:root {
  --ink: #111827;
  --ink-soft: #3d485b;
  --muted: #667085;
  --paper: #ffffff;
  --cloud: #f5f7fb;
  --line: #dce2eb;
  --line-strong: #bdc7d6;
  --pku: #8c1d40;
  --pku-deep: #6e1531;
  --blue: #2656d8;
  --blue-deep: #173a99;
  --cyan: #57c6d4;
  --orange: #f28e4b;
  --green: #1e8e67;
  --max: 1180px;
  --shadow: 0 24px 70px rgba(24, 39, 75, 0.1);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 1rem;
  line-height: 1.65;
  text-rendering: optimizeLegibility;
}

body::before {
  position: fixed;
  inset: 0;
  z-index: -2;
  content: "";
  pointer-events: none;
  background-image:
    linear-gradient(rgba(38, 86, 216, 0.038) 1px, transparent 1px),
    linear-gradient(90deg, rgba(38, 86, 216, 0.038) 1px, transparent 1px);
  background-size: 42px 42px;
  mask-image: linear-gradient(to bottom, black 0, transparent 78vh);
}

a {
  color: inherit;
  text-decoration-color: rgba(38, 86, 216, 0.38);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.22em;
}

a:hover {
  color: var(--blue);
  text-decoration-color: currentColor;
}

img {
  display: block;
  max-width: 100%;
}

button,
input {
  font: inherit;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1,
h2,
h3 {
  line-height: 1.08;
  letter-spacing: -0.035em;
}

h1 {
  font-size: clamp(3.2rem, 8vw, 7.2rem);
}

h2 {
  font-size: clamp(2rem, 4vw, 3.5rem);
}

h3 {
  font-size: clamp(1.2rem, 2vw, 1.55rem);
}

.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;
}

.skip-link {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 100;
  padding: 0.65rem 1rem;
  color: #fff;
  background: var(--ink);
  border-radius: 0.35rem;
  transform: translateY(-160%);
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, 0.91);
  border-bottom: 1px solid rgba(189, 199, 214, 0.7);
  backdrop-filter: blur(18px);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: min(calc(100% - 2.4rem), var(--max));
  min-height: 78px;
  margin: 0 auto;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.8rem;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 42px;
  height: 42px;
  color: #fff;
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  background: var(--pku);
  place-items: center;
}

.brand-copy {
  display: grid;
  line-height: 1.1;
}

.brand-copy strong {
  font-size: 1rem;
  letter-spacing: -0.02em;
}

.brand-copy small {
  margin-top: 0.3rem;
  color: var(--muted);
  font-size: 0.7rem;
  font-weight: 650;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 0.2rem;
}

.site-nav a {
  padding: 0.55rem 0.72rem;
  color: var(--ink-soft);
  font-size: 0.9rem;
  font-weight: 650;
  text-decoration: none;
  border-radius: 0.3rem;
}

.site-nav a:hover,
.site-nav a[aria-current="page"] {
  color: var(--pku);
  background: rgba(140, 29, 64, 0.07);
}

.site-nav .nav-contact {
  margin-left: 0.5rem;
  color: #fff;
  background: var(--ink);
}

.site-nav .nav-contact:hover {
  color: #fff;
  background: var(--blue);
}

.nav-toggle {
  display: none;
  width: 42px;
  height: 42px;
  padding: 9px;
  background: transparent;
  border: 1px solid var(--line);
  border-radius: 0.25rem;
}

.nav-toggle > span:not(.sr-only) {
  display: block;
  height: 2px;
  margin: 4px 0;
  background: var(--ink);
}

.shell {
  width: min(calc(100% - 2.4rem), var(--max));
  margin: 0 auto;
}

.section {
  padding: clamp(4.5rem, 9vw, 8rem) 0;
}

.section-soft {
  position: relative;
  background: var(--cloud);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.section-head {
  display: grid;
  grid-template-columns: minmax(0, 0.78fr) minmax(280px, 0.42fr);
  gap: 4rem;
  align-items: end;
  margin-bottom: 3.2rem;
}

.section-head h2,
.page-intro h1 {
  margin-bottom: 0;
}

.section-head p,
.page-intro .lede {
  max-width: 58ch;
  margin-bottom: 0;
  color: var(--ink-soft);
  font-size: 1.08rem;
}

.eyebrow {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  margin-bottom: 1.15rem;
  color: var(--pku);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.eyebrow::before {
  width: 28px;
  height: 2px;
  content: "";
  background: currentColor;
}

.text-link {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  color: var(--blue);
  font-weight: 750;
  text-decoration: none;
}

.text-link::after {
  content: "↗";
  transition: transform 150ms ease;
}

.text-link:hover::after {
  transform: translate(2px, -2px);
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0.7rem 1.1rem;
  color: #fff;
  font-weight: 750;
  text-decoration: none;
  background: var(--ink);
  border: 1px solid var(--ink);
  border-radius: 0.32rem;
}

.button:hover {
  color: #fff;
  background: var(--blue);
  border-color: var(--blue);
}

.button-outline {
  color: var(--ink);
  background: #fff;
  border-color: var(--line-strong);
}

.button-outline:hover {
  color: var(--pku);
  background: rgba(140, 29, 64, 0.04);
  border-color: var(--pku);
}

.hero {
  position: relative;
  overflow: hidden;
  border-bottom: 1px solid var(--line);
}

.hero::after {
  position: absolute;
  top: 10%;
  right: -10%;
  z-index: -1;
  width: 42vw;
  height: 42vw;
  content: "";
  background: radial-gradient(circle, rgba(38, 86, 216, 0.14), transparent 67%);
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.12fr) minmax(340px, 0.68fr);
  gap: clamp(3rem, 7vw, 7rem);
  align-items: center;
  min-height: calc(100vh - 78px);
  padding: clamp(4rem, 8vh, 7rem) 0;
}

.hero h1 {
  margin: 0 0 0.5rem;
  font-size: clamp(3rem, 5.5vw, 5.25rem);
  white-space: nowrap;
}

.hero h1 span {
  display: inline;
  color: transparent;
  -webkit-text-stroke: 1.5px var(--blue);
}

.hero-role {
  max-width: 760px;
  margin: 1.4rem 0 1.35rem;
  color: var(--ink-soft);
  font-size: clamp(1.15rem, 2.2vw, 1.55rem);
  line-height: 1.52;
}

.hero-role a {
  color: var(--pku);
  font-weight: 750;
}

.hero-focus {
  max-width: 700px;
  margin-bottom: 2rem;
  color: var(--muted);
}

.hero-visual {
  position: relative;
  width: min(100%, 360px);
  justify-self: end;
}

.portrait-frame {
  position: relative;
  aspect-ratio: 1 / 1;
  padding: 1.1rem;
  background: #fff;
  border: 1px solid var(--line-strong);
  box-shadow: var(--shadow);
}

.portrait-frame::before,
.portrait-frame::after {
  position: absolute;
  z-index: -1;
  width: 56%;
  height: 56%;
  content: "";
  border: 2px solid var(--blue);
}

.portrait-frame::before {
  top: -14px;
  right: -14px;
  border-bottom: 0;
  border-left: 0;
}

.portrait-frame::after {
  bottom: -14px;
  left: -14px;
  border-top: 0;
  border-right: 0;
  border-color: var(--pku);
}

.portrait-frame img {
  display: block;
  width: 100%;
  height: 100%;
  aspect-ratio: 1 / 1;
  object-fit: cover;
}

.coordinate-card {
  position: absolute;
  right: -2rem;
  bottom: -2.4rem;
  width: min(280px, 78%);
  padding: 1rem 1.15rem;
  color: #fff;
  background: var(--ink);
  box-shadow: 0 18px 40px rgba(17, 24, 39, 0.22);
}

.coordinate-card small {
  display: block;
  margin-bottom: 0.25rem;
  color: #aab6ca;
  font-size: 0.68rem;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.coordinate-card strong {
  font-size: 0.95rem;
}

.signal-strip {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  background: var(--ink);
}

.signal {
  min-height: 148px;
  padding: 1.8rem;
  color: #fff;
  border-right: 1px solid rgba(255, 255, 255, 0.15);
}

.signal:last-child {
  border-right: 0;
}

.signal small {
  display: block;
  margin-bottom: 0.75rem;
  color: #9eacc1;
  font-size: 0.7rem;
  font-weight: 800;
  letter-spacing: 0.13em;
  text-transform: uppercase;
}

.signal strong {
  display: block;
  font-size: 1.05rem;
  line-height: 1.35;
}

.signal span {
  display: block;
  margin-top: 0.35rem;
  color: #9eacc1;
  font-size: 0.78rem;
  line-height: 1.4;
}

.recruit-band {
  display: grid;
  grid-template-columns: 0.75fr 1.25fr auto;
  gap: 2rem;
  align-items: center;
  padding: 2.1rem;
  background: #fff;
  border: 1px solid var(--line-strong);
  border-top: 5px solid var(--pku);
  box-shadow: var(--shadow);
}

.recruit-band h2 {
  margin-bottom: 0;
  font-size: clamp(1.55rem, 3vw, 2.4rem);
}

.recruit-band p {
  margin-bottom: 0;
  color: var(--ink-soft);
  font-weight: 650;
}

.research-grid,
.project-grid,
.talk-grid,
.course-grid,
.fact-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  overflow: hidden;
  background: var(--line);
  border: 1px solid var(--line);
}

.research-card,
.project-card,
.talk-card,
.course-card,
.fact-card {
  position: relative;
  padding: clamp(1.6rem, 3.5vw, 2.6rem);
  background: #fff;
}

.research-card {
  min-height: 330px;
}

.research-card .card-index,
.project-card .card-index {
  display: inline-grid;
  width: 34px;
  height: 34px;
  margin-bottom: 3.5rem;
  color: var(--blue);
  font-size: 0.76rem;
  font-weight: 850;
  border: 1px solid currentColor;
  border-radius: 50%;
  place-items: center;
}

.research-card:nth-child(2) .card-index {
  color: var(--pku);
}

.research-card:nth-child(3) .card-index {
  color: var(--green);
}

.research-card:nth-child(4) .card-index {
  color: var(--orange);
}

.research-card p,
.project-card p,
.talk-card p,
.course-card p,
.fact-card p {
  margin-bottom: 0;
  color: var(--ink-soft);
}

.research-card a,
.project-card a {
  position: absolute;
  right: 2rem;
  bottom: 1.6rem;
  color: var(--blue);
  font-weight: 800;
  text-decoration: none;
}

.project-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.project-card {
  min-height: 310px;
}

.project-card .card-index {
  margin-bottom: 2.6rem;
  color: var(--pku);
}

.project-card h3 {
  margin-bottom: 1rem;
}

.project-meta,
.paper-meta,
.talk-meta,
.course-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem 0.8rem;
  margin-bottom: 1rem;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 750;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.page-intro {
  padding: clamp(5.5rem, 10vw, 9.5rem) 0 clamp(3.8rem, 7vw, 6rem);
  border-bottom: 1px solid var(--line);
}

.page-intro-grid {
  display: grid;
  grid-template-columns: minmax(0, 0.8fr) minmax(280px, 0.42fr);
  gap: 4rem;
  align-items: end;
}

.page-intro h1 {
  font-size: clamp(3.2rem, 8vw, 6.8rem);
}

.page-number {
  display: block;
  margin-bottom: 1.25rem;
  color: var(--blue);
  font-size: 0.72rem;
  font-weight: 850;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.prose-grid {
  display: grid;
  grid-template-columns: minmax(220px, 0.36fr) minmax(0, 0.84fr);
  gap: clamp(3rem, 7vw, 7rem);
}

.prose-sticky {
  position: sticky;
  top: 120px;
  align-self: start;
}

.prose-sticky h2 {
  font-size: clamp(1.8rem, 3vw, 2.8rem);
}

.prose-main > :last-child {
  margin-bottom: 0;
}

.principle {
  padding: 2rem 0;
  border-top: 1px solid var(--line);
}

.principle:first-child {
  padding-top: 0;
  border-top: 0;
}

.principle h3 {
  margin-bottom: 0.8rem;
}

.principle p {
  color: var(--ink-soft);
}

.principle-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem 1rem;
  margin-top: 1rem;
}

.principle-links a {
  color: var(--blue);
  font-size: 0.86rem;
  font-weight: 750;
}

.course-archive-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px;
  overflow: hidden;
  background: var(--line);
  border: 1px solid var(--line);
}

.course-archive-link {
  display: flex;
  min-height: 190px;
  padding: 1.6rem;
  color: var(--ink);
  text-decoration: none;
  background: #fff;
  flex-direction: column;
  transition: color 180ms ease, background 180ms ease;
}

.course-archive-link:hover {
  color: var(--blue);
  background: var(--paper);
}

.course-archive-link span {
  margin-bottom: 1.25rem;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.course-archive-link strong {
  font-family: inherit;
  font-size: 1.2rem;
  line-height: 1.25;
}

.course-archive-link small {
  margin-top: auto;
  padding-top: 1.5rem;
  color: var(--blue);
  font-size: 0.78rem;
  font-weight: 800;
}

.section-action {
  margin-top: 2rem;
}

.course-hero {
  position: relative;
  overflow: hidden;
  padding: clamp(3.5rem, 7vw, 6.5rem) 0 clamp(4.5rem, 8vw, 7rem);
  color: #fff;
  background:
    linear-gradient(rgba(87, 198, 212, 0.07) 1px, transparent 1px),
    linear-gradient(90deg, rgba(87, 198, 212, 0.07) 1px, transparent 1px),
    #0b101b;
  background-size: 42px 42px;
  border-bottom: 5px solid var(--pku);
}

.course-hero::after {
  position: absolute;
  right: -12rem;
  bottom: -18rem;
  width: 42rem;
  height: 42rem;
  content: "";
  pointer-events: none;
  background: radial-gradient(circle, rgba(38, 86, 216, 0.46), transparent 66%);
}

.course-back {
  position: relative;
  z-index: 1;
  display: inline-flex;
  margin-bottom: clamp(3.5rem, 7vw, 6rem);
  color: #aebbd0;
  font-size: 0.82rem;
  font-weight: 750;
  letter-spacing: 0.04em;
  text-decoration: none;
}

.course-back:hover {
  color: #fff;
}

.course-hero-grid {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(300px, 0.42fr);
  gap: clamp(3rem, 7vw, 7rem);
  align-items: end;
}

.course-kicker {
  display: block;
  margin-bottom: 1.25rem;
  color: #77d7e2;
  font-size: 0.78rem;
  font-weight: 850;
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

.course-hero h1 {
  max-width: 900px;
  margin-bottom: 1.2rem;
  font-size: clamp(3rem, 6vw, 5.4rem);
  overflow-wrap: anywhere;
}

.course-code {
  margin-bottom: 0;
  color: #cbd5e5;
  font-size: clamp(1.05rem, 2vw, 1.35rem);
  font-weight: 700;
  letter-spacing: 0.03em;
}

.course-facts {
  margin: 0;
  background: rgba(255, 255, 255, 0.07);
  border: 1px solid rgba(255, 255, 255, 0.16);
  backdrop-filter: blur(14px);
}

.course-facts div {
  display: grid;
  grid-template-columns: 92px minmax(0, 1fr);
  gap: 1rem;
  padding: 1rem 1.15rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.11);
}

.course-facts div:last-child {
  border-bottom: 0;
}

.course-facts dt {
  color: #8fa0b9;
  font-size: 0.7rem;
  font-weight: 850;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.course-facts dd {
  margin: 0;
  color: #f3f6fb;
  font-size: 0.92rem;
  font-weight: 700;
}

.course-section {
  padding: clamp(4rem, 8vw, 7rem) 0;
}

.course-page-grid {
  display: grid;
  grid-template-columns: 220px minmax(0, 820px);
  gap: clamp(3rem, 7vw, 7rem);
  justify-content: center;
  align-items: start;
}

.course-sidebar {
  position: sticky;
  top: 108px;
}

.course-sidebar-card {
  padding: 1.35rem;
  background: var(--cloud);
  border-top: 3px solid var(--blue);
}

.course-sidebar-label {
  display: block;
  margin-bottom: 0.9rem;
  color: var(--muted);
  font-size: 0.7rem;
  font-weight: 850;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.course-toc {
  display: grid;
  gap: 0.18rem;
}

.course-toc a {
  padding: 0.38rem 0;
  color: var(--ink-soft);
  font-size: 0.86rem;
  font-weight: 650;
  line-height: 1.35;
  text-decoration: none;
}

.course-toc a:hover {
  color: var(--blue);
}

.course-all-link {
  display: inline-flex;
  margin-top: 1.2rem;
  padding-top: 1rem;
  color: var(--pku);
  font-size: 0.82rem;
  font-weight: 800;
  text-decoration: none;
  border-top: 1px solid var(--line);
}

.course-content {
  min-width: 0;
  color: var(--ink-soft);
  font-size: 1.05rem;
  line-height: 1.78;
}

.course-content > p:first-child {
  color: var(--ink);
  font-size: 1.22rem;
  line-height: 1.65;
}

.course-content h1,
.course-content h2 {
  margin: 4.5rem 0 1.35rem;
  padding-top: 1.6rem;
  color: var(--ink);
  font-size: clamp(1.9rem, 4vw, 2.8rem);
  border-top: 1px solid var(--line-strong);
  scroll-margin-top: 110px;
}

.course-content h1:first-child,
.course-content h2:first-child {
  margin-top: 0;
}

.course-content h3 {
  margin: 3rem 0 1rem;
  color: var(--ink);
  font-size: clamp(1.28rem, 2.5vw, 1.65rem);
  line-height: 1.28;
}

.course-content h4 {
  margin: 2rem 0 0.75rem;
  color: var(--pku);
  font-size: 1rem;
  line-height: 1.4;
  letter-spacing: 0.01em;
}

.course-content p,
.course-content ul,
.course-content ol {
  max-width: 75ch;
}

.course-content ul,
.course-content ol {
  padding-left: 1.35rem;
}

.course-content li + li {
  margin-top: 0.42rem;
}

.course-content li::marker {
  color: var(--blue);
}

.course-content a {
  color: var(--blue-deep);
  font-weight: 650;
  overflow-wrap: anywhere;
}

.course-content a:hover {
  color: var(--pku);
}

.course-content strong {
  color: var(--ink);
}

.course-content hr {
  margin: 3rem 0;
  border: 0;
  border-top: 1px solid var(--line);
}

.course-content blockquote {
  margin: 2rem 0;
  padding: 1.2rem 1.4rem;
  color: var(--ink-soft);
  background: var(--cloud);
  border-left: 3px solid var(--pku);
}

.course-content table {
  width: 100%;
  margin: 2rem 0;
  border-collapse: collapse;
}

.course-content th,
.course-content td {
  padding: 0.75rem;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--line);
}

.course-content font[color="red"] {
  color: var(--pku);
  font-weight: 750;
}

.arc {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  border-top: 1px solid var(--line-strong);
  border-bottom: 1px solid var(--line-strong);
}

.arc-step {
  position: relative;
  min-height: 240px;
  padding: 1.6rem;
  border-right: 1px solid var(--line-strong);
}

.arc-step:last-child {
  border-right: 0;
}

.arc-step::before {
  display: block;
  width: 12px;
  height: 12px;
  margin-bottom: 3rem;
  content: "";
  background: var(--blue);
  border-radius: 50%;
}

.arc-step:nth-child(2)::before { background: var(--cyan); }
.arc-step:nth-child(3)::before { background: var(--orange); }
.arc-step:nth-child(4)::before { background: var(--pku); }

.arc-step small {
  display: block;
  margin-bottom: 0.8rem;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 850;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.arc-step strong {
  display: block;
  margin-bottom: 0.75rem;
  font-size: 1.15rem;
  line-height: 1.3;
}

.arc-step p {
  color: var(--ink-soft);
  font-size: 0.92rem;
}

.publication-tools {
  display: grid;
  grid-template-columns: minmax(240px, 0.75fr) minmax(0, 1.25fr);
  gap: 1rem;
  align-items: center;
  margin-bottom: 2rem;
}

.publication-search {
  width: 100%;
  min-height: 48px;
  padding: 0.7rem 0.9rem;
  color: var(--ink);
  background: #fff;
  border: 1px solid var(--line-strong);
  border-radius: 0.25rem;
}

.publication-search:focus {
  border-color: var(--blue);
  outline: 3px solid rgba(38, 86, 216, 0.13);
}

.filter-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  justify-content: flex-end;
}

.filter-button {
  min-height: 40px;
  padding: 0.45rem 0.72rem;
  color: var(--ink-soft);
  font-size: 0.82rem;
  font-weight: 750;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 999px;
  cursor: pointer;
}

.filter-button:hover,
.filter-button[aria-pressed="true"] {
  color: #fff;
  background: var(--ink);
  border-color: var(--ink);
}

.paper-list {
  border-top: 1px solid var(--line-strong);
}

.paper {
  display: grid;
  grid-template-columns: 120px minmax(0, 1fr) auto;
  gap: 1.5rem;
  align-items: start;
  padding: 1.7rem 0;
  border-bottom: 1px solid var(--line);
}

.paper[hidden] {
  display: none;
}

.paper-year {
  color: var(--pku);
  font-size: 0.78rem;
  font-weight: 850;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.paper h3 {
  margin-bottom: 0.55rem;
  font-size: 1.16rem;
  letter-spacing: -0.02em;
  line-height: 1.35;
}

.paper h3 a {
  text-decoration: none;
}

.paper-authors {
  margin-bottom: 0.45rem;
  color: var(--ink-soft);
  font-size: 0.93rem;
}

.paper-note {
  margin-bottom: 0;
  color: var(--muted);
  font-size: 0.86rem;
}

.paper-tag {
  padding: 0.3rem 0.55rem;
  color: var(--blue);
  font-size: 0.68rem;
  font-weight: 850;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  border: 1px solid rgba(38, 86, 216, 0.35);
  border-radius: 999px;
  white-space: nowrap;
}

.paper-empty {
  padding: 2.5rem;
  color: var(--muted);
  text-align: center;
  border: 1px solid var(--line);
}

.talk-grid,
.course-grid,
.fact-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.talk-card,
.course-card,
.fact-card {
  min-height: 265px;
}

.talk-card h3,
.course-card h3 {
  margin-bottom: 0.8rem;
  line-height: 1.3;
}

.talk-card .text-link,
.course-card .text-link {
  margin-top: 1.25rem;
}

.timeline {
  border-top: 1px solid var(--line-strong);
}

.timeline-item {
  display: grid;
  grid-template-columns: 170px minmax(0, 1fr);
  gap: 2rem;
  padding: 1.8rem 0;
  border-bottom: 1px solid var(--line);
}

.timeline-date {
  color: var(--pku);
  font-size: 0.78rem;
  font-weight: 850;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.timeline-item h3 {
  margin-bottom: 0.5rem;
  font-size: 1.18rem;
  line-height: 1.35;
}

.timeline-item p {
  margin-bottom: 0;
  color: var(--ink-soft);
}

.student-profile {
  display: grid;
  grid-template-columns: minmax(280px, 0.62fr) minmax(0, 1.38fr);
  overflow: hidden;
  background: #fff;
  border: 1px solid var(--line-strong);
  box-shadow: var(--shadow);
}

.student-profile-summary {
  padding: clamp(2rem, 4vw, 3.5rem);
  color: #fff;
  background: var(--ink);
}

.student-status {
  display: inline-block;
  margin-bottom: 3rem;
  padding: 0.35rem 0.6rem;
  color: #b8c9ff;
  font-size: 0.7rem;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  border: 1px solid rgba(184, 201, 255, 0.45);
  border-radius: 999px;
}

.student-profile-summary h3 {
  margin-bottom: 0.55rem;
  font-size: clamp(2rem, 4vw, 3.4rem);
}

.student-affiliation {
  margin-bottom: 2rem;
  color: #c5cede;
  font-weight: 650;
}

.student-topic-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.student-topic-list span {
  padding: 0.38rem 0.62rem;
  color: #dbe3f1;
  font-size: 0.78rem;
  border: 1px solid rgba(255, 255, 255, 0.18);
  border-radius: 999px;
}

.student-paper-list {
  display: flex;
  flex-direction: column;
}

.student-paper-row {
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr) 28px;
  gap: 1.4rem;
  align-items: center;
  min-height: 118px;
  padding: 1.35rem clamp(1.4rem, 3vw, 2.2rem);
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid var(--line);
  transition: color 160ms ease, background 160ms ease;
}

.student-paper-row:last-child {
  border-bottom: 0;
}

.student-paper-row:hover {
  color: var(--blue-deep);
  background: var(--cloud);
}

.student-paper-index {
  display: grid;
  width: 36px;
  height: 36px;
  color: var(--blue);
  font-size: 0.7rem;
  font-weight: 850;
  letter-spacing: 0.05em;
  border: 1px solid currentColor;
  border-radius: 50%;
  place-items: center;
}

.student-paper-meta {
  color: var(--pku);
  font-size: 0.7rem;
  font-weight: 850;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.student-paper-content {
  display: grid;
  gap: 0.3rem;
}

.student-paper-content strong {
  font-size: 1rem;
  line-height: 1.35;
  letter-spacing: -0.015em;
}

.student-paper-content small {
  color: var(--muted);
  font-size: 0.8rem;
  line-height: 1.45;
}

.student-paper-arrow {
  color: var(--blue);
  font-size: 1.1rem;
  transition: transform 160ms ease;
}

.student-paper-row:hover .student-paper-arrow {
  transform: translate(2px, -2px);
}

.student-timeline .timeline-item {
  grid-template-columns: 180px minmax(0, 1fr);
}

.student-placement {
  font-weight: 700;
}

.student-placement span {
  margin-right: 0.55rem;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 850;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.student-result {
  margin-top: 0.35rem !important;
  color: var(--blue-deep) !important;
  font-size: 0.9rem;
}

.committee-grid .fact-card {
  min-height: 220px;
}

.student-name-list {
  padding: 0;
  margin: 2.2rem 0 0;
  list-style: none;
}

.student-name-list li {
  padding: 0.55rem 0;
  font-size: 1.08rem;
  font-weight: 750;
  border-top: 1px solid var(--line);
}

.join-panel {
  display: grid;
  grid-template-columns: minmax(0, 0.75fr) minmax(300px, 0.55fr);
  gap: 4rem;
  align-items: center;
  padding: clamp(2rem, 5vw, 4.2rem);
  color: #fff;
  background: var(--ink);
}

.join-panel h2 {
  margin-bottom: 1rem;
}

.join-panel p {
  margin-bottom: 0;
  color: #c5cede;
}

.join-panel .button {
  color: var(--ink);
  background: #fff;
  border-color: #fff;
}

.join-panel .button:hover {
  color: #fff;
  background: var(--pku);
  border-color: var(--pku);
}

.site-footer {
  padding: 4rem max(1.2rem, calc((100% - var(--max)) / 2));
  color: #d7deea;
  background: #0b101b;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.25fr 1fr 1fr;
  gap: 4rem;
  padding-bottom: 3rem;
}

.footer-grid > div {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
}

.footer-name {
  color: #fff;
  font-size: 1.4rem;
  font-weight: 850;
  letter-spacing: -0.03em;
  text-decoration: none;
}

.footer-grid p {
  max-width: 42ch;
  margin: 0.8rem 0 0;
  color: #9eacc1;
}

.footer-grid a,
.footer-grid span {
  margin-bottom: 0.42rem;
  color: #c5cede;
  text-decoration: none;
}

.footer-grid a:hover {
  color: #fff;
}

.footer-label {
  color: #7e8ca2 !important;
  font-size: 0.7rem;
  font-weight: 850;
  letter-spacing: 0.13em;
  text-transform: uppercase;
}

.footer-bottom {
  display: flex;
  justify-content: space-between;
  padding-top: 1.4rem;
  color: #7e8ca2;
  font-size: 0.78rem;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

@media (max-width: 980px) {
  .nav-toggle {
    display: block;
  }

  .site-nav {
    position: absolute;
    top: 78px;
    right: 0;
    left: 0;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 0.7rem 1.2rem 1.2rem;
    background: #fff;
    border-bottom: 1px solid var(--line);
    box-shadow: 0 20px 30px rgba(17, 24, 39, 0.08);
  }

  .site-nav.is-open {
    display: flex;
  }

  .site-nav a {
    padding: 0.8rem;
  }

  .site-nav .nav-contact {
    margin: 0.4rem 0 0;
    text-align: center;
  }

  .hero-grid {
    grid-template-columns: 1fr;
    min-height: 0;
    padding: 5rem 0 6.5rem;
  }

  .hero-copy {
    max-width: 800px;
  }

  .hero-visual {
    width: min(72%, 360px);
    justify-self: center;
    margin: 0 auto;
  }

  .signal-strip {
    grid-template-columns: repeat(2, 1fr);
  }

  .signal:nth-child(2) {
    border-right: 0;
  }

  .signal:nth-child(-n + 2) {
    border-bottom: 1px solid rgba(255, 255, 255, 0.15);
  }

  .recruit-band,
  .join-panel,
  .student-profile {
    grid-template-columns: 1fr;
  }

  .research-grid,
  .project-grid,
  .talk-grid,
  .course-grid,
  .fact-grid,
  .course-archive-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-intro-grid,
  .section-head,
  .course-hero-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }

  .course-page-grid {
    grid-template-columns: 1fr;
    gap: 3rem;
  }

  .course-sidebar {
    position: static;
  }

  .course-toc {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .arc {
    grid-template-columns: repeat(2, 1fr);
  }

  .arc-step:nth-child(2) {
    border-right: 0;
  }

  .arc-step:nth-child(-n + 2) {
    border-bottom: 1px solid var(--line-strong);
  }

  .publication-tools {
    grid-template-columns: 1fr;
  }

  .filter-row {
    justify-content: flex-start;
  }
}

@media (max-width: 700px) {
  body {
    font-size: 1rem;
  }

  .header-inner,
  .shell {
    width: min(calc(100% - 1.5rem), var(--max));
  }

  .brand-copy small {
    display: none;
  }

  .hero h1 {
    font-size: clamp(2.6rem, 13vw, 3.8rem);
  }

  .hero-role {
    font-size: 1.08rem;
  }

  .hero-visual {
    width: min(calc(100% - 3rem), 320px);
  }

  .coordinate-card {
    right: -0.5rem;
    bottom: -2.8rem;
  }

  .signal-strip,
  .research-grid,
  .project-grid,
  .talk-grid,
  .course-grid,
  .fact-grid,
  .course-archive-grid,
  .arc {
    grid-template-columns: 1fr;
  }

  .signal,
  .signal:nth-child(2),
  .research-card,
  .project-card,
  .talk-card,
  .course-card,
  .fact-card,
  .arc-step,
  .arc-step:nth-child(2) {
    border-right: 0;
  }

  .signal,
  .signal:nth-child(-n + 2),
  .arc-step,
  .arc-step:nth-child(-n + 2) {
    border-bottom: 1px solid var(--line-strong);
  }

  .signal:last-child,
  .arc-step:last-child {
    border-bottom: 0;
  }

  .recruit-band {
    padding: 1.5rem;
  }

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

  .prose-sticky {
    position: static;
  }

  .paper {
    grid-template-columns: 70px minmax(0, 1fr);
    gap: 1rem;
  }

  .paper-tag {
    display: none;
  }

  .timeline-item {
    grid-template-columns: 1fr;
    gap: 0.45rem;
  }

  .student-paper-row {
    grid-template-columns: 36px minmax(0, 1fr) 20px;
    gap: 0.65rem 1rem;
    min-height: 0;
    padding: 1.25rem;
  }

  .student-paper-index {
    width: 32px;
    height: 32px;
  }

  .student-timeline .timeline-item {
    grid-template-columns: 1fr;
  }

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

  .footer-bottom {
    flex-direction: column;
    gap: 0.4rem;
  }

  .course-hero {
    padding: 2.5rem 0 4rem;
  }

  .course-back {
    margin-bottom: 3rem;
  }

  .course-hero h1 {
    font-size: clamp(2.6rem, 13vw, 4.4rem);
  }

  .course-facts div {
    grid-template-columns: 1fr;
    gap: 0.25rem;
  }

  .course-toc {
    grid-template-columns: 1fr;
  }

  .course-content {
    font-size: 1rem;
  }

  .course-content h1,
  .course-content h2 {
    margin-top: 3.5rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}