/* ============================================================
   Bo Zhang Lab — style.css
   Clean minimal academic. EB Garamond + DM Sans.
   ============================================================ */

:root {
  --ink:       #1a1a1a;
  --ink-light: #555;
  --ink-faint: #999;
  --bg:        #fafaf8;
  --bg-off:    #f2f1ed;
  --accent:    #1d4e89;      /* deep academic blue */
  --accent-lt: #e8eef6;
  --border:    #dddbd5;
  --serif:     'EB Garamond', Georgia, serif;
  --sans:      'DM Sans', system-ui, sans-serif;
  --max-w:     900px;
  --nav-h:     60px;
}

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

html { font-size: 17px; scroll-behavior: smooth; }

body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--ink);
  line-height: 1.7;
  font-weight: 300;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ── NAV ── */
nav {
  position: sticky; top: 0; z-index: 100;
  height: var(--nav-h);
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  display: flex; align-items: center;
  padding: 0 2rem;
  gap: 2rem;
}

.nav-logo {
  font-family: var(--serif);
  font-size: 1.1rem;
  font-weight: 500;
  color: var(--ink);
  white-space: nowrap;
  letter-spacing: 0.01em;
  text-decoration: none;
}

nav ul {
  list-style: none;
  display: flex; gap: 0.25rem;
  margin-left: auto;
  flex-wrap: wrap;
}

nav ul a {
  font-size: 0.82rem;
  font-weight: 400;
  color: var(--ink-light);
  text-decoration: none;
  padding: 0.35rem 0.7rem;
  border-radius: 4px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  transition: color 0.15s, background 0.15s;
}

nav ul a:hover, nav ul a.active {
  color: var(--accent);
  background: var(--accent-lt);
}

.nav-toggle {
  display: none;
  background: none; border: none;
  font-size: 1.3rem; cursor: pointer;
  color: var(--ink); margin-left: auto;
}

/* ── HERO ── */
.hero {
  padding: 6rem 2rem 4rem;
  max-width: var(--max-w);
  margin: 0 auto;
}

.hero-label {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--ink-faint);
  margin-bottom: 1.2rem;
}

.hero h1 {
  font-family: var(--serif);
  font-size: clamp(2.2rem, 5vw, 3.5rem);
  font-weight: 400;
  line-height: 1.15;
  color: var(--ink);
  margin-bottom: 1.5rem;
}

.hero h1 em {
  font-style: italic;
  color: var(--ink-light);
}

.hero-sub {
  max-width: 620px;
  color: var(--ink-light);
  font-size: 1rem;
  line-height: 1.75;
  margin-bottom: 2rem;
}

.hero-links { display: flex; gap: 1rem; flex-wrap: wrap; }

.btn-primary {
  background: var(--accent);
  color: #fff;
  padding: 0.6rem 1.4rem;
  border-radius: 4px;
  font-size: 0.85rem;
  font-weight: 500;
  text-decoration: none;
  transition: opacity 0.15s;
}
.btn-primary:hover { opacity: 0.88; text-decoration: none; }

.btn-secondary {
  border: 1px solid var(--border);
  color: var(--ink);
  padding: 0.6rem 1.4rem;
  border-radius: 4px;
  font-size: 0.85rem;
  text-decoration: none;
  transition: border-color 0.15s;
}
.btn-secondary:hover { border-color: var(--accent); color: var(--accent); text-decoration: none; }

.hero-rule {
  margin-top: 4rem;
  border: none;
  border-top: 1px solid var(--border);
}

/* ── SECTIONS ── */
.section {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 4rem 2rem;
  border-bottom: 1px solid var(--border);
}
.section:last-of-type { border-bottom: none; }

.section-label {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--ink-faint);
  margin-bottom: 2rem;
}

/* ── PAGE HEADER ── */
.page-header {
  background: var(--bg-off);
  border-bottom: 1px solid var(--border);
  padding: 4rem 2rem 3rem;
}

.page-header-inner {
  max-width: var(--max-w);
  margin: 0 auto;
}

.page-header h1,
.page-header p,
.page-header .hero-label {
  display: block;
}

.page-header h1 {
  font-family: var(--serif);
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 400;
  margin: 0.5rem 0 0.75rem;
}

.page-header-sub {
  color: var(--ink-light);
  font-size: 0.95rem;
  display: block;
}

/* ── RESEARCH FIGURES ── */
.research-figure {
  margin: 1.25rem 0 0.5rem;
}

.research-figure img {
  width: 100%;
  display: block;
  margin: 0 auto;
  border-radius: 0;
  border: none;
}

.research-figure figcaption {
  text-align: center;
  font-size: 0.82rem;
  color: var(--ink-faint);
  margin-top: 0.6rem;
  font-style: italic;
}

/* ── RESEARCH DIRECTIONS GRID ── */
.directions-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 2rem;
}

.direction-card {
  padding: 1.75rem;
  background: var(--bg-off);
  border-radius: 6px;
  border: 1px solid var(--border);
}

.dir-num {
  font-family: var(--serif);
  font-size: 1.8rem;
  color: var(--border);
  display: block;
  margin-bottom: 0.75rem;
  line-height: 1;
}

.direction-card h3 {
  font-family: var(--serif);
  font-size: 1.05rem;
  font-weight: 500;
  margin-bottom: 0.6rem;
  line-height: 1.3;
}

.direction-card p {
  font-size: 0.88rem;
  color: var(--ink-light);
  line-height: 1.65;
}

/* ── PI SNAPSHOT ── */
.pi-snap {
  display: flex;
  gap: 4rem;
  align-items: flex-start;
  flex-wrap: wrap;
}

.pi-text { flex: 1; min-width: 260px; }
.pi-text h2 {
  font-family: var(--serif);
  font-size: 1.8rem;
  font-weight: 400;
  margin-bottom: 0.3rem;
}
.pi-title {
  color: var(--ink-light);
  font-size: 0.88rem;
  margin-bottom: 1rem;
}
.pi-text p { font-size: 0.92rem; color: var(--ink-light); margin-bottom: 0.5rem; }
.pi-text em { font-family: var(--serif); font-style: italic; }

.pi-right {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.5rem;
  width: 200px;
  flex-shrink: 0;
}

.pi-photo-home {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  object-fit: cover;
  object-position: center top;
  border: 1px solid var(--border);
  display: block;
  flex-shrink: 0;
}

.pi-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
  width: 100%;
}

.stat-item { text-align: center; }
.stat-num {
  display: block;
  font-family: var(--serif);
  font-size: 2.2rem;
  font-weight: 400;
  color: var(--accent);
  line-height: 1;
}
.stat-label {
  display: block;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--ink-faint);
  margin-top: 0.3rem;
}

@media (max-width: 640px) {
  .pi-right { width: 100%; }
  .pi-photo-home { width: 120px; height: 120px; }
}

/* ── NEWS SNAP ── */
.news-list { display: flex; flex-direction: column; gap: 1.25rem; }
.news-item { display: flex; gap: 1.5rem; align-items: baseline; }
.news-date {
  font-size: 0.8rem;
  color: var(--ink-faint);
  white-space: nowrap;
  min-width: 65px;
  font-variant-numeric: tabular-nums;
}
.news-text { font-size: 0.93rem; color: var(--ink-light); }
.news-text em { font-family: var(--serif); font-style: italic; }

/* ── PI FULL (people page) ── */
.pi-full {
  display: flex; gap: 2.5rem;
  align-items: flex-start;
  flex-wrap: wrap;
}

.pi-photo-placeholder {
  width: 180px; height: 180px;
  border-radius: 50%;
  background: var(--accent-lt);
  display: flex; align-items: center; justify-content: center;
  font-family: var(--serif);
  font-size: 1.5rem;
  color: var(--accent);
  flex-shrink: 0;
}

.pi-full-text { flex: 1; min-width: 260px; }
.pi-full-text h2 {
  font-family: var(--serif);
  font-size: 1.8rem;
  font-weight: 400;
  margin-bottom: 0.25rem;
}
.zh { font-size: 1.1rem; color: var(--ink-faint); margin-left: 0.5rem; }
.pi-full-text p { font-size: 0.93rem; color: var(--ink-light); margin-bottom: 0.75rem; }
.pi-full-text em { font-family: var(--serif); font-style: italic; }
.pi-contact { font-size: 0.88rem; color: var(--ink-faint); }

.pi-photo {
  width: 180px;
  height: 180px;
  border-radius: 50%;
  object-fit: cover;
  flex-shrink: 0;
  border: 1px solid var(--border);
}

.people-photo {
  width: 144px;
  height: 144px;
  min-width: 72px;
  border-radius: 50%;
  object-fit: cover;
  flex-shrink: 0;
  border: 1px solid var(--border);
}

/* ── PEOPLE LIST (with bio) ── */
.people-list { display: flex; flex-direction: column; gap: 0; }

.people-item {
  display: flex;
  gap: 1.75rem;
  padding: 1.75rem 0;
  border-bottom: 1px solid var(--border);
  align-items: flex-start;
}
.people-item:last-child { border-bottom: none; }

.people-photo-placeholder {
  width: 144px;
  height: 144px;
  border-radius: 50%;
  background: var(--accent-lt);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--serif);
  font-size: 1rem;
  color: var(--accent);
  flex-shrink: 0;
  border: 1px solid var(--border);
}

.people-body { flex: 1; }

.people-body h4 {
  font-size: 1rem;
  font-weight: 500;
  margin-bottom: 0.2rem;
}

.mascot-group-label {
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--ink-faint);
  margin-bottom: 0.75rem;
  margin-top: 1rem;
}

@media (max-width: 640px) {
  .people-item { flex-direction: column; gap: 0.75rem; }
}

/* ── MEMBERS GRID ── */
.members-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 1.5rem;
}

.member-card {
  text-align: center;
  padding: 1.5rem 1rem;
  border: 1px solid var(--border);
  border-radius: 6px;
}

.member-photo-placeholder {
  width: 72px; height: 72px;
  border-radius: 50%;
  background: var(--bg-off);
  display: flex; align-items: center; justify-content: center;
  font-size: 0.75rem;
  color: var(--ink-faint);
  margin: 0 auto 1rem;
  border: 1px solid var(--border);
}

.member-card h4 { font-size: 0.95rem; font-weight: 500; margin-bottom: 0.2rem; }
.member-role { font-size: 0.78rem; color: var(--ink-faint); margin-bottom: 0.3rem; }
.member-info { font-size: 0.83rem; color: var(--ink-light); }
.member-contact { font-size: 0.75rem; color: var(--ink-faint); margin-top: 0.2rem; }

/* ── ALUMNI ── */
.alumni-list { display: flex; flex-direction: column; gap: 0.75rem; }
.alumni-item { font-size: 0.9rem; color: var(--ink-light); }
.alumni-name { font-weight: 500; color: var(--ink); }

/* ── PUBLICATIONS ── */
.pub-list { display: flex; flex-direction: column; gap: 1.75rem; }

.pub-item {
  padding-bottom: 1.75rem;
  border-bottom: 1px solid var(--border);
}
.pub-item:last-child { border-bottom: none; padding-bottom: 0; }

.pub-meta {
  display: flex; gap: 1rem;
  align-items: center;
  margin-bottom: 0.4rem;
}

.pub-journal {
  font-size: 0.8rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--accent);
}

.pub-year {
  font-size: 0.8rem;
  color: var(--ink-faint);
}

.pub-title {
  font-family: var(--serif);
  font-size: 1rem;
  line-height: 1.5;
  margin-bottom: 0.5rem;
}

.pub-links { display: flex; gap: 0.75rem; }
.pub-link {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--ink-faint);
  border: 1px solid var(--border);
  padding: 0.2rem 0.6rem;
  border-radius: 3px;
  text-decoration: none;
  transition: color 0.15s, border-color 0.15s;
}
.pub-link:hover { color: var(--accent); border-color: var(--accent); text-decoration: none; }

.pub-badge {
  font-size: 0.72rem;
  background: #fff3cd;
  color: #856404;
  border: 1px solid #ffe69c;
  padding: 0.15rem 0.5rem;
  border-radius: 3px;
}

.highlight-pub {
  border-left: 3px solid var(--accent);
  padding-left: 1rem;
}

.pub-highlight {
  font-size: 0.78rem;
  color: var(--ink-faint);
  margin-top: 0.4rem;
  font-style: italic;
}

.pub-filter-bar {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 1.25rem 2rem;
  display: flex;
  gap: 0.5rem;
  align-items: center;
  flex-wrap: wrap;
  border-bottom: 1px solid var(--border);
}

.filter-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--ink-faint);
  margin-right: 0.5rem;
}

.pub-filter-bar a {
  font-size: 0.8rem;
  color: var(--ink-light);
  border: 1px solid var(--border);
  padding: 0.2rem 0.65rem;
  border-radius: 3px;
  text-decoration: none;
  transition: color 0.15s, border-color 0.15s;
}

.pub-filter-bar a:hover {
  color: var(--accent);
  border-color: var(--accent);
  text-decoration: none;
}

/* ── RESEARCH PAGE ── */
.research-overview {
  max-width: 680px;
}
.research-overview p {
  font-family: var(--serif);
  font-size: 1.1rem;
  line-height: 1.75;
  color: var(--ink-light);
}

.research-block {
  display: flex; gap: 2rem;
  padding: 2.5rem 0;
  border-bottom: 1px solid var(--border);
}
.research-block:last-child { border-bottom: none; }

.research-block-num {
  font-family: var(--serif);
  font-size: 2.5rem;
  color: var(--border);
  flex-shrink: 0;
  width: 3rem;
  line-height: 1;
  padding-top: 0.2rem;
}

.research-block-body h3 {
  font-family: var(--serif);
  font-size: 1.2rem;
  font-weight: 500;
  margin-bottom: 0.75rem;
}

.research-block-body p {
  font-size: 0.93rem;
  color: var(--ink-light);
  line-height: 1.75;
  margin-bottom: 1rem;
}

.research-tags { display: flex; gap: 0.5rem; flex-wrap: wrap; }
.research-tags span {
  font-size: 0.75rem;
  background: var(--accent-lt);
  color: var(--accent);
  padding: 0.2rem 0.6rem;
  border-radius: 3px;
}

.funding-list { display: flex; flex-direction: column; gap: 0.75rem; }
.funding-item { font-size: 0.9rem; color: var(--ink-light); padding-left: 1rem; border-left: 2px solid var(--border); }

/* ── NEWS FULL ── */
.news-full-list { display: flex; flex-direction: column; }

.news-full-item {
  display: flex; gap: 2rem;
  padding: 1.75rem 0;
  border-bottom: 1px solid var(--border);
}
.news-full-item:last-child { border-bottom: none; }

.news-full-date {
  min-width: 130px;
  font-size: 0.82rem;
  color: var(--ink-faint);
  padding-top: 0.2rem;
}

.news-full-content { flex: 1; }

.news-tag {
  display: inline-block;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  background: var(--accent-lt);
  color: var(--accent);
  padding: 0.15rem 0.5rem;
  border-radius: 3px;
  margin-bottom: 0.5rem;
}

.news-full-content p {
  font-size: 0.93rem;
  color: var(--ink-light);
}

.joinus-hero {
  width: 100%;
  padding: 2.5rem 2rem 0;
  box-sizing: border-box;
}

.joinus-hero img {
  width: 100%;
  max-width: var(--max-w);
  border-radius: 0;
  border: none;
  display: block;
  margin: 0 auto;
}

/* ── JOIN US ── */
.join-block {
  padding: 2rem 0;
  border-bottom: 1px solid var(--border);
}
.join-block:last-child { border-bottom: none; }
.join-block h3 {
  font-family: var(--serif);
  font-size: 1.15rem;
  font-weight: 500;
  margin-bottom: 0.6rem;
}
.join-block p { font-size: 0.93rem; color: var(--ink-light); line-height: 1.75; }

.contact-block { display: flex; flex-direction: column; gap: 1.5rem; }
.contact-item { display: flex; gap: 1.5rem; font-size: 0.93rem; }
.contact-label {
  min-width: 80px;
  font-weight: 500;
  color: var(--ink-faint);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding-top: 0.1rem;
}
.contact-item span:last-child { color: var(--ink-light); line-height: 1.75; }

.funding-group { margin-bottom: 3rem; }

.funding-group-title {
  font-family: var(--serif);
  font-size: 1.1rem;
  font-weight: 500;
  margin-bottom: 0.3rem;
}

.funding-group-note {
  font-size: 0.83rem;
  color: var(--ink-faint);
  margin-bottom: 1.25rem;
  font-style: italic;
}

.funding-table { display: flex; flex-direction: column; }

.funding-row {
  display: flex;
  gap: 2rem;
  padding: 1rem 0;
  border-bottom: 1px solid var(--border);
  align-items: baseline;
}
.funding-row:last-child { border-bottom: none; }

.funding-year {
  min-width: 44px;
  font-size: 0.82rem;
  color: var(--ink-faint);
  font-variant-numeric: tabular-nums;
  padding-top: 0.1rem;
}

.funding-body { flex: 1; }

.funding-title {
  font-size: 0.93rem;
  color: var(--ink);
  margin-bottom: 0.25rem;
  line-height: 1.55;
}

.funding-source {
  font-size: 0.8rem;
  color: var(--ink-faint);
}

.funding-role {
  color: var(--accent);
}

.news-photo {
  margin: 0.75rem 0 0;
}

.news-photo img {
  width: 100%;
  max-width: 560px;
  display: block;
  border: none;
  border-radius: 0;
}

/* ── FOOTER ── */
footer {
  background: var(--bg-off);
  border-top: 1px solid var(--border);
  padding: 3rem 2rem 2rem;
}

.footer-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  display: flex; gap: 4rem;
  flex-wrap: wrap;
  font-size: 0.85rem;
  color: var(--ink-light);
  line-height: 1.8;
  margin-bottom: 2rem;
}

.footer-copy {
  max-width: var(--max-w);
  margin: 0 auto;
  font-size: 0.75rem;
  color: var(--ink-faint);
  border-top: 1px solid var(--border);
  padding-top: 1rem;
}

/* ── RESPONSIVE ── */
@media (max-width: 640px) {
  nav ul { display: none; flex-direction: column; position: absolute; top: var(--nav-h); left: 0; right: 0; background: var(--bg); border-bottom: 1px solid var(--border); padding: 1rem 2rem; }
  nav ul.open { display: flex; }
  .nav-toggle { display: block; }
  .pi-snap { flex-direction: column; gap: 2rem; }
  .pi-stats { grid-template-columns: repeat(4, 1fr); }
  .research-block { flex-direction: column; gap: 0.5rem; }
  .research-block-num { font-size: 1.5rem; width: auto; }
  .news-full-item { flex-direction: column; gap: 0.5rem; }
  .contact-item { flex-direction: column; gap: 0.25rem; }
}