/* ========================================
   Research Group Website — PKU Red Theme
   ======================================== */

:root {
  --pku-red: #b93232;
  --pku-red-dark: #922828;
  --pku-red-mid: #d05050;
  --pku-red-soft: #e08a8a;
  --pku-red-wash: rgba(185, 50, 50, 0.06);
  --pku-red-line: rgba(185, 50, 50, 0.18);

  --ink: #1c1416;
  --ink-soft: #3d3235;
  --muted: #6b5f63;
  --muted-light: #9a8e92;

  --paper: #fbfaf9;
  --paper-warm: #f7f3f1;
  --white: #ffffff;
  --border: rgba(28, 20, 22, 0.08);

  --font-display: "Noto Serif SC", "Songti SC", "SimSun", serif;
  --font-body: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-en: "Cormorant Garamond", "Noto Serif SC", serif;

  --nav-h: 72px;
  --footer-h: 58px;
  --max: 1120px;
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
  --shadow-soft: 0 12px 40px rgba(185, 50, 50, 0.1);
}

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body {
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.7;
  color: var(--ink);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
  overflow-x: clip;
  padding-bottom: var(--footer-h);
  min-width: 0;
}

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

/* Prevent long words / citations from forcing horizontal scroll */
p,
li,
dd,
figcaption,
.pub-citation,
.research-refs li,
.block-body,
.section-desc {
  overflow-wrap: anywhere;
  word-break: break-word;
}

a {
  color: inherit;
  text-decoration: none;
}

ul,
ol {
  list-style: none;
}

/* ---------- Nav ---------- */

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--nav-h);
  transition: background 0.35s var(--ease), box-shadow 0.35s var(--ease),
    backdrop-filter 0.35s var(--ease);
}

.site-header.is-scrolled,
.site-header.is-solid {
  background: rgba(251, 250, 249, 0.92);
  backdrop-filter: blur(16px);
  box-shadow: 0 1px 0 var(--border);
}

.site-header.is-scrolled .brand-name,
.site-header.is-scrolled .nav-link,
.site-header.is-solid .brand-name,
.site-header.is-solid .nav-link {
  color: var(--ink);
}

.site-header.is-scrolled .nav-link:hover,
.site-header.is-scrolled .nav-link.is-active,
.site-header.is-solid .nav-link:hover,
.site-header.is-solid .nav-link.is-active {
  color: var(--pku-red);
}

.site-header.is-scrolled .nav-toggle span,
.site-header.is-solid .nav-toggle span {
  background: var(--ink);
}

.nav-inner {
  max-width: calc(var(--max) + 80px);
  margin: 0 auto;
  padding: 0 28px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 1;
  min-width: 0;
  z-index: 2;
}

.brand-mark {
  width: 46px;
  height: 46px;
  border-radius: 50%;
  background: linear-gradient(145deg, var(--pku-red-mid), var(--pku-red-dark));
  display: grid;
  place-items: center;
  color: var(--white);
  font-family: var(--font-body);
  font-weight: 700;
  font-size: 10px;
  letter-spacing: 0.01em;
  line-height: 1;
  box-shadow: 0 4px 14px rgba(185, 50, 50, 0.28);
  flex-shrink: 0;
}

.brand-name {
  font-family: var(--font-display);
  font-size: clamp(14px, 2.4vw, 18px);
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--white);
  transition: color 0.3s;
  line-height: 1.25;
  min-width: 0;
}

.brand-name span {
  display: block;
  font-family: var(--font-en);
  font-size: 13px;
  font-weight: 500;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  opacity: 0.72;
  margin-top: 1px;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-link {
  position: relative;
  padding: 8px 12px;
  font-size: 16.5px;
  font-weight: 500;
  letter-spacing: 0.02em;
  color: rgba(255, 255, 255, 0.88);
  transition: color 0.25s;
  white-space: nowrap;
}

.nav-link::after {
  content: "";
  position: absolute;
  left: 11px;
  right: 11px;
  bottom: 4px;
  height: 1.5px;
  background: currentColor;
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.3s var(--ease);
  opacity: 0.85;
}

.nav-link:hover,
.nav-link.is-active {
  color: #fff;
}

.nav-link:hover::after,
.nav-link.is-active::after {
  transform: scaleX(1);
}

.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  border: none;
  background: transparent;
  cursor: pointer;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 6px;
  position: relative;
  z-index: 120;
  flex-shrink: 0;
  -webkit-tap-highlight-color: transparent;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 1.5px;
  background: var(--white);
  transition: transform 0.3s, opacity 0.3s, background 0.3s;
}

.nav-toggle.is-open span:nth-child(1) {
  transform: translateY(7.5px) rotate(45deg);
}

.nav-toggle.is-open span:nth-child(2) {
  opacity: 0;
}

.nav-toggle.is-open span:nth-child(3) {
  transform: translateY(-7.5px) rotate(-45deg);
}

/* ---------- Hero ---------- */

.hero {
  position: relative;
  min-height: min(78vh, 820px);
  display: flex;
  align-items: flex-end;
  color: var(--ink);
  overflow: hidden;
  background: #fff;
  padding-top: var(--nav-h);
}

.hero-bg {
  position: absolute;
  inset: 0;
  background-color: #fff;
  background-image: url("../photos/home.jpg");
  background-position: center 28%;
  background-repeat: no-repeat;
  background-size: min(780px, 68%) auto;
  z-index: 0;
}

.hero-content {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: calc(var(--max) + 80px);
  margin: 0 auto;
  padding: 28px 28px 40px;
  background: linear-gradient(
    to top,
    rgba(255, 255, 255, 0.96) 0%,
    rgba(255, 255, 255, 0.88) 55%,
    rgba(255, 255, 255, 0) 100%
  );
}

.hero-brand {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  font-weight: 700;
  letter-spacing: 0.06em;
  line-height: 1.2;
  margin-bottom: 10px;
  color: var(--ink);
}

.hero-brand em {
  font-style: normal;
  color: var(--pku-red);
  font-weight: 500;
}

.hero-tagline {
  font-size: clamp(0.95rem, 1.5vw, 1.05rem);
  font-weight: 400;
  letter-spacing: 0.04em;
  color: var(--muted);
  max-width: 36em;
  margin-bottom: 24px;
  line-height: 1.75;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.hero .btn-primary {
  background: var(--pku-red);
  color: var(--white);
}

.hero .btn-primary:hover {
  background: var(--pku-red-dark);
}

.hero .btn-ghost {
  color: var(--pku-red);
  border: 1px solid var(--pku-red-line);
}

.hero .btn-ghost:hover {
  border-color: var(--pku-red);
  background: var(--pku-red-wash);
}

/* Homepage desktop nav: same bar as other pages; text stays dark (not white) */
@media (min-width: 961px) {
  .page-home .site-header.is-solid .brand-name,
  .page-home .site-header.is-solid .nav-link,
  .page-home .site-header.is-scrolled .brand-name,
  .page-home .site-header.is-scrolled .nav-link {
    color: var(--ink);
  }

  .page-home .site-header.is-solid .nav-link:hover,
  .page-home .site-header.is-solid .nav-link.is-active,
  .page-home .site-header.is-scrolled .nav-link:hover,
  .page-home .site-header.is-scrolled .nav-link.is-active {
    color: var(--pku-red);
  }

  .page-home .site-header.is-solid .nav-toggle span,
  .page-home .site-header.is-scrolled .nav-toggle span {
    background: var(--ink);
  }
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  font-family: var(--font-body);
  font-size: 14px;
  font-weight: 500;
  letter-spacing: 0.04em;
  border: none;
  cursor: pointer;
  transition: background 0.2s, color 0.2s, border-color 0.2s;
}

.btn-primary {
  background: var(--white);
  color: var(--pku-red);
}

.btn-primary:hover {
  background: #f8eaea;
}

.btn-ghost {
  background: transparent;
  color: var(--white);
  border: 1px solid rgba(255, 255, 255, 0.4);
}

.btn-ghost:hover {
  border-color: rgba(255, 255, 255, 0.75);
  background: rgba(255, 255, 255, 0.06);
}

.btn-red {
  background: var(--pku-red);
  color: var(--white);
}

.btn-red:hover {
  background: var(--pku-red-dark);
}

.btn-outline {
  background: transparent;
  color: var(--pku-red);
  border: 1px solid var(--pku-red-line);
}

.btn-outline:hover {
  border-color: var(--pku-red);
  background: var(--pku-red-wash);
}

/* ---------- Layout ---------- */

body:not(.page-home) main > .section:first-child {
  padding-top: calc(var(--nav-h) + 48px);
}

.section {
  padding: 88px 28px;
}

.section-alt {
  background: var(--paper-warm);
}

.section-compact {
  padding: 36px 28px;
}

.container {
  max-width: var(--max);
  margin: 0 auto;
}

.section-head {
  margin-bottom: 48px;
  max-width: 40em;
}

.section-head:has(+ .section-note) {
  margin-bottom: 10px;
}

.section-label {
  display: inline-block;
  font-family: var(--font-en);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--pku-red);
  margin-bottom: 10px;
}

.section-title {
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 3vw, 2.1rem);
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--ink);
  margin-bottom: 14px;
  line-height: 1.35;
}

.section-desc {
  color: var(--muted);
  font-size: 1rem;
  line-height: 1.8;
}

.section-note {
  margin-top: 0;
  margin-bottom: 28px;
  padding: 12px 16px;
  width: 100%;
  box-sizing: border-box;
  font-size: 0.92rem;
  line-height: 1.75;
  color: var(--muted-light);
  background: var(--pku-red-wash);
  border-left: 3px solid var(--pku-red);
}

.divider {
  width: 48px;
  height: 2px;
  background: var(--pku-red);
  margin: 20px 0 0;
}

/* ---------- Mentor bar (home) ---------- */

.mentor-bar {
  display: block;
  background: linear-gradient(
    105deg,
    var(--pku-red-dark) 0%,
    #a02c2c 45%,
    var(--pku-red) 100%
  );
  color: var(--white);
  text-decoration: none;
  transition: filter 0.3s var(--ease), background 0.3s var(--ease);
}

.mentor-bar:hover {
  filter: brightness(1.06);
  background: linear-gradient(
    105deg,
    #7a2020 0%,
    var(--pku-red-dark) 45%,
    var(--pku-red-mid) 100%
  );
}

.mentor-bar-inner {
  display: flex;
  align-items: center;
  gap: 28px;
  padding-top: 32px;
  padding-bottom: 32px;
}

.mentor-bar-portrait {
  flex-shrink: 0;
  width: 76px;
  height: 76px;
  border-radius: 50%;
  overflow: hidden;
  border: 2px solid rgba(255, 255, 255, 0.45);
}

.mentor-bar-portrait img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.mentor-bar-text {
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.mentor-bar-label {
  font-family: var(--font-en);
  font-size: 13px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: rgba(255, 255, 255, 0.78);
}

.mentor-bar-text strong {
  font-family: var(--font-display);
  font-size: 1.55rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--white);
}

.mentor-bar-meta {
  font-size: 1rem;
  color: rgba(255, 255, 255, 0.82);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.mentor-bar-cta {
  flex-shrink: 0;
  font-size: 1.02rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  color: var(--white);
  padding: 14px 22px;
  border: 1px solid rgba(255, 255, 255, 0.45);
  transition: background 0.25s, border-color 0.25s;
}

.mentor-bar:hover .mentor-bar-cta {
  background: rgba(255, 255, 255, 0.14);
  border-color: rgba(255, 255, 255, 0.85);
}

.mentor-bar-cta::after {
  content: " →";
}

/* ---------- Home intro ---------- */

.intro-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 64px;
  align-items: center;
}

.intro-text p {
  color: var(--muted);
  margin-bottom: 1.2em;
  font-size: 1.02rem;
}

.intro-text p:last-child {
  margin-bottom: 0;
}

.intro-aside {
  position: relative;
  padding: 32px 28px;
  background: var(--pku-red);
  color: var(--white);
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.intro-aside-label {
  font-family: var(--font-en);
  font-size: 11px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  opacity: 0.65;
  margin-bottom: 10px;
}

.intro-aside-text {
  font-family: var(--font-display);
  font-size: 1.35rem;
  letter-spacing: 0.04em;
  line-height: 1.55;
  padding-left: 1em;
  text-indent: -1em;
}

/* ---------- Focus areas (home) ---------- */

.section:has(> .focus-panel) {
  padding-bottom: 0;
}

.focus-panel {
  background: var(--paper-warm);
  margin-left: -28px;
  margin-right: -28px;
  margin-top: 8px;
  padding: 32px 28px 88px;
}

.focus-list {
  display: grid;
  gap: 0;
  border-top: 1px solid var(--border);
}

.focus-item {
  display: grid;
  grid-template-columns: 72px 1fr;
  gap: 24px;
  align-items: baseline;
  padding: 24px 0;
  border-bottom: 1px solid var(--border);
}

.focus-item:hover .focus-body h3 {
  color: var(--pku-red);
}

.focus-num {
  font-family: var(--font-en);
  font-size: 14px;
  color: var(--pku-red);
  letter-spacing: 0.08em;
}

.focus-body h3 {
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  margin-bottom: 6px;
  transition: color 0.2s;
}

.focus-body p {
  color: var(--muted);
  font-size: 0.95rem;
  max-width: 42em;
}

/* ---------- Placeholder blocks ---------- */

.placeholder {
  border: 1px dashed var(--pku-red-line);
  background: var(--pku-red-wash);
  padding: 48px 32px;
  text-align: center;
  color: var(--muted);
}

.placeholder-icon {
  width: 40px;
  height: 40px;
  margin: 0 auto 16px;
  border: 1.5px solid var(--pku-red-soft);
  border-radius: 50%;
  display: grid;
  place-items: center;
  color: var(--pku-red);
  font-size: 18px;
}

.placeholder strong {
  display: block;
  font-family: var(--font-display);
  font-size: 1.05rem;
  color: var(--ink-soft);
  font-weight: 600;
  margin-bottom: 6px;
  letter-spacing: 0.04em;
}

.placeholder p {
  font-size: 0.9rem;
  color: var(--muted-light);
}

/* ---------- Content blocks ---------- */

.content-stack {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.block {
  padding-bottom: 32px;
  border-bottom: 1px solid var(--border);
}

.block:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.block-title {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  margin-bottom: 12px;
  color: var(--ink);
}

.block-title::before {
  content: "";
  display: inline-block;
  width: 8px;
  height: 8px;
  background: var(--pku-red);
  margin-right: 12px;
  vertical-align: middle;
  transform: translateY(-1px);
}

.block p,
.block-body {
  color: var(--muted);
  line-height: 1.85;
}

.block-body a {
  color: var(--pku-red);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.block-body a:hover {
  color: var(--pku-red-dark);
}

.project-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-top: 4px;
}

.project-list li {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--border);
}

.project-list li:last-child {
  padding-bottom: 0;
  border-bottom: none;
}

.project-list strong {
  font-family: var(--font-display);
  font-size: 1.02rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--ink);
  line-height: 1.45;
}

.project-list span {
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.65;
}

/* Research directions */
.dir-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
}

.dir-cell {
  display: block;
  background: var(--paper);
  padding: 36px 32px;
  transition: background 0.3s, color 0.2s;
  text-decoration: none;
  color: inherit;
}

a.dir-cell:hover {
  background: var(--paper-warm);
}

a.dir-cell:hover h3 {
  color: var(--pku-red);
}

.dir-cell h3 {
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  margin-bottom: 10px;
  color: var(--ink);
  transition: color 0.2s;
}

.dir-cell p {
  color: var(--muted);
  font-size: 0.95rem;
}

.dir-index {
  font-family: var(--font-en);
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--pku-red);
  margin-bottom: 14px;
}

.research-detail {
  padding: 56px 0;
  border-bottom: 1px solid var(--border);
  scroll-margin-top: calc(var(--nav-h) + 24px);
}

.research-detail:first-child {
  padding-top: 0;
}

.research-detail:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.research-detail .section-title {
  margin-bottom: 20px;
}

.research-detail-body {
  max-width: 46em;
  margin-bottom: 28px;
}

.research-detail-body p {
  color: var(--muted);
  font-size: 1rem;
  line-height: 1.85;
  margin-bottom: 1em;
}

.research-detail-body p:last-child {
  margin-bottom: 0;
}

.research-figure {
  margin: 0 0 28px;
  text-align: center;
}

.research-figure img {
  width: 100%;
  max-width: 860px;
  height: auto;
  aspect-ratio: auto;
  object-fit: contain;
  display: block;
  margin: 0 auto;
  border: 1px solid var(--border);
  background: var(--white);
}

.research-figure-md img {
  max-width: 620px;
}

.research-figure-sm img {
  max-width: 480px;
}

.research-figure figcaption {
  margin-top: 10px;
  font-size: 0.88rem;
  color: var(--muted-light);
  letter-spacing: 0.02em;
}

.research-ref-title {
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--ink);
  margin: 8px 0 14px;
}

.research-refs {
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding-left: 1.15em;
  list-style: disc;
  max-width: 52em;
}

.research-refs li {
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.7;
  padding-left: 0.15em;
}

.research-refs li::marker {
  color: var(--pku-red-soft);
}

.research-refs em {
  font-style: italic;
  color: var(--ink-soft);
}

/* Publications / page anchor nav */
body:not(.page-home) main > .section.section-pubs:first-child {
  padding-top: calc(var(--nav-h) + 20px);
}

main.has-anchor-nav {
  padding-top: var(--nav-h);
}

main.has-anchor-nav > .section:first-of-type {
  padding-top: 36px;
}

body:not(.page-home) main.has-anchor-nav > .section:first-of-type {
  padding-top: 36px;
}

.pub-filters-sticky {
  position: sticky;
  top: var(--nav-h);
  z-index: 50;
  background: rgba(251, 250, 249, 0.96);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border);
  margin: 0 -28px 36px;
  padding: 14px 28px;
}

main.has-anchor-nav > .pub-filters-sticky {
  margin: 0;
  padding: 14px 28px;
}

.pub-filters {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.filter-btn {
  padding: 8px 18px;
  font-family: var(--font-body);
  font-size: 13px;
  font-weight: 500;
  letter-spacing: 0.04em;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  transition: all 0.25s;
}

.filter-btn:hover,
.filter-btn.is-active {
  border-color: var(--pku-red);
  color: var(--pku-red);
  background: var(--pku-red-wash);
}

.pub-list {
  display: flex;
  flex-direction: column;
  gap: 40px;
}

.pub-year-group,
#pub-top,
.facility-anchor,
#facility-top {
  scroll-margin-top: calc(var(--nav-h) + 88px);
}

.pub-year-title {
  font-family: var(--font-display);
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--ink);
  margin-bottom: 8px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--pku-red);
  display: inline-block;
}

.pub-item {
  display: block;
  padding: 18px 0;
  border-bottom: 1px solid var(--border);
}

.pub-year-group .pub-item:last-child {
  border-bottom: none;
}

.pub-citation {
  font-size: 0.95rem;
  line-height: 1.75;
  color: var(--ink-soft);
}

.pub-citation em {
  font-style: italic;
  color: var(--ink);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.pub-citation strong {
  font-weight: 700;
  color: var(--ink);
}

.pub-num {
  display: inline-block;
  min-width: 2.4em;
  font-family: var(--font-en);
  font-weight: 600;
  color: var(--pku-red);
  margin-right: 6px;
}

.pub-pdf {
  display: inline-block;
  margin-left: 10px;
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--pku-red);
  text-decoration: underline;
  text-underline-offset: 3px;
  white-space: nowrap;
}

.pub-pdf:hover {
  color: var(--pku-red-dark);
}

.pub-empty {
  padding: 40px 0;
  color: var(--muted-light);
  font-size: 0.95rem;
  text-align: center;
  border: 1px dashed var(--pku-red-line);
  background: var(--pku-red-wash);
}

/* Facility / Software grids */
.facility-grid,
.software-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

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

.facility-item,
.software-item {
  padding-top: 20px;
  border-top: 2px solid var(--pku-red);
}

.facility-item h3,
.software-item h3 {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  margin: 12px 0 8px;
}

.facility-item p,
.software-item p {
  color: var(--muted);
  font-size: 0.92rem;
}

.facility-stack {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.facility-entry {
  padding: 36px 0;
  border-bottom: 1px solid var(--border);
}

.facility-entry:first-child {
  padding-top: 0;
}

.facility-entry:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.facility-entry .item-tag {
  display: inline-block;
  margin-bottom: 10px;
}

.facility-entry h3 {
  font-family: var(--font-display);
  font-size: clamp(1.15rem, 2vw, 1.35rem);
  font-weight: 600;
  letter-spacing: 0.03em;
  line-height: 1.4;
  color: var(--ink);
  margin-bottom: 8px;
}

.facility-entry > p {
  color: var(--muted);
  font-size: 0.95rem;
  line-height: 1.75;
  max-width: 42em;
  margin-bottom: 20px;
}

.facility-figure {
  margin: 0;
  padding: 0;
  border: none;
  background: transparent;
  text-align: center;
}

.facility-figure img {
  width: 100%;
  max-width: 880px;
  height: auto;
  aspect-ratio: auto;
  object-fit: contain;
  display: block;
  margin-left: auto;
  margin-right: auto;
  border: 1px solid var(--border);
  background: var(--white);
}

.facility-figure-md img {
  max-width: 620px;
}

.facility-figure-sm img {
  max-width: 480px;
}

.facility-gallery {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 28px;
}

.facility-gallery-item {
  margin: 0;
  background: var(--white);
  border: 1px solid var(--border);
  padding: 14px;
}

.facility-gallery-item img {
  width: 100%;
  height: auto;
  aspect-ratio: auto;
  object-fit: contain;
  display: block;
  margin-bottom: 12px;
}

.facility-gallery-item figcaption {
  font-family: var(--font-en);
  font-size: 0.9rem;
  color: var(--muted);
  letter-spacing: 0.02em;
  line-height: 1.45;
}

.software-list {
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-top: 6px;
}

.software-list li {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
}

.software-list li:last-child {
  padding-bottom: 0;
  border-bottom: none;
}

.software-list a {
  color: var(--pku-red);
  font-weight: 600;
  font-size: 0.98rem;
  text-decoration: underline;
  text-underline-offset: 3px;
}

.software-list a:hover {
  color: var(--pku-red-dark);
}

.software-list span {
  color: var(--muted);
  font-size: 0.88rem;
  line-height: 1.55;
}

.item-tag {
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--pku-red-soft);
  font-family: var(--font-en);
}

/* Teaching */
.course-list {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.course-item {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: 28px;
  padding: 28px 0;
  border-bottom: 1px solid var(--border);
}

.course-term {
  font-family: var(--font-en);
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--pku-red);
  padding-top: 4px;
}

.course-item h3 {
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 6px;
}

.course-item p {
  color: var(--muted);
  font-size: 0.92rem;
}

/* People */
.people-lead {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 48px;
  margin-bottom: 72px;
  padding-bottom: 56px;
  border-bottom: 1px solid var(--border);
}

.avatar {
  aspect-ratio: 3 / 4;
  background: linear-gradient(
    160deg,
    var(--paper-warm),
    var(--pku-red-wash)
  );
  border: 1px solid var(--border);
  display: grid;
  place-items: center;
  color: var(--muted-light);
  font-size: 13px;
  letter-spacing: 0.08em;
  overflow: hidden;
}

.avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.avatar-sm {
  aspect-ratio: 3 / 4;
  width: 88%;
  max-width: 200px;
}

.person-info h2 {
  font-family: var(--font-display);
  font-size: 1.6rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  margin-bottom: 6px;
}

.person-info .person-role {
  display: inline-block;
  color: var(--pku-red-dark);
  font-size: 1.02rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  line-height: 1.5;
  margin-bottom: 20px;
  padding: 8px 14px;
  background: var(--pku-red-wash);
  border-left: 3px solid var(--pku-red);
}

.person-info p {
  color: var(--muted);
  margin-bottom: 0.8em;
}

.person-subtitle {
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  margin: 1.4em 0 0.7em;
  color: var(--ink);
}

.person-honors {
  color: var(--muted);
  line-height: 1.75;
  padding-left: 1.15em;
  list-style: disc;
}

.person-honors li {
  margin-bottom: 0.55em;
  padding-left: 0.2em;
}

.person-honors li::marker {
  color: var(--pku-red-soft);
}

.person-timeline {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 0.4em;
}

.person-timeline li {
  display: grid;
  grid-template-columns: 168px 1fr;
  gap: 16px;
  color: var(--muted);
  line-height: 1.7;
}

.timeline-term {
  font-family: var(--font-en);
  font-size: 1.22rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  color: var(--pku-red);
  padding-top: 0;
  white-space: nowrap;
}

.timeline-body {
  min-width: 0;
}

.people-group-title {
  font-family: var(--font-display);
  font-size: 1.3rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  margin-bottom: 28px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--pku-red);
  display: inline-block;
}

.people-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 32px 24px;
  margin-bottom: 64px;
}

.people-card {
  text-align: left;
}

.people-card .avatar {
  margin-bottom: 14px;
}

.people-card h3 {
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  margin-bottom: 4px;
}

.people-card .role {
  font-size: 0.85rem;
  color: var(--muted);
}

/* Positions */
.job-list {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.job-item {
  padding: 32px;
  border-left: 3px solid var(--pku-red);
  background: var(--white);
  box-shadow: var(--shadow-soft);
}

.job-item h3 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  margin-bottom: 8px;
}

.job-meta {
  font-size: 0.88rem;
  color: var(--pku-red);
  margin-bottom: 14px;
  letter-spacing: 0.04em;
}

.job-item p {
  color: var(--muted);
  font-size: 0.95rem;
  margin-bottom: 20px;
}

/* Contact */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
}

.contact-info dt {
  font-family: var(--font-en);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--pku-red);
  margin-bottom: 6px;
  margin-top: 24px;
}

.contact-info dt:first-child {
  margin-top: 0;
}

.contact-info dd {
  color: var(--ink-soft);
  font-size: 1.02rem;
  line-height: 1.6;
}

.contact-form {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.contact-form .form-honey {
  position: absolute;
  left: -9999px;
  opacity: 0;
  height: 0;
  width: 0;
  overflow: hidden;
  pointer-events: none;
}

.contact-form .form-note {
  font-size: 0.88rem;
  margin-top: 4px;
  color: var(--muted);
}

.contact-form .form-note.is-success {
  color: var(--pku-red);
}

.contact-form .form-note.is-error {
  color: #a33;
}

.contact-form .btn:disabled {
  opacity: 0.65;
  cursor: not-allowed;
}

.form-row {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.form-row label {
  font-size: 13px;
  font-weight: 500;
  color: var(--ink-soft);
  letter-spacing: 0.04em;
}

.form-row input,
.form-row textarea {
  font-family: var(--font-body);
  font-size: 15px;
  padding: 12px 14px;
  border: 1px solid var(--border);
  background: var(--white);
  color: var(--ink);
  outline: none;
  transition: border-color 0.25s;
  resize: vertical;
}

.form-row input:focus,
.form-row textarea:focus {
  border-color: var(--pku-red-soft);
}

.form-row textarea {
  min-height: 140px;
}

.map-embed {
  margin-top: 64px;
  border: 1px solid var(--border);
  overflow: hidden;
  background: #fff;
}

.map-embed img {
  width: 100%;
  height: auto;
  aspect-ratio: auto;
  object-fit: contain;
  display: block;
}

/* ---------- CTA band ---------- */

.cta-band {
  position: relative;
  padding: 72px 28px;
  color: var(--white);
  overflow: hidden;
}

.cta-band-bg {
  position: absolute;
  inset: 0;
  background: linear-gradient(120deg, var(--pku-red-dark), var(--pku-red) 60%, var(--pku-red-mid));
}

.cta-inner {
  position: relative;
  z-index: 1;
  max-width: var(--max);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
  flex-wrap: wrap;
}

.cta-inner h2 {
  font-family: var(--font-display);
  font-size: clamp(1.4rem, 3vw, 1.85rem);
  font-weight: 700;
  letter-spacing: 0.06em;
  margin-bottom: 8px;
}

.cta-inner p {
  color: rgba(255, 255, 255, 0.75);
  font-size: 0.98rem;
}

/* ---------- Footer ---------- */

.site-footer {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 60;
  background: #1a0e11;
  color: rgba(255, 255, 255, 0.55);
  padding: 10px 28px;
  box-shadow: 0 -4px 16px rgba(26, 14, 17, 0.14);
}

.footer-simple {
  max-width: var(--max);
  margin: 0 auto;
  text-align: center;
  font-family: var(--font-en);
  font-size: 0.82rem;
  line-height: 1.3;
  letter-spacing: 0.02em;
}

.footer-simple p + p {
  margin-top: 2px;
  font-size: 0.75rem;
  color: rgba(255, 255, 255, 0.38);
}

/* ---------- Reveal on scroll ---------- */

.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s var(--ease), transform 0.7s var(--ease);
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* ---------- Responsive ---------- */

@media (max-width: 1100px) {
  .nav-link {
    padding: 8px 8px;
    font-size: 15px;
  }

  .nav-inner {
    gap: 12px;
  }
}

@media (max-width: 960px) {
  .nav-toggle {
    display: flex;
  }

  .site-header nav {
    position: static;
  }

  .nav-list {
    position: fixed;
    top: var(--nav-h);
    right: 0;
    left: auto;
    bottom: auto;
    z-index: 110;
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
    align-items: stretch;
    gap: 0;
    width: min(168px, 42vw);
    max-width: 168px;
    max-height: calc(100vh - var(--nav-h) - 12px);
    margin: 0;
    padding: 6px 0;
    background: rgba(28, 8, 12, 0.97);
    box-shadow: -8px 12px 28px rgba(0, 0, 0, 0.28);
    border-left: 1px solid rgba(255, 255, 255, 0.1);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translateX(12px);
    transition: opacity 0.25s var(--ease), visibility 0.25s, transform 0.25s var(--ease);
    overflow: visible;
  }

  .nav-list.is-open {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateX(0);
  }

  /* Keep header bar readable when menu is open */
  .site-header:has(.nav-list.is-open) {
    background: rgba(28, 8, 12, 0.96);
    box-shadow: 0 1px 0 rgba(255, 255, 255, 0.08);
  }

  .site-header:has(.nav-list.is-open) .brand-name,
  .page-home .site-header:has(.nav-list.is-open) .brand-name {
    color: rgba(255, 255, 255, 0.92);
  }

  .site-header:has(.nav-list.is-open) .nav-toggle span,
  .page-home .site-header:has(.nav-list.is-open) .nav-toggle span {
    background: #fff;
  }

  .nav-list > li {
    width: 100%;
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  }

  .nav-list > li:last-child {
    border-bottom: none;
  }

  .nav-link {
    display: block;
    width: 100%;
    box-sizing: border-box;
    font-size: 0.95rem;
    font-weight: 500;
    letter-spacing: 0.04em;
    padding: 11px 16px;
    color: rgba(255, 255, 255, 0.9);
    text-align: left;
    white-space: nowrap;
  }

  .nav-link::after {
    display: none;
  }

  .nav-link:hover,
  .nav-link.is-active {
    color: #fff;
    background: rgba(185, 50, 50, 0.28);
  }

  .nav-link.is-active {
    color: #f0c4c4;
    border-left: 3px solid var(--pku-red-mid);
    padding-left: 13px;
  }

  .site-header.is-scrolled .nav-link,
  .site-header.is-solid .nav-link {
    color: rgba(255, 255, 255, 0.9);
  }

  .site-header.is-scrolled .nav-link.is-active,
  .site-header.is-solid .nav-link.is-active,
  .site-header.is-scrolled .nav-link:hover,
  .site-header.is-solid .nav-link:hover {
    color: #fff;
  }

  /* Homepage mobile menu: white links like other pages */
  .page-home .nav-list.is-open .nav-link {
    color: rgba(255, 255, 255, 0.9);
  }

  .page-home .nav-list.is-open .nav-link:hover,
  .page-home .nav-list.is-open .nav-link.is-active {
    color: #fff;
  }

  .page-home .nav-list.is-open .nav-link.is-active {
    color: #f0c4c4;
  }

  .intro-grid,
  .contact-grid,
  .people-lead {
    grid-template-columns: 1fr;
    gap: 36px;
  }

  .people-lead .avatar {
    max-width: 220px;
    width: 100%;
    margin: 0 auto;
  }

  .mentor-bar-inner {
    flex-wrap: wrap;
    gap: 14px 16px;
  }

  .mentor-bar-meta {
    white-space: normal;
  }

  .mentor-bar-cta {
    width: 100%;
    text-align: center;
  }

  .dir-grid {
    grid-template-columns: 1fr;
  }

  .dir-cell {
    padding: 28px 24px;
  }

  .facility-grid,
  .software-grid,
  .facility-gallery {
    grid-template-columns: 1fr 1fr;
  }

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

  .focus-item {
    grid-template-columns: 48px 1fr;
    gap: 16px;
  }

  .course-item {
    grid-template-columns: 1fr;
    gap: 8px;
  }

  .person-timeline li {
    grid-template-columns: 1fr;
    gap: 4px;
  }

  .timeline-term {
    white-space: normal;
  }

  .research-detail {
    padding: 44px 0;
  }

  .job-item {
    padding: 24px 20px;
  }

  .cta-inner {
    flex-direction: column;
    align-items: flex-start;
  }

  .hero-bg {
    background-size: min(640px, 78%) auto;
  }
}

@media (max-width: 600px) {
  :root {
    --footer-h: 72px;
    --nav-h: 64px;
  }

  .section {
    padding: 56px 16px;
  }

  .section-head {
    margin-bottom: 32px;
  }

  .pub-filters-sticky {
    margin-left: -16px;
    margin-right: -16px;
    padding: 12px 16px;
  }

  main.has-anchor-nav > .pub-filters-sticky {
    margin: 0;
    padding: 12px 16px;
  }

  .pub-filters {
    gap: 6px;
  }

  .filter-btn {
    padding: 7px 12px;
    font-size: 12px;
  }

  .pub-year-group,
  #pub-top,
  .facility-anchor,
  #facility-top {
    scroll-margin-top: calc(var(--nav-h) + 108px);
  }

  .focus-panel {
    margin-left: -16px;
    margin-right: -16px;
    padding: 24px 16px 56px;
  }

  .section-compact {
    padding: 24px 16px;
  }

  body:not(.page-home) main > .section:first-child {
    padding-top: calc(var(--nav-h) + 28px);
  }

  .hero {
    min-height: min(52vh, 520px);
    padding-top: var(--nav-h);
  }

  .hero-bg {
    background-size: min(100%, 92vw) auto;
    background-position: center 18%;
  }

  .hero-content {
    padding: 16px 16px 28px;
  }

  .hero-actions {
    width: 100%;
  }

  .hero-actions .btn {
    flex: 1 1 auto;
    min-width: 0;
  }

  .facility-grid,
  .software-grid,
  .facility-gallery,
  .people-grid {
    grid-template-columns: 1fr;
  }

  .facility-gallery {
    gap: 16px;
  }

  .facility-gallery-item {
    padding: 10px;
  }

  .facility-entry {
    padding: 28px 0;
  }

  .nav-inner {
    padding: 0 16px;
  }

  .nav-list {
    width: min(148px, 46vw);
    max-width: 148px;
  }

  .nav-link {
    padding: 10px 14px;
    font-size: 0.92rem;
  }

  .nav-link.is-active {
    padding-left: 11px;
  }

  .brand-mark {
    width: 40px;
    height: 40px;
    font-size: 9px;
  }

  .brand-name {
    font-size: 14px;
  }

  .brand-name span {
    display: none;
  }

  .dir-cell {
    padding: 24px 18px;
  }

  .research-detail {
    padding: 36px 0;
  }

  .research-figure,
  .facility-figure {
    margin-bottom: 20px;
  }

  .research-refs {
    padding-left: 1em;
    max-width: 100%;
  }

  .research-refs li,
  .pub-citation {
    font-size: 0.86rem;
  }

  .pub-pdf {
    display: inline;
    white-space: normal;
    margin-left: 6px;
  }

  .people-lead {
    gap: 24px;
    margin-bottom: 48px;
    padding-bottom: 36px;
  }

  .people-lead .avatar {
    max-width: 180px;
  }

  .avatar-sm {
    width: 72%;
    max-width: 160px;
    margin-left: auto;
    margin-right: auto;
  }

  .people-card {
    text-align: center;
  }

  .people-card .avatar {
    margin-left: auto;
    margin-right: auto;
  }

  .person-info h2 {
    font-size: 1.35rem;
  }

  .person-info .person-role {
    font-size: 0.95rem;
    padding: 6px 10px;
  }

  .job-item {
    padding: 20px 16px;
  }

  .job-item h3 {
    font-size: 1.1rem;
  }

  .contact-grid {
    gap: 36px;
  }

  .map-embed {
    margin-top: 40px;
  }

  .cta-band {
    padding: 48px 16px;
  }

  .site-footer {
    padding: 10px 16px;
  }

  .footer-simple {
    font-size: 0.72rem;
    line-height: 1.4;
  }

  .mentor-bar-inner {
    padding-top: 24px;
    padding-bottom: 24px;
  }

  .mentor-bar-portrait {
    width: 64px;
    height: 64px;
  }

  .mentor-bar-text strong {
    font-size: 1.3rem;
  }

  .intro-aside {
    padding: 24px 20px;
  }

  .intro-aside-text {
    font-size: 1.15rem;
  }

  .placeholder {
    padding: 32px 20px;
  }
}

/* Very small phones */
@media (max-width: 380px) {
  .brand-name {
    font-size: 12.5px;
  }

  .hero-actions {
    flex-direction: column;
  }

  .hero-actions .btn {
    width: 100%;
  }

  .section {
    padding: 48px 14px;
  }
}