:root {
  --fg: #1a1a1a;
  --muted: #6b7280;
  --subtle: #9ca3af;
  --accent: #660874;
  --accent-soft: #f4ecf6;
  --bg: #ffffff;
  --bg-alt: #fafafa;
  --border: #e5e7eb;
  --topbar-bg: rgba(255,255,255,0.92);
  --radius: 6px;
  --max: 900px;
  --font-sans: ui-sans-serif, system-ui, -apple-system, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-serif: "Source Serif Pro", "Noto Serif SC", ui-serif, Georgia, serif;
}

:root[data-theme="dark"] {
  --fg: #e5e7eb;
  --muted: #9ca3af;
  --subtle: #6b7280;
  --accent: #c084d8;
  --accent-soft: #2a1530;
  --bg: #0f0f11;
  --bg-alt: #1a1a1e;
  --border: #2a2a30;
  --topbar-bg: rgba(15,15,17,0.92);
}

:root[data-theme="dark"] img,
:root[data-theme="dark"] .avatar {
  filter: brightness(0.92);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 70px; }

body {
  margin: 0;
  font-family: var(--font-sans);
  color: var(--fg);
  background: var(--bg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  font-size: 15.5px;
}

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

h1, h2, h3 { font-weight: 600; letter-spacing: -0.01em; }
h1 { font-size: 1.9rem; margin: 0 0 0.4rem; }
h2 { font-size: 1.35rem; margin: 0 0 1rem; padding-bottom: 0.4rem; border-bottom: 1px solid var(--border); }
h3 { font-size: 1rem; margin: 0 0 0.7rem; color: var(--fg); }

/* ===== Topbar ===== */
.topbar {
  position: sticky; top: 0; z-index: 50;
  background: var(--topbar-bg);
  backdrop-filter: saturate(180%) blur(8px);
  border-bottom: 1px solid var(--border);
}
.topbar-inner {
  max-width: var(--max); margin: 0 auto;
  padding: 0.7rem 1.25rem;
  display: flex; align-items: center; gap: 1rem;
}
.brand {
  font-weight: 600; color: var(--fg);
  font-size: 1rem;
}
.nav {
  display: flex; gap: 1rem; margin-left: auto;
  font-size: 0.92rem;
  flex-wrap: wrap;
}
.nav a { color: var(--muted); }
.nav a:hover, .nav a.active { color: var(--accent); text-decoration: none; }
.lang-toggle {
  display: flex; gap: 0.25rem; margin-left: 0.75rem;
  border: 1px solid var(--border); border-radius: var(--radius);
  padding: 2px;
}
.lang-toggle button {
  background: none; border: 0; padding: 0.2rem 0.55rem;
  font-size: 0.85rem; cursor: pointer; color: var(--muted);
  border-radius: 4px; font-family: inherit;
}
.lang-toggle button.active { background: var(--accent); color: #fff; }

/* ===== Theme toggle ===== */
.theme-toggle {
  background: none; border: 1px solid var(--border);
  border-radius: var(--radius);
  width: 32px; height: 32px;
  display: inline-flex; align-items: center; justify-content: center;
  cursor: pointer; color: var(--muted);
  padding: 0;
  transition: color 0.15s, border-color 0.15s;
}
.theme-toggle:hover { color: var(--accent); border-color: var(--accent); }
.theme-toggle .icon-moon { display: none; }
:root[data-theme="dark"] .theme-toggle .icon-sun { display: none; }
:root[data-theme="dark"] .theme-toggle .icon-moon { display: inline-block; }

/* ===== Main ===== */
main {
  max-width: var(--max);
  margin: 0 auto;
  padding: 2.5rem 1.25rem 4rem;
}

section { margin-top: 3rem; }
section:first-of-type { margin-top: 0; }

/* ===== Hero ===== */
.hero {
  display: flex; gap: 2rem; align-items: flex-start;
  padding-bottom: 2rem; border-bottom: 1px solid var(--border);
}
.avatar {
  width: 180px; height: 240px;
  object-fit: cover; border-radius: var(--radius);
  background: var(--bg-alt);
  flex-shrink: 0;
}
.hero-body { flex: 1; min-width: 0; }
.subtitle { color: var(--muted); margin-bottom: 1rem; font-size: 0.98rem; }
.subtitle .sep { margin: 0 0.5rem; color: var(--subtle); }
.bio { margin: 0.75rem 0; }
.meta { margin: 0.75rem 0; font-size: 0.95rem; }
.tags {
  display: flex; flex-wrap: wrap; gap: 0.4rem;
  margin-top: 0.9rem;
}
.tag {
  font-size: 0.82rem; padding: 0.18rem 0.6rem;
  background: var(--accent-soft); color: var(--accent);
  border-radius: 999px;
}

/* ===== Two-column ===== */
.two-col {
  display: grid; grid-template-columns: 1fr 1fr;
  gap: 2rem;
}
.timeline { list-style: none; padding: 0; margin: 0; }
.timeline li {
  padding: 0.4rem 0;
  display: grid; grid-template-columns: 140px 1fr; gap: 0.75rem;
  font-size: 0.94rem;
}
.timeline .period { color: var(--muted); font-variant-numeric: tabular-nums; }

/* ===== News ===== */
.news-card {
  border: 1px solid var(--border); border-left: 3px solid var(--accent);
  border-radius: var(--radius); padding: 1.25rem 1.5rem;
  background: var(--bg-alt);
  position: relative;
}
.news-badge {
  position: absolute; top: 1rem; right: 1.25rem;
  background: var(--accent); color: #fff;
  font-size: 0.75rem; padding: 0.15rem 0.5rem; border-radius: 4px;
  letter-spacing: 0.03em;
}
.news-card h3 { margin-top: 0; }
.news-card ul { padding-left: 1.2rem; margin: 0.5rem 0; }
.news-card li { margin-bottom: 0.35rem; }
.news-card li.recruit-subitem {
  margin-left: 1.75rem;
  color: var(--muted);
}
.news-card .cta {
  margin: 0.75rem 0 0; font-size: 0.92rem; color: var(--muted);
}

/* ===== Research areas ===== */
.research-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem;
}
.research-card {
  border: 1px solid var(--border); border-radius: var(--radius);
  padding: 1rem 1.1rem; background: var(--bg);
}
.research-card h3 { color: var(--accent); margin-bottom: 0.4rem; }
.research-card p { margin: 0; font-size: 0.92rem; color: var(--muted); }

/* ===== Publications ===== */
.pub-list { list-style: none; padding: 0; margin: 0; counter-reset: pub; }
.pub-list li {
  counter-increment: pub;
  display: grid; grid-template-columns: 240px 1fr; gap: 1.4rem;
  padding: 1.4rem 0; border-top: 1px solid var(--border);
}
.pub-list li:first-child { border-top: 0; padding-top: 0; }
.pub-list li::before { display: none; }
.pub-teaser {
  width: 240px; height: 150px;
  background: var(--bg-alt); border: 1px solid var(--border);
  border-radius: 4px;
  display: flex; align-items: center; justify-content: center;
  color: var(--subtle); font-size: 0.8rem;
  overflow: hidden;
}
.pub-teaser img { width: 100%; height: 100%; object-fit: cover; }
.pub-body { display: flex; flex-direction: column; min-width: 0; }
.pub-body .pub-title {
  font-weight: 600; color: var(--fg);
  font-size: 1rem; line-height: 1.45;
  margin-bottom: 0.25rem;
}
.pub-body .pub-authors { color: var(--fg); font-size: 0.9rem; margin-bottom: 0.2rem; }
.pub-body .pub-authors b { color: var(--fg); }
.pub-body .pub-venue { color: var(--muted); font-size: 0.9rem; font-style: italic; }
.pub-body .pub-links { margin-top: 0.4rem; font-size: 0.85rem; }
.pub-body .pub-links a {
  margin-right: 0.5rem; padding: 0.1rem 0.5rem;
  border: 1px solid var(--border); border-radius: 4px;
  color: var(--muted);
}
.pub-body .pub-links a:hover {
  color: var(--accent); border-color: var(--accent); text-decoration: none;
}
.pub-abstract {
  margin-top: 0.75rem;
  color: var(--fg);
  font-size: 0.9rem;
  line-height: 1.58;
}
/* ===== Plain lists ===== */
.plain { list-style: none; padding: 0; margin: 0; }
.plain li {
  padding: 0.55rem 0;
  border-top: 1px solid var(--border);
  font-size: 0.95rem;
}
.plain li:first-child { border-top: 0; }

.proj-list { list-style: none; padding: 0; margin: 0; }
.proj-list li {
  display: grid; grid-template-columns: 1fr 130px; gap: 1rem;
  padding: 0.6rem 0;
  border-top: 1px solid var(--border);
  font-size: 0.95rem;
}
.proj-list li:first-child { border-top: 0; }
.proj-list .period {
  color: var(--muted); font-variant-numeric: tabular-nums;
  text-align: right; font-size: 0.88rem;
}

/* ===== Patents ===== */
.patent-list {
  list-style: none; padding: 0; margin: 0;
  counter-reset: pat;
}
.patent-list li {
  counter-increment: pat;
  padding: 0.65rem 0 0.65rem 2.2rem;
  border-top: 1px solid var(--border);
  position: relative;
  font-size: 0.92rem;
}
.patent-list li:first-child { border-top: 0; }
.patent-list li::before {
  content: counter(pat) ".";
  position: absolute; left: 0; top: 0.65rem;
  color: var(--subtle); font-variant-numeric: tabular-nums;
  width: 2rem; text-align: right;
}
.patent-title { font-weight: 500; }
.patent-meta { color: var(--muted); font-size: 0.85rem; margin-top: 0.1rem; }

/* ===== Students ===== */
.student-group {
  margin-bottom: 1.2rem;
}
.student-group h4 {
  margin: 0 0 0.5rem;
  font-size: 0.92rem; font-weight: 600;
  color: var(--accent);
}
.student-group ul { list-style: none; padding: 0; margin: 0; }
.student-group li {
  display: grid; grid-template-columns: 90px 1fr; gap: 0.75rem;
  padding: 0.25rem 0;
  font-size: 0.93rem;
}
.student-group .year {
  color: var(--muted); font-variant-numeric: tabular-nums;
}

/* ===== Contact ===== */
.contact li {
  display: grid; grid-template-columns: 80px 1fr; gap: 0.5rem;
  border-top: 1px solid var(--border);
  padding: 0.6rem 0;
}
.contact li .label { color: var(--muted); }
.contact li .label::after { content: "："; }

/* ===== Footer ===== */
footer {
  border-top: 1px solid var(--border);
  padding: 1.5rem 1.25rem;
  margin-top: 3rem;
  color: var(--muted); font-size: 0.87rem;
}
.footer-inner {
  max-width: var(--max); margin: 0 auto;
  display: flex; justify-content: center; gap: 0.5rem; flex-wrap: wrap;
}
.footer-inner .sep { color: var(--subtle); }

/* ===== Responsive ===== */
@media (max-width: 680px) {
  .topbar-inner { flex-wrap: wrap; padding: 0.6rem 1rem; }
  .nav { order: 3; width: 100%; justify-content: flex-start; gap: 0.75rem; margin-left: 0; }
  .theme-toggle { order: 2; }
  .lang-toggle { margin-left: auto; }
  main { padding: 1.75rem 1rem 3rem; }
  .hero { flex-direction: column; gap: 1.25rem; align-items: center; text-align: center; }
  .avatar { width: 150px; height: 200px; }
  .hero .tags { justify-content: center; }
  .two-col { grid-template-columns: 1fr; gap: 1.2rem; }
  .research-grid { grid-template-columns: 1fr; }
  .pub-list li { grid-template-columns: 1fr; }
  .pub-teaser { width: 100%; height: 180px; }
  .proj-list li { grid-template-columns: 1fr; }
  .proj-list .period { text-align: left; }
  .timeline li { grid-template-columns: 110px 1fr; }
  .contact li { grid-template-columns: 70px 1fr; }
}