/* ─── Reset & Base ─── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #0d0d0f;
  --bg-surface: #141417;
  --bg-card: #1a1a1f;
  --border: rgba(255,255,255,0.08);
  --border-hover: rgba(255,255,255,0.16);
  --accent: #7c6ef7;
  --accent-soft: rgba(124,110,247,0.12);
  --text-primary: #f0eff5;
  --text-secondary: #9490a8;
  --text-muted: #5c5870;
  --font: 'Inter', system-ui, sans-serif;
  --mono: 'JetBrains Mono', monospace;
  --radius: 10px;
  --max-w: 860px;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text-primary);
  font-size: 16px;
  line-height: 1.7;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
em { font-style: italic; color: var(--text-primary); }
strong { font-weight: 600; color: var(--text-primary); }

/* ─── Nav ─── */
header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(13,13,15,0.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.nav-container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 2rem;
  height: 60px;
  display: flex;
  align-items: center;
  gap: 2rem;
}

.nav-logo {
  font-family: var(--mono);
  font-size: 14px;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: 0.05em;
  text-decoration: none;
  flex-shrink: 0;
}

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

.nav-links a {
  font-size: 14px;
  font-weight: 400;
  color: var(--text-secondary);
  padding: 0.35rem 0.75rem;
  border-radius: 6px;
  transition: color 0.15s, background 0.15s;
  text-decoration: none;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--text-primary);
  background: var(--accent-soft);
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text-secondary);
  font-size: 20px;
  cursor: pointer;
  margin-left: auto;
}

/* ─── Layout ─── */
main { flex: 1; }

.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 2rem;
}

.section {
  padding: 4rem 0;
  border-top: 1px solid var(--border);
}

.section:first-of-type { border-top: none; }

.section-title {
  font-size: 1.25rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.section-subtitle {
  font-size: 0.95rem;
  color: var(--text-secondary);
  margin-bottom: 2.5rem;
}

/* ─── Hero ─── */
.hero {
  padding: 5rem 0 3rem;
  max-width: var(--max-w);
  margin: 0 auto;
  padding-left: 2rem;
  padding-right: 2rem;
}

.hero-content {
  display: flex;
  gap: 3rem;
  align-items: flex-start;
}

.hero-text { flex: 1; }

.hero-tag {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--accent);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 1rem;
}

h1 {
  font-size: clamp(2rem, 5vw, 2.75rem);
  font-weight: 600;
  line-height: 1.2;
  margin-bottom: 1.25rem;
  color: var(--text-primary);
}

h1 .muted { color: var(--text-muted); font-weight: 300; }

.hero-bio {
  font-size: 1.05rem;
  color: var(--text-secondary);
  margin-bottom: 2rem;
  max-width: 540px;
}

.hero-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1.25rem;
}

.pronouns {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text-muted);
}

/* ─── Buttons ─── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 14px;
  font-weight: 500;
  padding: 0.5rem 1.1rem;
  border-radius: 8px;
  text-decoration: none;
  transition: all 0.15s;
  cursor: pointer;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
  border: 1px solid var(--accent);
}
.btn-primary:hover { opacity: 0.88; text-decoration: none; }

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid var(--border-hover);
}
.btn-ghost:hover {
  color: var(--text-primary);
  border-color: var(--border-hover);
  background: var(--bg-card);
  text-decoration: none;
}

/* ─── Photo ─── */
.hero-photo { flex-shrink: 0; }

.photo-frame {
  width: 160px;
  height: 160px;
  border-radius: 50%;
  border: 2px solid var(--border-hover);
  overflow: hidden;
  background: var(--bg-card);
}

.photo-frame img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.photo-placeholder::after {
  content: 'ZH';
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 100%;
  font-family: var(--mono);
  font-size: 1.5rem;
  color: var(--accent);
  background: var(--accent-soft);
}

/* ─── Cards ─── */
.two-col {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1rem;
}

.three-col {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.25rem;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  transition: border-color 0.15s;
}

.card:hover { border-color: var(--border-hover); }

.card-icon {
  font-size: 1.25rem;
  margin-bottom: 0.75rem;
}

.card h3 {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

/* ─── Interest items ─── */
.interest-item {
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.interest-num {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--accent);
  display: block;
  margin-bottom: 0.5rem;
}

.interest-item h4 {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.interest-item p {
  font-size: 0.88rem;
  color: var(--text-secondary);
}

/* ─── Timeline ─── */
.timeline {
  display: flex;
  flex-direction: column;
  gap: 0;
  border-left: 1px solid var(--border);
  margin-left: 3rem;
}

.timeline-item {
  display: flex;
  gap: 2rem;
  padding: 1.5rem 0 1.5rem 2rem;
  position: relative;
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: -5px;
  top: 1.9rem;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--bg);
}

.timeline-year {
  font-family: var(--mono);
  font-size: 13px;
  color: var(--accent);
  font-weight: 500;
  min-width: 40px;
  padding-top: 2px;
}

.timeline-content h4 {
  font-size: 1rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.25rem;
}

.timeline-content p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 0.4rem;
}

.tag {
  display: inline-block;
  font-size: 0.8rem;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
  font-family: var(--mono);
}

/* ─── Publications Page ─── */
.pub-list { display: flex; flex-direction: column; gap: 1px; }

.pub-item {
  display: flex;
  gap: 1.5rem;
  padding: 1.5rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 0.75rem;
  transition: border-color 0.15s, background 0.15s;
}

.pub-item:hover {
  border-color: var(--border-hover);
  background: var(--bg-card);
}

.pub-year {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--accent);
  min-width: 40px;
  padding-top: 3px;
}

.pub-body h4 {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.25rem;
}

.pub-body .authors {
  font-size: 0.88rem;
  color: var(--text-secondary);
  margin-bottom: 0.25rem;
}

.pub-body .venue {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-style: italic;
  margin-bottom: 0.5rem;
}

.pub-links { display: flex; gap: 0.5rem; flex-wrap: wrap; }

.pub-link {
  font-size: 0.78rem;
  font-family: var(--mono);
  color: var(--accent);
  border: 1px solid var(--accent-soft);
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  text-decoration: none;
}
.pub-link:hover { background: var(--accent-soft); text-decoration: none; }

/* ─── Teaching Page ─── */
.teaching-grid {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.course-item {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
  transition: border-color 0.15s;
}

.course-item:hover { border-color: var(--border-hover); }

.course-left h4 {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.25rem;
}

.course-left p {
  font-size: 0.88rem;
  color: var(--text-secondary);
}

.course-right {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text-muted);
  white-space: nowrap;
}

.role-badge {
  display: inline-block;
  font-size: 0.75rem;
  font-family: var(--mono);
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  background: var(--accent-soft);
  color: var(--accent);
  margin-top: 0.4rem;
}

/* ─── CV Page ─── */
.cv-section { margin-bottom: 3rem; }

.cv-section h2 {
  font-size: 0.75rem;
  font-family: var(--mono);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 1.25rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border);
}

.cv-item {
  display: flex;
  gap: 2rem;
  margin-bottom: 1.5rem;
}

.cv-year {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text-muted);
  width: 130px;
  min-width: 130px;
  padding-top: 3px;
}

.cv-content h4 {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.2rem;
}

.cv-content p {
  font-size: 0.88rem;
  color: var(--text-secondary);
}

/* ─── Page header ─── */
.page-header {
  padding: 4rem 0 2.5rem;
}

.page-header h1 {
  font-size: 2rem;
  margin-bottom: 0.5rem;
}

.page-header p {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

/* ─── Footer ─── */
footer {
  border-top: 1px solid var(--border);
  padding: 1.5rem 0;
  margin-top: auto;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.footer-inner a {
  color: var(--text-muted);
  text-decoration: none;
}

.footer-inner a:hover { color: var(--text-secondary); }

/* ─── Responsive ─── */
@media (max-width: 640px) {
  .hero-content { flex-direction: column-reverse; gap: 2rem; }
  .hero-photo { align-self: center; }
  .photo-frame { width: 120px; height: 120px; }
  .nav-links { display: none; flex-direction: column; position: absolute; top: 60px; left: 0; right: 0; background: var(--bg-surface); border-bottom: 1px solid var(--border); padding: 1rem 2rem; }
  .nav-links.open { display: flex; }
  .nav-toggle { display: block; }
  .timeline { margin-left: 0; }
  .cv-item { flex-direction: column; gap: 0.25rem; }
  .course-item { flex-direction: column; }
  .footer-inner { flex-direction: column; gap: 0.5rem; text-align: center; }
  .section { padding: 2.5rem 0; }
}