:root {
  --bg-page: #FAFAF7;
  --bg-card: #FFFFFF;
  --bg-subtle: #F4F2EC;
  --border-soft: rgba(28,30,34,0.08);
  --border-medium: rgba(28,30,34,0.16);
  --text-1: #1F2024;
  --text-2: #4F4E4A;
  --text-3: #8A8983;
  --accent: #185FA5;
  --accent-dark: #0C447C;
  --accent-soft: #E6F1FB;
  --tag-PCH-bg: #E1F5EE; --tag-PCH-fg: #085041;
  --tag-QH-bg:  #E6F1FB; --tag-QH-fg:  #0C447C;
  --tag-AM-bg:  #FAEEDA; --tag-AM-fg:  #633806;
  --tag-CF-bg:  #FBEAF0; --tag-CF-fg:  #72243E;
  --tag-MS-bg:  #EEEDFE; --tag-MS-fg:  #3C3489;
  --highlight-bg: #FAEEDA;
  --highlight-fg: #854F0B;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --maxw: 940px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-serif: ui-serif, Georgia, "Times New Roman", "Songti SC", serif;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 76px; }
body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 15px;
  line-height: 1.7;
  color: var(--text-1);
  background: var(--bg-page);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
a { color: var(--accent); text-decoration: none; transition: color .15s; }
a:hover { color: var(--accent-dark); text-decoration: underline; }

/* ============ TOP NAV ============ */
.topnav {
  position: sticky; top: 0; z-index: 100;
  background: rgba(250,250,247,0.86);
  -webkit-backdrop-filter: saturate(180%) blur(10px);
  backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--border-soft);
}
.topnav-inner {
  max-width: var(--maxw); margin: 0 auto;
  padding: 12px 24px;
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
}
.brand {
  display: flex; align-items: center; gap: 10px;
  font-weight: 500; font-size: 14px; color: var(--text-1);
  letter-spacing: 0.2px;
}
.brand-mark {
  width: 28px; height: 28px;
  background: var(--accent); color: white;
  border-radius: 8px;
  display: grid; place-items: center;
  font-weight: 500; font-size: 14px;
}
.nav-links { display: flex; gap: 2px; font-size: 13px; }
.nav-links a {
  color: var(--text-2);
  padding: 6px 10px;
  border-radius: var(--radius-sm);
  transition: background .15s, color .15s;
}
.nav-links a:hover { background: var(--bg-subtle); color: var(--text-1); text-decoration: none; }
.lang-switch {
  display: flex; font-size: 12px;
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  overflow: hidden;
}
.lang-switch a { padding: 4px 10px; color: var(--text-3); }
.lang-switch a.active { background: var(--accent-soft); color: var(--accent); font-weight: 500; }

/* ============ CONTAINER ============ */
.container { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }

/* ============ HERO ============ */
.hero {
  display: grid; grid-template-columns: 200px 1fr;
  gap: 36px;
  padding: 48px 0 40px;
  align-items: stretch;
}
.bio { display: flex; flex-direction: column; }
.bio-foot { margin-top: auto; }
.photo-frame {
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
  padding: 8px;
}
.photo-frame img {
  width: 100%; height: auto; display: block; border-radius: 4px;
}
.photo-meta {
  text-align: center;
  margin-top: 10px;
  font-size: 11px;
  color: var(--text-3);
  letter-spacing: 0.4px;
}
.bio h1 {
  margin: 0;
  font-size: 32px; font-weight: 500;
  letter-spacing: -0.5px; line-height: 1.2;
}
.bio .cn-name {
  font-size: 18px; color: var(--text-2); font-weight: 400;
  margin-left: 10px;
}
.bio .title-line {
  margin: 8px 0 18px;
  color: var(--accent);
  font-size: 14px; font-weight: 500;
  letter-spacing: 0.2px;
}
.bio .tagline {
  margin: 0 0 24px;
  font-size: 15px; line-height: 1.7;
  color: var(--text-2);
  max-width: 580px;
}
.contact-chips { display: flex; gap: 8px; flex-wrap: wrap; }
.chip {
  display: inline-flex; align-items: center; gap: 6px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  color: var(--text-1);
  padding: 6px 13px;
  border-radius: 999px;
  font-size: 12.5px;
  transition: border-color .15s, background .15s, color .15s;
}
.chip:hover {
  border-color: var(--border-medium);
  background: var(--bg-subtle);
  text-decoration: none;
  color: var(--text-1);
}
.disc-pills {
  display: flex; flex-wrap: wrap; gap: 6px;
  margin: -10px 0 24px;
}
.disc {
  font-size: 11.5px; font-weight: 500;
  color: var(--text-2);
  background: var(--bg-subtle);
  border: 1px solid var(--border-soft);
  padding: 3px 11px;
  border-radius: 999px;
  letter-spacing: 0.3px;
}

/* ============ SECTIONS ============ */
.section { padding: 40px 0; border-top: 1px solid var(--border-soft); }
.section h2 {
  margin: 0 0 6px;
  font-size: 22px; font-weight: 500;
  letter-spacing: 0.1px;
}
.section-lead {
  margin: 0 0 18px;
  color: var(--text-2); font-size: 14px;
}
.subsection-title {
  margin: 20px 0 10px;
  font-size: 11px; font-weight: 500;
  color: var(--text-3);
  text-transform: uppercase;
  letter-spacing: 1px;
}
.subsection-title:first-of-type { margin-top: 12px; }

/* ============ RESEARCH GRID ============ */
.research-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(165px, 1fr));
  gap: 10px;
}
.research-card {
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius-md);
  padding: 14px 16px;
  transition: border-color .15s, background .15s;
}
.research-card:hover { border-color: var(--border-medium); }
.research-card[data-tag="PCH"] { border-left-color: var(--tag-PCH-fg); }
.research-card[data-tag="QH"]  { border-left-color: var(--tag-QH-fg); }
.research-card[data-tag="AM"]  { border-left-color: var(--tag-AM-fg); }
.research-card[data-tag="CF"]  { border-left-color: var(--tag-CF-fg); }
.research-card[data-tag="MS"]  { border-left-color: var(--tag-MS-fg); }
.research-card .tag-label {
  font-size: 11px; font-weight: 500;
  letter-spacing: 1.4px;
  margin-bottom: 6px;
}
.research-card[data-tag="PCH"] .tag-label { color: var(--tag-PCH-fg); }
.research-card[data-tag="QH"]  .tag-label { color: var(--tag-QH-fg); }
.research-card[data-tag="AM"]  .tag-label { color: var(--tag-AM-fg); }
.research-card[data-tag="CF"]  .tag-label { color: var(--tag-CF-fg); }
.research-card[data-tag="MS"]  .tag-label { color: var(--tag-MS-fg); }
.research-card .tag-full {
  font-size: 13px; color: var(--text-1); line-height: 1.55;
}

/* ============ TIMELINE ============ */
.timeline {
  position: relative;
  padding-left: 22px;
  margin: 0 0 32px;
}
.timeline::before {
  content: ""; position: absolute;
  left: 4px; top: 6px; bottom: 6px;
  width: 1px; background: var(--border-medium);
}
.timeline-item { position: relative; padding: 0 0 22px; }
.timeline-item:last-child { padding-bottom: 0; }
.timeline-item::before {
  content: ""; position: absolute;
  left: -22px; top: 8px;
  width: 9px; height: 9px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--bg-page);
}
.timeline-item.muted::before { background: var(--text-3); }
.timeline-year {
  font-size: 12px; color: var(--text-3);
  letter-spacing: 0.5px; margin-bottom: 2px;
  font-variant-numeric: tabular-nums;
}
.timeline-title {
  font-size: 15px; font-weight: 500;
  margin-bottom: 4px; color: var(--text-1);
}
.timeline-detail {
  font-size: 13.5px; color: var(--text-2); line-height: 1.6;
}

/* ============ HONORS ============ */
.honors-list {
  list-style: none; margin: 0; padding: 0;
  display: grid; grid-template-columns: 1fr; gap: 6px;
}
.honor-item {
  display: grid; grid-template-columns: 84px 1fr;
  gap: 16px;
  padding: 10px 14px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  font-size: 13.5px;
}
.honor-year {
  color: var(--text-3); font-size: 12px;
  font-variant-numeric: tabular-nums;
}

/* ============ PORTFOLIO ============ */
.portfolio-block {
  margin-top: 32px;
  padding: 18px 20px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
}
.portfolio-block h4 {
  margin: 0 0 12px;
  font-size: 11px; font-weight: 500;
  color: var(--text-3);
  text-transform: uppercase;
  letter-spacing: 1px;
}
.portfolio-group { margin-bottom: 14px; }
.portfolio-group:last-child { margin-bottom: 0; }
.portfolio-group .group-title {
  display: block;
  margin: 0 0 4px;
  font-size: 13px; font-weight: 500; font-style: italic;
  color: var(--text-2);
}
.portfolio-list {
  list-style: none; margin: 0; padding: 0;
}
.portfolio-list li {
  padding: 5px 0;
  font-size: 13.5px;
  color: var(--text-1);
  display: flex; gap: 10px; align-items: baseline;
}
.portfolio-list .port-date {
  font-size: 11px; color: var(--text-3);
  font-variant-numeric: tabular-nums;
  min-width: 64px;
}

/* ============ SERVICES ============ */
.services {
  margin-top: 18px;
  padding: 14px 18px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
  font-size: 13.5px; color: var(--text-2);
}
.services h4 {
  margin: 0 0 6px;
  font-size: 11px; font-weight: 500;
  color: var(--text-3);
  text-transform: uppercase;
  letter-spacing: 1px;
}

/* ============ PUBLICATION FILTERS ============ */
.pub-filters {
  display: flex; flex-wrap: wrap;
  gap: 5px;
  margin: 12px 0 16px;
}
.filter-btn {
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  color: var(--text-2);
  font-family: inherit;
  font-size: 12px; font-weight: 500;
  letter-spacing: 0.4px;
  padding: 4px 12px;
  border-radius: 999px;
  cursor: pointer;
  transition: all .15s;
}
.filter-btn:hover { border-color: var(--border-medium); color: var(--text-1); }
.filter-btn.active { background: var(--accent); border-color: var(--accent); color: white; }
.filter-btn[data-tag="PCH"].active { background: var(--tag-PCH-fg); border-color: var(--tag-PCH-fg); }
.filter-btn[data-tag="QH"].active  { background: var(--tag-QH-fg);  border-color: var(--tag-QH-fg); }
.filter-btn[data-tag="AM"].active  { background: var(--tag-AM-fg);  border-color: var(--tag-AM-fg); }
.filter-btn[data-tag="CF"].active  { background: var(--tag-CF-fg);  border-color: var(--tag-CF-fg); }
.filter-btn[data-tag="MS"].active  { background: var(--tag-MS-fg);  border-color: var(--tag-MS-fg); }

/* ============ PUBLICATION CARDS ============ */
.pub-list { display: flex; flex-direction: column; gap: 5px; }
.pub-card {
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
  padding: 14px 16px;
  display: grid;
  grid-template-columns: 78px minmax(0, 1fr) auto;
  gap: 14px;
  align-items: start;
  transition: border-color .15s;
}
.pub-card:hover { border-color: var(--border-medium); }
.pub-card.hidden { display: none; }
.pub-meta {
  display: flex; flex-direction: column; gap: 4px;
  align-items: center;
}
.tag {
  font-size: 10px; font-weight: 500;
  padding: 1px 7px;
  border-radius: 4px;
  letter-spacing: 0.6px;
}
.tag-PCH { background: var(--tag-PCH-bg); color: var(--tag-PCH-fg); }
.tag-QH  { background: var(--tag-QH-bg);  color: var(--tag-QH-fg); }
.tag-AM  { background: var(--tag-AM-bg);  color: var(--tag-AM-fg); }
.tag-CF  { background: var(--tag-CF-bg);  color: var(--tag-CF-fg); }
.tag-MS  { background: var(--tag-MS-bg);  color: var(--tag-MS-fg); }
.tag-extra { background: var(--bg-subtle); color: var(--text-2); }
.tag-highlight { background: var(--highlight-bg); color: var(--highlight-fg); }
.tag-cn { background: transparent; color: var(--text-3); border: 1px solid var(--border-soft); }
.pub-year {
  font-size: 11.5px; color: var(--text-3);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
  padding-top: 1px;
}
.pub-title {
  margin: 0 0 3px;
  font-size: 13.5px; font-weight: 500;
  line-height: 1.4;
  color: var(--text-1);
}
.pub-title a { color: var(--accent); }
.pub-title a:hover { color: var(--accent); }
.pub-authors {
  margin: 0 0 2px;
  font-size: 12px;
  color: var(--text-2);
  font-style: italic;
}
.pub-journal {
  margin: 0;
  font-size: 11.5px;
  color: var(--text-3);
}
.pub-journal em { font-style: italic; }
.pub-journal b { font-weight: 500; color: var(--text-2); }

/* ============ FOOTER ============ */
.site-footer {
  margin-top: 60px;
  padding: 28px 0 36px;
  border-top: 1px solid var(--border-soft);
  background: var(--bg-card);
}
.stats-row {
  display: flex; gap: 18px; flex-wrap: wrap;
  font-size: 12.5px;
  color: var(--text-2);
  align-items: center;
}
.stats-row .idx { color: var(--text-3); margin-right: 4px; }
.stats-row .stats-since { color: var(--text-3); }
.stats-row i { color: var(--text-3); font-style: normal; }
.copyright {
  margin-top: 12px;
  font-size: 12px;
  color: var(--text-3);
}

/* ============ BACK TO TOP ============ */
.back-to-top {
  position: fixed;
  right: 24px; bottom: 24px;
  width: 40px; height: 40px;
  border-radius: 50%;
  background: var(--bg-card);
  border: 1px solid var(--border-medium);
  color: var(--text-2);
  display: grid; place-items: center;
  font-size: 16px;
  text-decoration: none;
  opacity: 0;
  transform: translateY(8px);
  transition: opacity .2s, transform .2s, color .15s, border-color .15s;
  pointer-events: none;
}
.back-to-top.visible { opacity: 1; transform: translateY(0); pointer-events: auto; }
.back-to-top:hover { color: var(--accent); border-color: var(--accent); text-decoration: none; }

/* ============ RESPONSIVE ============ */
@media (max-width: 760px) {
  .topnav-inner { padding: 10px 16px; }
  .container { padding: 0 16px; }
  .hero {
    grid-template-columns: 1fr;
    gap: 22px;
    padding: 28px 0 24px;
    text-align: center;
  }
  .photo-frame { max-width: 160px; margin: 0 auto; }
  .bio h1 { font-size: 26px; }
  .bio .cn-name { display: block; margin-left: 0; margin-top: 4px; font-size: 16px; }
  .bio .tagline { margin-left: auto; margin-right: auto; }
  .disc-pills { justify-content: center; }
  .contact-chips { justify-content: center; }
  .section { padding: 32px 0; }
  .section h2 { font-size: 20px; }
  .research-grid { grid-template-columns: 1fr 1fr; }
  .honor-item { grid-template-columns: 68px 1fr; padding: 9px 12px; }
  .pub-card { grid-template-columns: 1fr; }
  .pub-year { padding-top: 0; }
  .pub-meta { flex-direction: row; flex-wrap: wrap; justify-content: flex-start; }
}
@media (max-width: 440px) {
  .research-grid { grid-template-columns: 1fr; }
  .nav-links { font-size: 12px; }
}
/* ============ SUBPAGE HEADINGS ============ */
.nav-links a.active { color: var(--text-1); background: var(--bg-subtle); }
.page-head { padding: 40px 0 0; }
.page-title {
  margin: 0;
  font-size: 24px; font-weight: 500;
  letter-spacing: 0.1px;
}

/* ============ HOME: SELECTED PUBLICATIONS ============ */
.sel-list {
  list-style: none; margin: 0; padding: 4px 16px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
}
.sel-list li {
  padding: 10px 0;
  border-bottom: 1px solid var(--border-soft);
  font-size: 13.5px;
}
.sel-list li:last-child { border-bottom: none; }
.sel-list .sel-title a { color: var(--accent); }
.sel-list .sel-journal {
  display: block; margin-top: 3px;
  font-size: 12px; font-style: italic; color: var(--text-3);
}
.view-all {
  display: inline-block; margin-top: 14px;
  padding: 6px 12px;
  font-size: 12.5px; font-weight: 500;
  color: var(--accent);
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
}
.view-all:hover { border-color: var(--border-medium); color: var(--accent-dark); text-decoration: none; }

/* ============ PORTFOLIO BLOG ============ */
.blog-list { display: flex; flex-direction: column; }
.blog-item {
  display: grid; grid-template-columns: 84px 1fr;
  gap: 16px;
  padding: 13px 0;
  border-top: 1px solid var(--border-soft);
}
.blog-item.hidden { display: none; }
.blog-date {
  font-size: 11.5px; color: var(--text-3);
  font-variant-numeric: tabular-nums;
  padding-top: 2px;
}
.blog-title { font-size: 14px; line-height: 1.5; }
.blog-title a { color: var(--accent); }
.blog-title a:hover { color: var(--accent); }
.blog-meta {
  margin-top: 5px;
  display: flex; align-items: center; gap: 8px; flex-wrap: wrap;
  font-size: 11.5px; color: var(--text-3);
}
.cat { font-size: 11px; padding: 1px 7px; border-radius: 4px; }
.cat-phy { background: var(--tag-PCH-bg); color: var(--tag-PCH-fg); }
.cat-ppl { background: var(--tag-QH-bg);  color: var(--tag-QH-fg); }
.cat-pop { background: var(--tag-AM-bg);  color: var(--tag-AM-fg); }

@media (max-width: 760px) {
  .blog-item { grid-template-columns: 68px 1fr; gap: 12px; }
}


/* ============ HOME: RESEARCH NOTE (boxed, centred) ============ */
.research-note {
  max-width: 660px;
  margin: 0 auto 26px;
  padding: 18px 24px;
  background: var(--bg-subtle);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
  text-align: center;
  color: var(--text-2);
  font-size: 14.5px;
  line-height: 1.75;
}
.research-note p { margin: 0; }

/* ============ EXPERIENCES: RESEARCH LIST (vertical) ============ */
.research-list { display: flex; flex-direction: column; }
.research-list .r-item {
  display: grid;
  grid-template-columns: 56px minmax(0, 1fr);
  gap: 16px;
  padding: 10px 0;
  border-top: 1px solid var(--border-soft);
}
.research-list .r-item:first-child { border-top: none; }
.research-list .r-label {
  font-size: 11.5px; font-weight: 500;
  letter-spacing: 1.2px;
  padding-top: 2px;
}
.research-list .r-text {
  font-size: 13.5px; color: var(--text-1); line-height: 1.6;
}
.research-list .r-item[data-tag="PCH"] .r-label { color: var(--tag-PCH-fg); }
.research-list .r-item[data-tag="QH"]  .r-label { color: var(--tag-QH-fg); }
.research-list .r-item[data-tag="AM"]  .r-label { color: var(--tag-AM-fg); }
.research-list .r-item[data-tag="CF"]  .r-label { color: var(--tag-CF-fg); }
.research-list .r-item[data-tag="MS"]  .r-label { color: var(--tag-MS-fg); }

/* ============ HOME: RESEARCH NOTE — VISUAL RELATION ============ */
.research-note .rn-top {
  margin: 0;
  font-size: 14.5px; font-weight: 500;
  color: var(--text-1);
}
.research-note .rn-arrow { margin: 12px 0; line-height: 0; color: var(--accent); }
.research-note .rn-fields {
  display: grid; grid-template-columns: 1fr auto 1fr;
  align-items: stretch; gap: 12px;
  margin: 16px 0 0;
}
.research-note .rn-field {
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
  padding: 10px 10px 12px;
}
.research-note .rn-field-name {
  font-size: 12.5px; font-weight: 500; line-height: 1.35;
}
.research-note .rn-field-pch .rn-field-name { color: var(--tag-PCH-fg); }
.research-note .rn-field-emhd .rn-field-name { color: var(--tag-QH-fg); }
.research-note .rn-op {
  align-self: center;
  font-size: 16px; line-height: 1; color: var(--accent);
}
.research-note .rn-fig {
  aspect-ratio: 1536 / 944;
  overflow: hidden;
  border-radius: 8px;
  margin-bottom: 10px;
  background: var(--bg-subtle);
}
.research-note .rn-fig img { display: block; width: 100%; height: auto; }
.research-note .rn-systems {
  display: grid; grid-template-columns: 1fr 1fr; gap: 12px;
}
.research-note .rn-system {
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
  padding: 10px 10px 12px;
}
.research-note .rn-system-name {
  font-size: 12.5px; font-weight: 500; color: var(--accent); line-height: 1.35;
}
@media (max-width: 760px) {
  .research-note .rn-fields { grid-template-columns: 1fr; gap: 10px; }
  .research-note .rn-systems { grid-template-columns: 1fr; }
  .research-note .rn-op { padding: 2px 0; }
}

/* ============ EXPERIENCES PAGE — COMPACT RHYTHM ============ */
.page-exp .page-head { padding: 26px 0 0; }
.page-exp .section { padding: 24px 0; }
.page-exp .section h2 { margin-bottom: 4px; }
.page-exp .section-lead { margin-bottom: 14px; }
.page-exp .subsection-title { margin: 14px 0 8px; }
.page-exp .timeline { margin: 0 0 20px; padding-left: 20px; }
.page-exp .timeline-item { padding: 0 0 14px; }
.page-exp .timeline-title { margin-bottom: 3px; }
.page-exp .timeline-detail { line-height: 1.55; }
.page-exp .research-list .r-item { padding: 8px 0; }
.page-exp .honors-list { gap: 4px; }
.page-exp .honor-item { padding: 7px 12px; }