width: 1px;
  height: 34px;
  background: linear-gradient(var(--blue-2), transparent);
  transform-origin: top;
  animation: cue 1.8s ease-in-out infinite;
}
@keyframes cue { 0%,100% { transform: scaleY(.45); opacity: .35; } 50% { transform: scaleY(1); opacity: 1; } }

/* ---------- Main content ---------- */
.content-shell {
  position: relative;
  width: min(var(--max), calc(100% - 48px));
  margin: 0 auto;
}
.section-block {
  position: relative;
  scroll-margin-top: calc(var(--header-h) + 26px);
  padding: 92px 0 100px;
  border-top: 1px solid var(--line);
}
.section-block:first-child { border-top: 0; }
.section-grid {
  display: grid;
  grid-template-columns: 176px minmax(0,1fr);
  gap: clamp(36px, 6vw, 86px);
}
.section-marker { position: relative; }
.section-number {
  position: sticky;
  top: calc(var(--header-h) + 42px);
  display: inline-grid;
  gap: 9px;
  color: var(--blue);
  font: 700 12px/1 var(--mono);
  letter-spacing: .08em;
}
.section-number::after {
  content: "";
  width: 32px;
  height: 2px;
  background: var(--blue-2);
}
.section-main { min-width: 0; }
.section-heading-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 44px;
}
.section-title {
  margin: 0;
  font: 650 clamp(28px, 3vw, 42px)/1.08 var(--serif);
  letter-spacing: .02em;
}
.section-title-en {
  color: var(--muted-2);
  font: 600 10.5px/1.2 var(--mono);
  letter-spacing: .13em;
  text-transform: uppercase;
}
.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity .68s var(--ease), transform .68s var(--ease);
}
.reveal.is-visible { opacity: 1; transform: translateY(0); }
.reveal-stagger > * {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity .62s var(--ease), transform .62s var(--ease);
}
.reveal-stagger.is-visible > * { opacity: 1; transform: translateY(0); }
.reveal-stagger.is-visible > *:nth-child(2) { transition-delay: .055s; }
.reveal-stagger.is-visible > *:nth-child(3) { transition-delay: .11s; }
.reveal-stagger.is-visible > *:nth-child(4) { transition-delay: .165s; }
.reveal-stagger.is-visible > *:nth-child(5) { transition-delay: .22s; }
.reveal-stagger.is-visible > *:nth-child(6) { transition-delay: .275s; }
.reveal-stagger.is-visible > *:nth-child(7) { transition-delay: .33s; }
.reveal-stagger.is-visible > *:nth-child(8) { transition-delay: .385s; }

/* About */
.about-layout {
  display: grid;
  grid-template-columns: minmax(220px, 310px) minmax(0, 1fr);
  gap: clamp(38px, 6vw, 78px);
  align-items: start;
}
.portrait-frame {
  position: relative;
  overflow: hidden;
  aspect-ratio: .76;
  border-radius: 2px;
  background: var(--paper-3);
  box-shadow: 0 20px 65px rgba(18,38,68,.09);
  transform: translateZ(0);
}
.portrait-frame::after {
  content: "QINGHAI";
  position: absolute;
  left: 16px;
  bottom: 14px;
  padding: 5px 8px;
  color: rgba(255,255,255,.88);
  background: rgba(10,22,42,.42);
  backdrop-filter: blur(9px);
  font: 700 9px/1 var(--mono);
  letter-spacing: .18em;
}
.portrait-frame img { width: 100%; height: 100%; object-fit: cover; object-position: 50% 37%; transition: transform 1.1s var(--ease); }
.portrait-frame:hover img { transform: scale(1.025); }
.about-copy { max-width: 750px; }
.about-intro {
  margin: 0;
  color: var(--ink-soft);
  font-size: clamp(16px, 1.35vw, 18px);
  line-height: 2.02;
}
.about-meta {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0 34px;
  margin-top: 38px;
  border-top: 1px solid var(--line);
}
.meta-row { padding: 18px 0; border-bottom: 1px solid var(--line); }
.meta-label { display: block; margin-bottom: 7px; color: var(--muted-2); font: 700 9.5px/1.2 var(--mono); letter-spacing: .13em; text-transform: uppercase; }
.meta-value { color: var(--ink-soft); font-size: 13.5px; line-height: 1.72; }
.meta-value a { color: var(--blue); }
.inline-arrow { display: inline-block; margin-left: 4px; transition: transform .22s var(--ease); }
a:hover .inline-arrow { transform: translate(2px,-2px); }

/* Timelines */
.timeline-list { list-style: none; margin: 0; padding: 0; }
.timeline-item {
  position: relative;
  display: grid;
  grid-template-columns: minmax(175px, 225px) 26px minmax(0,1fr);
  min-height: 108px;
}
.timeline-when { padding: 2px 20px 28px 0; color: var(--muted); font: 620 12px/1.5 var(--mono); text-align: right; }
.timeline-track { position: relative; }
.timeline-track::before { content: ""; position: absolute; left: 50%; top: 4px; bottom: -4px; width: 1px; background: var(--line-strong); transform: translateX(-50%); }
.timeline-item:last-child .timeline-track::before { bottom: 78%; }
.timeline-dot { position: absolute; left: 50%; top: 4px; width: 10px; height: 10px; border: 2px solid var(--blue-2); border-radius: 50%; background: var(--paper); transform: translateX(-50%); box-shadow: 0 0 0 5px var(--blue-soft); transition: transform .24s var(--ease), background .24s ease; }
.timeline-item:hover .timeline-dot { transform: translateX(-50%) scale(1.25); background: var(--blue-2); }
.timeline-what { padding: 0 0 28px 20px; color: var(--ink-soft); font-size: 15px; line-height: 1.8; }
.timeline-what strong { color: var(--ink); }

/* Editorial list: projects, teaching projects, courses, awards */
.editorial-list { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--line); }
.editorial-item {
  position: relative;
  display: grid;
  grid-template-columns: 72px minmax(0,1fr) auto;
  gap: 26px;
  padding: 24px 8px 24px 0;
  border-bottom: 1px solid var(--line);
  transition: padding .3s var(--ease), background .25s ease;
}
.editorial-item::before {
  content: "";
  position: absolute;
  left: 0;
  top: -1px;
  width: 0;
  height: 2px;
  background: var(--blue-2);
  transition: width .45s var(--ease);
}
.editorial-item:hover { padding-left: 10px; padding-right: 12px; background: linear-gradient(90deg,var(--blue-faint),transparent 80%); }
.editorial-item:hover::before { width: 52px; }
.editorial-index { color: var(--muted-2); font: 650 11px/1.8 var(--mono); letter-spacing: .04em; }
.editorial-body { min-width: 0; }
.editorial-title { display: block; color: var(--ink); font-size: 15.5px; font-weight: 730; line-height: 1.65; }
.editorial-detail { display: block; margin-top: 5px; color: var(--muted); font-size: 13.5px; line-height: 1.78; }
.editorial-tag {
  align-self: start;
  margin-top: 2px;
  padding: 5px 8px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--blue);
  font: 700 9.5px/1 var(--mono);
  white-space: nowrap;
  transition: transform .22s var(--ease), border-color .22s ease;
}
.editorial-item:hover .editorial-tag { transform: translateY(-1px); border-color: var(--line-strong); }

/* Publications */
.publication-toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: -18px 0 34px;
}
.year-filter {
  min-width: 58px;
  height: 34px;
  padding: 0 11px;
  border: 1px solid transparent;
  border-radius: 999px;
  color: var(--muted);
  background: transparent;
  font: 650 11px/1 var(--mono);
  cursor: pointer;
  transition: color .2s ease, background .2s ease, border-color .2s ease, transform .2s var(--ease);
}
.year-filter:hover { color: var(--ink); transform: translateY(-1px); }
.year-filter.is-active { color: var(--blue); border-color: var(--line); background: var(--blue-soft); }
.publication-year { display: grid; grid-template-columns: 86px minmax(0,1fr); gap: 22px; padding-top: 10px; }
.publication-year + .publication-year { margin-top: 34px; }
.publication-year-label { position: sticky; top: calc(var(--header-h) + 34px); align-self: start; color: var(--blue); font: 700 18px/1.1 var(--serif); }
.pub-list { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--line); }
.pub-item {
  position: relative;
  padding: 20px 18px 21px 38px;
  border-bottom: 1px solid var(--line);
  transition: background .24s ease, transform .28s var(--ease), opacity .25s ease;
}
.pub-item::before {
  content: attr(data-number);
  position: absolute;
  left: 0;
  top: 23px;
  color: var(--muted-2);
  font: 650 10px/1 var(--mono);
}
.pub-item::after {
  content: "";
  position: absolute;
  left: 0;
  top: -1px;
  width: 0;
  height: 2px;
  background: var(--blue-2);
  transition: width .42s var(--ease);
}
.pub-list:hover .pub-item:not(:hover) { opacity: .56; }
.pub-item:hover { background: linear-gradient(90deg,var(--blue-faint),transparent 88%); transform: translateX(5px); }
.pub-item:hover::after { width: 34px; }
.pub-authors { color: var(--muted); font-size: 12.8px; line-height: 1.7; }
.pub-title { display: block; margin-top: 4px; color: var(--ink); font-size: 15.2px; font-weight: 720; line-height: 1.62; }
.pub-info { display: block; margin-top: 4px; color: var(--ink-soft); font-size: 12.8px; line-height: 1.68; }
.pub-doi { display: block; margin-top: 6px; color: var(--muted-2); font: 500 10.5px/1.6 var(--mono); word-break: break-word; }
.pub-doi a { color: var(--blue); }
.pub-item .self { color: var(--blue); font-weight: 780; text-decoration: none; }
.pub-item .venue { font-weight: 720; }
.publication-year.is-filtered-out { display: none; }

/* Courses */
.course-list { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--line); counter-reset: courses; }
.course-item {
  counter-increment: courses;
  display: grid;
  grid-template-columns: 70px minmax(0,1fr) 36px;
  align-items: center;
  gap: 22px;
  min-height: 86px;
  border-bottom: 1px solid var(--line);
  transition: padding .3s var(--ease), background .25s ease;
}
.course-item::before { content: counter(courses, decimal-leading-zero); color: var(--muted-2); font: 650 10px/1 var(--mono); }
.course-item:hover { padding: 0 12px; background: linear-gradient(90deg,var(--blue-faint),transparent); }
.course-name { font: 600 clamp(16px, 1.6vw, 20px)/1.45 var(--serif); }
.course-icon { color: var(--blue-2); opacity: .65; transition: transform .25s var(--ease), opacity .25s ease; }
.course-item:hover .course-icon { transform: translateX(4px); opacity: 1; }

/* Contact / footer */
.contact-panel {
  position: relative;
  overflow: hidden;
  padding: clamp(34px, 5vw, 68px);
  border: 1px solid var(--line);
  background:
    linear-gradient(120deg, color-mix(in srgb,var(--surface-strong) 90%,transparent), color-mix(in srgb,var(--surface) 55%,transparent)),
    radial-gradient(540px 260px at 85% 30%, var(--blue-soft), transparent 70%);
  box-shadow: var(--shadow-soft);
  transform-style: preserve-3d;
}
.contact-panel::after {
  content: "";
  position: absolute;
  right: -80px;
  bottom: -120px;
  width: 360px;
  height: 360px;
  border: 1px solid var(--line);
  border-radius: 50%;
  box-shadow: 0 0 0 42px var(--blue-faint), 0 0 0 84px rgba(49,95,205,.018);
  pointer-events: none;
}
.contact-kicker { color: var(--blue); font: 700 10px/1 var(--mono); letter-spacing: .15em; text-transform: uppercase; }
.contact-title { max-width: 680px; margin: 14px 0 24px; font: 560 clamp(34px, 4.2vw, 58px)/1.12 var(--serif); }
.contact-links { display: flex; flex-wrap: wrap; gap: 10px 22px; margin-top: 28px; }
.contact-link,
.copy-email {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 7px 0;
  border: 0;
  color: var(--ink-soft);
  background: none;
  cursor: pointer;
  font-size: 13.5px;
}
.contact-link::after,
.copy-email::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 2px;
  height: 1px;
  background: var(--blue-2);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform .28s var(--ease);
}
.contact-link:hover::after,
.copy-email:hover::after { transform: scaleX(1); }
.contact-note { max-width: 720px; margin-top: 28px; color: var(--muted); font-size: 13.5px; line-height: 1.8; }
.footer-mark {
  display: grid;
  grid-template-columns: 230px minmax(0,1fr) auto;
  align-items: center;
  gap: 26px;
  padding: 42px 0 26px;
  color: var(--muted-2);
  font-size: 11px;
}
.footer-logo { width: 205px; max-height: 62px; object-fit: contain; object-position: left center; }
html[data-theme="dark"] .footer-logo { filter: brightness(1.4) saturate(.92); }
.footer-institute { color: var(--muted); }
.footer-institute:hover { color: var(--blue); }

/* ---------- Section rail ---------- */
.section-rail {
  position: fixed;
  right: max(18px, calc((100vw - var(--max))/2 - 52px));
  top: 50%;
  z-index: 120;
  display: grid;
  gap: 10px;
  transform: translateY(-50%);
}
.rail-link {
  position: relative;
  width: 34px;
  height: 18px;
  display: grid;
  place-items: center;
}
.rail-link::before {
  content: "";
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--muted-2);
  transition: transform .22s var(--ease), background .22s ease, box-shadow .22s ease;
}
.rail-link span {
  position: absolute;
  right: 28px;
  top: 50%;
  padding: 5px 8px;
  border: 1px solid var(--line);
  border-radius: 6px;
  color: var(--ink-soft);
  background: var(--surface-strong);
  box-shadow: 0 10px 30px rgba(18,38,68,.09);
  font: 650 10px/1 var(--sans);
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  transform: translate(5px,-50%);
  transition: opacity .18s ease, transform .2s var(--ease);
}
.rail-link:hover span { opacity: 1; transform: translate(0,-50%); }
.rail-link:hover::before { transform: scale(1.45); background: var(--blue-2); }
.rail-link[aria-current="page"]::before { transform: scale(1.5); background: var(--blue-2); box-shadow: 0 0 0 5px var(--blue-soft); }

.to-top {
  position: fixed;
  right: 24px;
  bottom: 24px;
  z-index: 220;
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  opacity: 0;
  pointer-events: none;
  transform: translateY(10px);
}
.to-top.show { opacity: 1; pointer-events: auto; transform: translateY(0); }
.to-top:hover { transform: translateY(-3px); border-color: var(--line-strong); box-shadow: 0 18px 36px rgba(18,38,68,.12); }
.to-top svg { width: 19px; height: 19px; fill: none; stroke: currentColor; stroke-width: 1.7; }
.toast {
  position: fixed;
  left: 50%;
  bottom: 28px;
  z-index: 500;
  padding: 9px 14px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--ink-soft);
  background: var(--surface-strong);
  box-shadow: var(--shadow-soft);
  backdrop-filter: blur(16px);
  opacity: 0;
  pointer-events: none;
  transform: translate(-50%,12px);
  transition: opacity .22s ease, transform .28s var(--ease);
  font-size: 12px;
}
.toast.show { opacity: 1; transform: translate(-50%,0); }

/* ---------- Responsive ---------- */
@media (max-width: 1180px) {
  .header-inner { grid-template-columns: 190px minmax(0,1fr) 40px; gap: 15px; }
  .institution-logo-frame { width: 184px; }
  .nav-links { gap: 9px; }
  .nav-link { font-size: 11.5px; }
  .section-rail { display: none; }
}

@media (max-width: 980px) {
  :root { --header-h: 68px; }
  .header-inner { width: min(100% - 32px, var(--max)); grid-template-columns: 190px 1fr 40px; }
  .primary-nav { justify-self: end; }
  .nav-toggle {
    position: relative;
    display: grid;
    align-content: center;
    gap: 5px;
    width: 40px;
    height: 40px;
    padding: 0 9px;
    border: 1px solid var(--line);
    border-radius: 50%;
    background: var(--surface-strong);
    cursor: pointer;
  }
  .nav-toggle span:not(.sr-only) { display: block; width: 100%; height: 1px; background: currentColor; transition: transform .25s var(--ease); }
  .nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(3px) rotate(45deg); }
  .nav-toggle[aria-expanded="true"] span:nth-child(2) { transform: translateY(-3px) rotate(-45deg); }
  .nav-links {
    position: fixed;
    left: 16px;
    right: 16px;
    top: calc(var(--header-h) + 8px);
    display: grid;
    grid-template-columns: repeat(3,1fr);
    gap: 0;
    padding: 12px;
    border: 1px solid var(--line);
    border-radius: 16px;
    background: var(--surface-strong);
    box-shadow: var(--shadow-float);
    backdrop-filter: blur(24px);
    opacity: 0;
    pointer-events: none;
    transform: translateY(-8px) scale(.985);
    transform-origin: top right;
    transition: opacity .22s ease, transform .28s var(--ease);
  }
  .nav-links.is-open { opacity: 1; pointer-events: auto; transform: translateY(0) scale(1); }
  .nav-link { justify-content: center; min-height: 42px; font-size: 12px; }
  .header-tools { justify-self: end; }
  .hero { min-height: auto; padding-top: calc(var(--header-h) + 70px); }
  .hero-inner { grid-template-columns: 1fr; gap: 48px; }
  .hero-copy { max-width: 650px; }
  .hero-visual { min-height: 430px; }
  .spatial-stage { max-width: 720px; }
  .hero-scroll-cue { display: none; }
  .section-grid { grid-template-columns: 70px minmax(0,1fr); gap: 34px; }
}

@media (max-width: 720px) {
  .header-inner { width: calc(100% - 24px); grid-template-columns: minmax(0,160px) 1fr 38px; gap: 8px; }
  .institution-logo-frame { width: 154px; height: 46px; }
  .nav-links { grid-template-columns: repeat(2,1fr); }
  .hero { padding-left: 18px; padding-right: 18px; }
  .hero-name-cn { font-size: clamp(52px, 17vw, 74px); }
  .hero-name-en { font-size: 31px; }
  .hero-visual { min-height: 340px; }
  .content-shell { width: calc(100% - 30px); }
  .section-block { padding: 72px 0 78px; }
  .section-grid { grid-template-columns: 1fr; gap: 20px; }
  .section-marker { height: 22px; }
  .section-number { position: static; display: flex; align-items: center; gap: 10px; }
  .section-number::after { width: 26px; }
  .section-heading-row { margin-bottom: 32px; }
  .section-title-en { display: none; }
  .about-layout { grid-template-columns: 1fr; }
  .portrait-frame { max-width: 290px; }
  .about-meta { grid-template-columns: 1fr; }
  .timeline-item { grid-template-columns: 1fr 24px; min-height: auto; }
  .timeline-when { grid-column: 1; text-align: left; padding: 0 12px 6px 0; }
  .timeline-track { grid-column: 2; grid-row: 1 / span 2; }
  .timeline-what { grid-column: 1; padding: 0 12px 30px 0; }
  .editorial-item { grid-template-columns: 44px minmax(0,1fr); gap: 16px; }
  .editorial-tag { grid-column: 2; justify-self: start; }
  .publication-year { grid-template-columns: 1fr; gap: 7px; }
  .publication-year-label { position: static; padding-bottom: 7px; }
  .course-item { grid-template-columns: 44px minmax(0,1fr) 26px; gap: 12px; }
  .footer-mark { grid-template-columns: 1fr; }
  .footer-logo { width: 200px; }
}

@media (max-width: 480px) {
  body { font-size: 15px; }
  .institution-logo-frame { width: 142px; }
  .header-inner { grid-template-columns: minmax(0,146px) 1fr 36px; }
  .icon-button, .nav-toggle { width: 36px; height: 36px; }
  .hero { padding-top: 116px; padding-bottom: 56px; }
  .hero-actions { display: grid; grid-template-columns: 1fr; }
  .button { width: 100%; }
  .hero-visual { min-height: 290px; }
  .contact-panel { padding: 30px 22px; }
  .publication-toolbar { margin-top: 0; }
  .pub-item { padding-right: 5px; }
}

/* ---------- Reduced motion / keyboard ---------- */
:focus-visible {
  outline: 2px solid var(--blue-2);
  outline-offset: 4px;
  border-radius: 4px;
}

@media (max-width: 980px) {
  .research-visual-heading { left: 10px; top: 8px; }
  .research-visual-caption { left: 12px; top: 46px; bottom: auto; width: min(330px, 62%); }
  .research-stage-nav { right: 8px; bottom: 36px; gap: 8px; }
}
@media (max-width: 680px) {
  .research-visual-heading { display: none; }
  .research-visual-caption { left: 4px; top: 24px; bottom: auto; width: 70%; }
  .research-stage-nav { display: none; }
  .research-visual-hint { right: 4px; top: 14px; }
  .research-legend { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    scroll-behavior: auto !important;
    transition-duration: .001ms !important;
  }
  .reveal,
  .reveal-stagger > * { opacity: 1 !important; transform: none !important; }
  .spatial-stage { transform: none !important; }
  .path-draw, .agent-marker, .hero-scroll-cue span { animation: none !important; }
  .layer-prediction, .layer-agent { opacity: .68; }
  .research-visual-hint { display: none; }
}