/* Ivory light design (2026-11-10): Apple-style surfaces and pill buttons,
   serif headings, system sans body, pixel nameplate kept as the banner. */
:root {
  --bg: #fbfbfd;
  --surface: #ffffff;
  --card: #f5f5f7;
  --ink: #1d1d1f;
  --text: #333336;
  --muted: #6e6e73;
  --line: #d2d2d7;
  --hair: #e8e8ed;
  --blue: #0071e3;
  --link: #0066cc;
  --radius: 18px;
  --serif: "Iowan Old Style", "Charter", "Source Han Serif SC", "Noto Serif SC", "Songti SC", "STSong", Georgia, serif;
  --sans: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 72px; }
body { margin: 0; background: var(--bg); color: var(--text); font-family: var(--sans); font-size: 16px; line-height: 1.7; -webkit-font-smoothing: antialiased; }
h1, h2, h3, h4, p, figure, ul { margin: 0; }
ul { padding: 0; list-style: none; }
img, video, iframe { max-width: 100%; }
a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }
a:focus-visible, button:focus-visible, video:focus-visible { outline: 2px solid var(--blue); outline-offset: 3px; border-radius: 6px; }
html[data-lang="en"] .zh, html[data-lang="zh"] .en { display: none !important; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0; }
strong { color: var(--ink); font-weight: 600; }

/* Navigation */
.nav { position: sticky; top: 0; z-index: 10; background: rgba(251,251,253,.82); backdrop-filter: saturate(180%) blur(20px); -webkit-backdrop-filter: saturate(180%) blur(20px); border-bottom: 1px solid var(--hair); }
.nav-inner { width: min(1120px, calc(100% - 48px)); margin: 0 auto; height: 52px; display: flex; align-items: center; gap: 28px; }
.wordmark { font-family: var(--serif); font-size: 18px; color: var(--ink); font-weight: 600; letter-spacing: -.01em; }
.wordmark:hover { text-decoration: none; }
.nav nav { display: flex; gap: 24px; margin-left: auto; font-size: 13px; }
.nav nav a { color: var(--muted); }
.nav nav a:hover { color: var(--ink); text-decoration: none; }
.lang { display: flex; background: var(--card); border-radius: 980px; padding: 3px; }
.lang button { appearance: none; border: 0; background: transparent; color: var(--muted); font: 500 12px var(--sans); padding: 5px 12px; border-radius: 980px; cursor: pointer; }
.lang button[aria-pressed="true"] { background: var(--surface); color: var(--ink); box-shadow: 0 1px 3px rgba(0,0,0,.12); }

/* Layout */
.page { width: min(1120px, calc(100% - 48px)); margin: 0 auto; padding: 40px 0 72px; }
section + section, .duo, .duo + section { margin-top: 88px; }
h2 { font-family: var(--serif); font-size: 34px; font-weight: 600; color: var(--ink); letter-spacing: -.015em; line-height: 1.2; margin-bottom: 28px; }

/* Buttons */
.actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 22px; }
.btn { display: inline-flex; align-items: center; gap: 4px; font-size: 14px; line-height: 1; padding: 10px 18px; border-radius: 980px; border: 1px solid var(--blue); color: var(--blue); background: transparent; transition: background .2s, color .2s; }
.btn:hover { text-decoration: none; background: rgba(0,113,227,.06); }
.btn.primary { background: var(--blue); color: #fff; }
.btn.primary:hover { background: #0077ed; }
.btn.quiet { border-color: var(--line); color: var(--muted); cursor: default; }
.btn.quiet:hover { background: transparent; }

/* Hero */
.hero-main { display: grid; grid-template-columns: minmax(0, 1fr) 220px; gap: 56px; align-items: start; }
.nameplate { display: block; width: min(100%, 520px); height: auto; margin: 0 0 26px -6px; image-rendering: pixelated; }
.hero-text > p.en, .hero-text > p.zh { font-size: 17px; color: var(--text); max-width: 680px; }
.keywords { margin-top: 18px; font-size: 13px; color: var(--muted); letter-spacing: .02em; }
.portrait { width: 220px; height: auto; aspect-ratio: 4 / 5; object-fit: cover; border-radius: var(--radius); }
.gallery { margin-top: 48px; display: grid; grid-template-columns: 1.35fr 1fr 1fr 1fr; gap: 12px; }
.tile { position: relative; display: block; border-radius: 14px; overflow: hidden; background: var(--card); aspect-ratio: 4 / 3; }
.tile:first-child { aspect-ratio: auto; }
.tile img { display: block; width: 100%; height: 100%; object-fit: cover; transition: transform .5s ease; }
.tile:hover img { transform: scale(1.03); }
.tile-cap { position: absolute; left: 10px; bottom: 10px; font-size: 11px; font-weight: 500; color: var(--ink); background: rgba(255,255,255,.88); backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px); padding: 4px 10px; border-radius: 980px; }
.tile:hover { text-decoration: none; }

/* Paper */
.feature-v2 { background: var(--surface); border: 1px solid var(--hair); border-radius: 24px; padding: 36px; display: grid; gap: 28px; }
.eyebrow { font-size: 12px; font-weight: 600; letter-spacing: .04em; color: #bf4800; margin-bottom: 10px; }
.paper-title { font-family: var(--serif); font-size: 28px; font-weight: 600; color: var(--ink); line-height: 1.25; letter-spacing: -.01em; }
.paper-tagline { font-size: 17px; color: var(--muted); margin-top: 8px; }
.authors { margin-top: 14px; font-size: 15px; color: var(--text); }
.authors strong { font-weight: 600; }
.affil { color: var(--muted); }
.feature-points { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 14px; }
.point { background: var(--card); border-radius: 16px; padding: 20px 22px; }
.point-label { font-size: 12px; font-weight: 600; letter-spacing: .04em; color: var(--blue); margin-bottom: 8px; }
.point p:not(.point-label) { font-size: 14.5px; line-height: 1.7; }
.feature-demos { grid-template-columns: 1fr 1fr; }
.feature-demos .film iframe, .feature-demos .film video { aspect-ratio: 16 / 9; }

/* Demo cards (shared) */
.demo-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.demo-card { background: var(--surface); border: 1px solid var(--hair); border-radius: 16px; overflow: hidden; min-width: 0; scroll-margin-top: 80px; }
.card-top { display: flex; justify-content: space-between; gap: 10px; padding: 10px 14px; font-size: 11px; font-weight: 600; letter-spacing: .04em; color: var(--muted); }
.film { background: #000; }
.film video, .film iframe { display: block; width: 100%; height: auto; aspect-ratio: 2.05; object-fit: contain; border: 0; }
.card-copy { padding: 14px 16px 16px; }
h4 { font-family: var(--serif); font-size: 17px; font-weight: 600; color: var(--ink); line-height: 1.4; margin-bottom: 6px; }
.card-copy p { font-size: 13.5px; line-height: 1.65; color: var(--muted); }

/* News and education */
.duo { display: grid; grid-template-columns: minmax(0, 1.6fr) minmax(0, 1fr); gap: 20px; align-items: stretch; }
.duo > section { margin-top: 0; background: var(--card); border-radius: 24px; padding: 32px; }
.duo h2 { font-size: 26px; margin-bottom: 18px; }
.news { display: grid; gap: 14px; }
.news li { display: grid; grid-template-columns: 128px 1fr; gap: 14px; font-size: 15px; }
.news .when { font-family: var(--mono); font-size: 12.5px; color: var(--muted); padding-top: 3px; }
.org-logos { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; margin-bottom: 14px; }
.org-chip img { display: block; height: 34px; width: auto; }
.org-chip.square img { height: 44px; }
.edu-line { font-size: 15px; }
.edu-line .when { display: block; font-family: var(--mono); font-size: 12.5px; color: var(--muted); margin-bottom: 4px; }

/* Internships */
.internship { background: var(--surface); border: 1px solid var(--hair); border-radius: 24px; padding: 32px; }
.internship + .internship { margin-top: 20px; }
.split { display: grid; grid-template-columns: minmax(0, .85fr) minmax(0, 1.5fr); gap: 32px; align-items: start; }
.entry-title { font-family: var(--serif); font-size: 22px; font-weight: 600; color: var(--ink); line-height: 1.35; margin-bottom: 6px; }
.split-text p { font-size: 15px; margin-bottom: 12px; }
.split-text > p:nth-of-type(1), .split-text > p:nth-of-type(2) { color: var(--muted); }
.utars { display: flex; align-items: center; gap: 12px; margin-top: 16px; font-size: 12px; color: var(--muted); }
.utars img { width: 60px; height: auto; }
.demo-group + .demo-group { margin-top: 18px; }
.demo-group h3 { font-size: 13px; font-weight: 600; color: var(--ink); margin-bottom: 10px; }
.tsinghua-demos { grid-template-columns: 1fr; }
.tsinghua-demos .film video { aspect-ratio: 16 / 9; }

.foot { text-align: center; font-size: 12px; color: var(--muted); padding: 28px 0 40px; border-top: 1px solid var(--hair); }

@media (max-width: 900px) {
  .hero-main { grid-template-columns: 1fr 150px; gap: 28px; }
  .portrait { width: 150px; }
  .gallery { grid-template-columns: 1fr 1fr; }
  .tile:first-child { grid-column: 1 / -1; aspect-ratio: 16 / 9; }
  .feature-points, .feature-demos, .duo, .split { grid-template-columns: 1fr; }
  .feature-v2, .internship { padding: 24px; }
}
@media (max-width: 600px) {
  .nav-inner, .page { width: calc(100% - 32px); }
  .nav nav { display: none; }
  .lang { margin-left: auto; }
  .page { padding-top: 24px; }
  .hero-main { grid-template-columns: 1fr; }
  .portrait { width: 120px; order: -1; border-radius: 14px; }
  h2 { font-size: 28px; }
  section + section, .duo, .duo + section { margin-top: 56px; }
  .paper-title { font-size: 22px; }
  .feature-v2, .internship, .duo > section { padding: 20px; border-radius: 20px; }
  .news li { grid-template-columns: 1fr; gap: 2px; }
  .demo-grid { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } .tile img { transition: none; } }

/* Fixes after first preview */
.gallery { grid-auto-rows: 210px; }
.tile, .tile:first-child { aspect-ratio: auto; height: 100%; }
.utars { display: none; }
.org-chip.zgca img { height: 26px; }
#tsinghua { grid-template-columns: 1fr; }
#tsinghua .split-text { max-width: 760px; }
#tsinghua .tsinghua-demos { grid-template-columns: 1fr 1fr; }
@media (max-width: 900px) {
  .gallery { grid-auto-rows: 170px; }
  .tile:first-child { aspect-ratio: auto; grid-row: span 1; }
}
@media (max-width: 600px) {
  .gallery { grid-auto-rows: 120px; gap: 8px; }
  .tile:first-child { grid-row: span 2; grid-column: 1 / -1; }
  #tsinghua .tsinghua-demos { grid-template-columns: 1fr; }
}
@media (max-width: 600px) {
  .gallery { grid-template-columns: repeat(3, 1fr); grid-auto-rows: 96px; }
  .tile:first-child { grid-row: span 2; grid-column: 1 / -1; }
  .tile-cap { font-size: 10px; left: 6px; bottom: 6px; padding: 3px 7px; }
}