:root {
  --ink: #16212c; --muted: #5f6972; --paper: #f5f2eb; --white: #fffdf8;
  --pku: #761018; --pku-dark: #4f0710; --blue: #173b55;
  --line: rgba(22, 33, 44, .16); --max: 1180px;
  --serif: "Songti SC", "STSong", "Noto Serif CJK SC", Georgia, serif;
  --sans: Inter, "Helvetica Neue", "PingFang SC", "Microsoft YaHei", sans-serif;
}
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: var(--paper); color: var(--ink); font-family: var(--sans); line-height: 1.7; }
a { color: inherit; text-decoration: none; }
button { font: inherit; }
.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; left: 1rem; top: -4rem; z-index: 99; background: var(--ink); color: white; padding: .7rem 1rem; }
.skip-link:focus { top: 1rem; }

.site-header { position: fixed; inset: 0 0 auto; z-index: 50; border-bottom: 1px solid transparent; transition: .25s ease; }
.site-header.scrolled { background: rgba(245, 242, 235, .94); border-color: var(--line); backdrop-filter: blur(16px); }
.nav-wrap { width: min(calc(100% - 48px), var(--max)); height: 86px; margin: auto; display: flex; align-items: center; justify-content: space-between; }
.brand { display: inline-flex; align-items: center; gap: 13px; }
.brand-mark { display: grid; place-items: center; width: 46px; height: 46px; color: white; background: var(--pku); border-radius: 50%; font-size: .75rem; font-weight: 800; letter-spacing: .08em; }
.brand-copy { display: flex; flex-direction: column; line-height: 1.15; }
.brand-copy strong { font-size: .95rem; letter-spacing: .11em; }
.brand-copy small { color: var(--muted); margin-top: 4px; font-size: .68rem; letter-spacing: .12em; text-transform: uppercase; }
.site-nav { display: flex; align-items: center; gap: 28px; font-size: .88rem; }
.site-nav a { position: relative; }
.site-nav a:not(.nav-cta)::after { content: ""; position: absolute; left: 0; right: 100%; bottom: -6px; height: 1px; background: var(--pku); transition: right .2s; }
.site-nav a:hover::after, .site-nav a:focus-visible::after { right: 0; }
.nav-cta { border: 1px solid var(--ink); border-radius: 100px; padding: 9px 17px; transition: .2s; }
.nav-cta:hover, .nav-cta:focus-visible { color: white; background: var(--ink); }
.nav-toggle { display: none; border: 0; background: transparent; padding: 9px; }
.nav-toggle span:not(.sr-only) { display: block; width: 24px; height: 2px; margin: 5px; background: var(--ink); }

.hero { position: relative; min-height: 680px; padding: 128px 24px 36px; overflow: hidden; }
.hero::before { content: ""; position: absolute; width: 480px; height: 480px; border-radius: 50%; right: -180px; top: -165px; background: rgba(118, 16, 24, .08); }
.hero-grid { position: absolute; inset: 0; opacity: .45; background-image: linear-gradient(var(--line) 1px, transparent 1px), linear-gradient(90deg, var(--line) 1px, transparent 1px); background-size: 72px 72px; mask-image: linear-gradient(to bottom, #000, transparent 85%); }
.hero-inner { position: relative; width: min(100%, var(--max)); min-height: 500px; margin: auto; display: grid; grid-template-columns: 1.22fr .78fr; gap: 62px; align-items: center; }
.eyebrow, .section-no { margin: 0; color: var(--pku); font-size: .76rem; font-weight: 700; letter-spacing: .16em; text-transform: uppercase; }
.hero h1 { max-width: 700px; margin: 22px 0 24px; font-family: var(--serif); font-size: clamp(2.9rem, 5.35vw, 5.25rem); line-height: 1.08; font-weight: 600; letter-spacing: -.04em; }
.hero h1 em { color: var(--pku); font-style: normal; }
.hero-lead { max-width: 620px; color: var(--muted); font-size: 1rem; }
.hero-actions { display: flex; align-items: center; gap: 24px; margin-top: 30px; }
.button { display: inline-flex; align-items: center; justify-content: center; border-radius: 3px; padding: 12px 20px; font-size: .88rem; font-weight: 650; }
.button-primary { color: white; background: var(--pku); box-shadow: 0 10px 30px rgba(118, 16, 24, .18); }
.button-primary:hover, .button-primary:focus-visible { background: var(--pku-dark); transform: translateY(-1px); }
.text-link { border-bottom: 1px solid var(--ink); padding: 6px 0; font-size: .9rem; }
.hero-card { position: relative; min-height: 410px; padding: 26px; display: flex; flex-direction: column; justify-content: space-between; color: white; background: var(--blue); box-shadow: 22px 22px 0 rgba(23, 59, 85, .09); overflow: hidden; }
.hero-card::after { content: ""; position: absolute; inset: auto -100px -140px auto; width: 300px; height: 300px; border: 1px solid rgba(255,255,255,.22); border-radius: 50%; }
.card-index { font-size: .72rem; letter-spacing: .18em; opacity: .72; }
.orb { position: relative; align-self: center; width: 160px; height: 160px; border-radius: 50%; border: 1px solid rgba(255,255,255,.45); }
.orb span { position: absolute; border-radius: 50%; border: 1px solid rgba(255,255,255,.35); }
.orb span:nth-child(1) { inset: 26px; }
.orb span:nth-child(2) { width: 14px; height: 14px; background: white; border: 0; left: 24px; top: 72px; }
.orb span:nth-child(3) { width: 44px; height: 44px; right: 26px; top: 38px; background: var(--pku); border: 0; }
.hero-card-copy { position: relative; z-index: 1; display: flex; flex-direction: column; gap: 8px; }
.hero-card-copy span { opacity: .7; font-size: .72rem; letter-spacing: .1em; text-transform: uppercase; }
.hero-card-copy strong { font-family: var(--serif); font-size: 1.7rem; line-height: 1.22; font-weight: 500; }

.section { padding: 88px 24px; }
.section-heading { width: min(100%, var(--max)); margin: 0 auto 44px; display: grid; grid-template-columns: 1fr 3fr; gap: 30px; }
.section-heading h2 { margin: -8px 0 7px; font-family: var(--serif); font-size: clamp(2.1rem, 3.2vw, 3.35rem); line-height: 1.12; font-weight: 600; letter-spacing: -.03em; }
.intro { background: var(--white); }
.research-grid { width: min(100%, var(--max)); margin: auto; display: grid; grid-template-columns: repeat(3, 1fr); border-top: 1px solid var(--line); border-left: 1px solid var(--line); }
.research-card { min-height: 285px; padding: 28px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); display: flex; flex-direction: column; transition: .25s; }
.research-card:hover { color: white; background: var(--blue); transform: translateY(-4px); }
.research-card:hover p, .research-card:hover .status { color: rgba(255,255,255,.7); }
.card-no { color: var(--pku); font-weight: 800; }
.research-card h3 { margin: auto 0 10px; font-family: var(--serif); font-size: 1.5rem; line-height: 1.3; }
.research-card h3 span { display: block; }
.research-card p { color: var(--muted); font-size: .88rem; }
.status { color: var(--muted); font-size: .72rem; letter-spacing: .08em; }
.work { background: var(--paper); }
.work-list { width: min(100%, var(--max)); margin: auto; border-top: 1px solid var(--ink); }
.work-item { padding: 24px 8px; border-bottom: 1px solid var(--line); display: grid; grid-template-columns: 1fr 3fr 1fr; gap: 26px; align-items: center; }
.work-type { color: var(--pku); font-size: .72rem; font-weight: 700; letter-spacing: .13em; text-transform: uppercase; }
.work-main h3 { margin: 0 0 4px; font-family: var(--serif); font-size: 1.45rem; }
.work-tag { justify-self: end; color: var(--muted); font-size: .78rem; }
.team { color: white; background: var(--blue); }
.team .section-no { color: #efb4b7; }
.team-roster { width: min(100%, var(--max)); margin: auto; display: grid; gap: 44px; }
.team-roster-group { padding-top: 24px; border-top: 1px solid rgba(255,255,255,.24); }
.team-roster-heading { margin-bottom: 20px; display: grid; grid-template-columns: 64px 1fr; align-items: baseline; }
.team-roster-heading > span { color: #efb4b7; font-size: .72rem; font-weight: 700; letter-spacing: .13em; }
.team-roster-heading h3 { margin: 0; font-family: var(--serif); font-size: clamp(1.45rem, 2.2vw, 2.05rem); font-weight: 500; }
.team-roster-heading p { margin: 2px 0 0; color: rgba(255,255,255,.5); font-size: .72rem; letter-spacing: .1em; text-transform: uppercase; }
.team .person-card { min-height: 0; color: var(--ink); }
.team-empty { margin: 0; padding: 22px 24px; border: 1px dashed rgba(255,255,255,.32); color: rgba(255,255,255,.64); }
.alumni-list { margin: 0; padding: 0; border-top: 1px solid var(--ink); display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); list-style: none; }
.alumni-item { padding: 12px 8px; border-bottom: 1px solid var(--line); display: grid; grid-template-columns: minmax(56px, .65fr) minmax(105px, 1.1fr) 22px minmax(90px, 1fr); gap: 9px; align-items: center; }
.alumni-item:nth-child(even) { padding-left: 20px; border-left: 1px solid var(--line); }
.alumni-name { color: var(--pku); font-family: var(--serif); font-size: 1rem; font-weight: 600; }
.alumni-degree, .alumni-destination { color: var(--muted); font-size: .76rem; }
.alumni-arrow { color: var(--pku); font-size: .95rem; text-align: center; }
.team .alumni-list { border-color: rgba(255,255,255,.45); }
.team .alumni-item { border-color: rgba(255,255,255,.22); }
.team .alumni-name { color: white; }
.team .alumni-degree, .team .alumni-destination { color: rgba(255,255,255,.66); }
.team .alumni-arrow { color: #efb4b7; }
.news { background: var(--white); }
.news-heading-main { display: flex; align-items: flex-end; justify-content: space-between; gap: 28px; }
.news-controls { display: flex; align-items: center; gap: 10px; padding-bottom: 6px; }
.news-position { min-width: 72px; color: var(--muted); font-size: .72rem; letter-spacing: .12em; }
.news-position strong { color: var(--pku); }
.news-arrow { width: 46px; height: 46px; border: 1px solid var(--ink); border-radius: 50%; color: var(--ink); background: transparent; cursor: pointer; transition: color .2s, background .2s, opacity .2s; }
.news-arrow:hover:not(:disabled), .news-arrow:focus-visible:not(:disabled) { color: white; background: var(--ink); }
.news-arrow:disabled { opacity: .24; cursor: default; }
.news-carousel { width: min(100%, var(--max)); margin: auto; overflow: hidden; }
.news-track { display: flex; gap: 22px; overflow-x: auto; scroll-snap-type: x mandatory; scroll-behavior: smooth; scrollbar-width: none; outline: none; }
.news-track::-webkit-scrollbar { display: none; }
.news-track:focus-visible { box-shadow: 0 0 0 3px rgba(118,16,24,.15); }
.news-card { flex: 0 0 min(680px, calc(100% - 130px)); min-height: 290px; padding: 28px; border: 1px solid var(--line); background: var(--paper); display: flex; flex-direction: column; scroll-snap-align: start; }
.news-card-feature { color: white; border-color: var(--pku); background: var(--pku); }
.news-card time, .news-kind { margin-right: 16px; color: var(--muted); font-size: .72rem; letter-spacing: .12em; text-transform: uppercase; }
.news-card-feature time, .news-card-feature .news-kind { color: rgba(255,255,255,.72); }
.news-card h3 { max-width: 620px; margin: auto 0 14px; font-family: var(--serif); font-size: clamp(1.55rem, 2.4vw, 2.25rem); line-height: 1.28; font-weight: 500; }
.news-card p { max-width: 620px; margin: 0; color: var(--muted); font-size: .92rem; }
.news-card-feature p { color: rgba(255,255,255,.72); }
.contact { padding: 88px 24px; background: var(--ink); color: white; }
.contact-inner { width: min(100%, var(--max)); margin: auto; }
.contact .section-no { color: #efb4b7; }
.contact h2 { max-width: 760px; margin: 20px 0 16px; font-family: var(--serif); font-size: clamp(1.55rem, 2.6vw, 2.4rem); line-height: 1.3; font-weight: 500; }
.contact-inner > p:not(.section-no) { color: rgba(255,255,255,.65); }
.contact-meta { margin-top: 48px; padding-top: 24px; border-top: 1px solid rgba(255,255,255,.22); display: grid; grid-template-columns: 1fr 1fr; gap: 28px; }
.contact-meta div { display: flex; flex-direction: column; }
.contact-meta span { color: rgba(255,255,255,.45); font-size: .72rem; letter-spacing: .13em; text-transform: uppercase; }
.contact-meta strong { margin-top: 7px; font-family: var(--serif); font-size: 1.08rem; font-weight: 500; }
.contact-meta a { border-bottom: 1px solid rgba(255,255,255,.55); }
.site-footer { width: min(calc(100% - 48px), var(--max)); min-height: 100px; margin: auto; display: grid; grid-template-columns: 1fr 1fr 1fr; align-items: center; font-size: .75rem; }
.site-footer p { text-align: center; color: var(--muted); }
.site-footer > a:last-child { justify-self: end; border-bottom: 1px solid var(--ink); }
.footer-brand .brand-mark { width: 36px; height: 36px; font-size: .65rem; }
.inner-page .site-header { background: rgba(245, 242, 235, .96); border-color: var(--line); backdrop-filter: blur(16px); }
.page-hero { padding: 176px 24px 86px; border-bottom: 1px solid var(--line); background: var(--white); }
.page-hero-inner { width: min(100%, var(--max)); margin: auto; display: grid; grid-template-columns: 1fr 2fr; gap: 34px; }
.page-hero h1 { margin: -10px 0 18px; font-family: var(--serif); font-size: clamp(3.4rem, 7vw, 7rem); line-height: 1; font-weight: 600; letter-spacing: -.045em; }
.page-hero .lead { max-width: 720px; margin: 0; color: var(--muted); font-size: 1.05rem; }
.breadcrumbs { width: min(100%, var(--max)); margin: 0 auto 24px; color: var(--muted); font-size: .78rem; }
.breadcrumbs a { border-bottom: 1px solid var(--line); }
.content-section { padding: 88px 24px; }
.content-section:nth-of-type(even) { background: var(--white); }
.content-inner { width: min(100%, var(--max)); margin: auto; }
.content-heading { margin-bottom: 36px; display: grid; grid-template-columns: 1fr 2fr; gap: 34px; }
.content-heading h2 { margin: 0; font-family: var(--serif); font-size: clamp(2.1rem, 4vw, 3.7rem); line-height: 1.15; font-weight: 600; }
.content-heading p { max-width: 650px; margin: 4px 0 0; color: var(--muted); }
.record-list { border-top: 1px solid var(--ink); }
.record { padding: 28px 8px; border-bottom: 1px solid var(--line); display: grid; grid-template-columns: 120px 1fr 180px; gap: 28px; align-items: start; }
.record-meta { color: var(--pku); font-size: .73rem; font-weight: 700; letter-spacing: .1em; text-transform: uppercase; }
.record h3 { margin: 0 0 8px; font-family: var(--serif); font-size: 1.45rem; font-weight: 600; }
.record p { margin: 0; color: var(--muted); font-size: .9rem; }
.record-side { color: var(--muted); font-size: .78rem; text-align: right; }
.placeholder-banner { padding: 22px 24px; border: 1px dashed rgba(118,16,24,.4); background: rgba(118,16,24,.045); color: var(--muted); }
.placeholder-banner strong { color: var(--pku); }
.people-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.person-card { min-height: 390px; padding: 20px; border: 1px solid var(--line); background: var(--white); transition: transform .2s, box-shadow .2s; }
.person-card:hover, .person-card:focus-visible { transform: translateY(-4px); box-shadow: 0 18px 45px rgba(22,33,44,.09); }
.person-avatar { aspect-ratio: 5 / 7; margin-bottom: 22px; display: grid; place-items: center; overflow: hidden; background: #ebe7de; }
.person-avatar img { width: 100%; height: 100%; object-fit: cover; }
.team-roster .people-grid { grid-template-columns: repeat(auto-fill, 216px); }
.team-roster .person-card { min-height: 0; padding: 16px; }
.team-roster .person-avatar { width: min(100%, 184px); margin: 0 auto 18px; }
.person-card h3 { margin: 0 0 4px; font-family: var(--serif); font-size: 1.35rem; }
.person-card p { margin: 0; color: var(--muted); font-size: .84rem; }
.person-card .profile-link { display: inline-block; margin-top: 15px; color: var(--pku); font-size: .78rem; border-bottom: 1px solid currentColor; }
.profile { padding: 170px 24px 100px; background: var(--white); }
.profile-inner { width: min(100%, 980px); margin: auto; display: grid; grid-template-columns: 280px 1fr; gap: 70px; }
.profile-photo { aspect-ratio: 5 / 7; background: #ebe7de; overflow: hidden; }
.profile-photo img { width: 100%; height: 100%; object-fit: cover; }
.profile-copy h1 { margin: 12px 0 8px; font-family: var(--serif); font-size: clamp(3rem, 6vw, 5.5rem); line-height: 1; font-weight: 600; }
.profile-role { margin: 0 0 34px; color: var(--pku); font-weight: 650; }
.profile-block { padding: 24px 0; border-top: 1px solid var(--line); }
.profile-block h2 { margin: 0 0 8px; font-size: .78rem; letter-spacing: .12em; text-transform: uppercase; }
.profile-block p, .profile-block ul { margin: 0; color: var(--muted); }
.profile-email { color: var(--pku); border-bottom: 1px solid currentColor; }
.profile-block ul { padding-left: 1.2em; }
.profile-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 28px; }
.resource-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.resource-card { min-height: 260px; padding: 28px; border: 1px solid var(--line); background: var(--white); display: flex; flex-direction: column; }
.resource-card span { color: var(--pku); font-size: .72rem; letter-spacing: .13em; text-transform: uppercase; }
.resource-card h3 { margin: auto 0 10px; font-family: var(--serif); font-size: 1.6rem; }
.resource-card p { margin: 0; color: var(--muted); font-size: .88rem; }
.back-link { display: inline-block; margin-top: 35px; color: var(--pku); border-bottom: 1px solid currentColor; font-size: .86rem; }
.reveal { opacity: 0; transform: translateY(18px); transition: opacity .65s ease, transform .65s ease; }
.reveal.visible { opacity: 1; transform: translateY(0); }
.reveal[data-delay="1"] { transition-delay: .11s; }
.reveal[data-delay="2"] { transition-delay: .22s; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } *, *::before, *::after { animation: none !important; transition: none !important; } .reveal { opacity: 1; transform: none; } }
@media (max-width: 900px) {
  .nav-wrap { width: min(calc(100% - 32px), var(--max)); height: 72px; }
  .nav-toggle { display: block; z-index: 2; }
  .site-nav { position: fixed; inset: 0; padding: 110px 32px 32px; background: var(--paper); display: flex; flex-direction: column; align-items: flex-start; gap: 20px; font-family: var(--serif); font-size: 1.45rem; transform: translateX(100%); transition: transform .25s; }
  .site-nav.open { transform: translateX(0); }
  .nav-cta { border: 0; padding: 0; }
  .nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
  .nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
  .nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }
  .hero { min-height: auto; padding-top: 108px; } .hero-inner { grid-template-columns: 1fr; gap: 36px; } .hero-card { min-height: 350px; }
  .section { padding: 68px 24px; } .section-heading { grid-template-columns: 1fr; gap: 16px; }
  .research-grid { grid-template-columns: 1fr; } .research-card { min-height: 240px; }
  .page-hero-inner, .content-heading { grid-template-columns: 1fr; }
  .record { grid-template-columns: 90px 1fr; } .record-side { grid-column: 2; text-align: left; }
  .people-grid, .resource-grid { grid-template-columns: repeat(2, 1fr); }
  .profile-inner { grid-template-columns: 220px 1fr; gap: 38px; }
}
@media (max-width: 620px) {
  .hero h1 { font-size: 2.6rem; } .hero-actions { align-items: flex-start; flex-direction: column; gap: 14px; }
  .work-item { grid-template-columns: 1fr; gap: 8px; } .work-tag { justify-self: start; }
  .contact-meta { grid-template-columns: 1fr; }
  .site-footer { padding: 34px 0; grid-template-columns: 1fr; gap: 24px; } .site-footer p { text-align: left; } .site-footer > a:last-child { justify-self: start; }
  .page-hero { padding-top: 130px; } .page-hero h1 { font-size: 3.3rem; }
  .record { grid-template-columns: 1fr; gap: 8px; } .record-side { grid-column: 1; }
  .people-grid, .resource-grid { grid-template-columns: 1fr; }
  .team-roster-heading { grid-template-columns: 44px 1fr; }
  .alumni-list { grid-template-columns: 1fr; }
  .alumni-item { grid-template-columns: 1fr; gap: 6px; }
  .alumni-item:nth-child(even) { padding-left: 8px; border-left: 0; }
  .alumni-arrow { display: none; }
  .profile { padding-top: 120px; } .profile-inner { grid-template-columns: 1fr; }
  .profile-photo { max-width: 300px; }
  .news-heading-main { align-items: flex-start; flex-direction: column; }
  .news-controls { padding-bottom: 0; }
  .contact { padding: 72px 24px; }
  .news-card { flex-basis: calc(100% - 28px); min-height: 290px; padding: 24px; }
}