:root {
  --color-bg: #ffffff;
  --color-text: #1e293b;
  --color-text-secondary: #64748b;
  --color-accent: #4b83c7;
  --color-accent-hover: #3d6fad;
  --color-accent-light: #e8eef6;
  --color-border: #e2e8f0;
  --color-tag-bg: #eef2f7;
  --color-tag-text: #3d6fad;
  --color-warm: #b47a3e;
  --color-warm-light: #fdf4e8;
  --color-warm-border: #f0dfc8;
  --color-section-alt: #f8fafc;
  --color-card-shadow: rgba(74, 114, 168, 0.06);
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --max-width: 860px;
  --radius: 10px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
}

body {
  font-family: var(--font-body);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.75;
  font-size: 16.5px;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color 0.2s;
}

a:hover {
  color: var(--color-accent-hover);
}

/* Navigation */
nav {
  position: sticky;
  top: 0;
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--color-border);
  z-index: 100;
}

nav .nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

nav .nav-name {
  font-weight: 800;
  font-size: 18px;
  color: var(--color-text);
  letter-spacing: -0.02em;
}

nav .nav-links {
  display: flex;
  gap: 28px;
  list-style: none;
}

nav .nav-links a {
  color: var(--color-text-secondary);
  font-size: 15px;
  font-weight: 500;
  transition: color 0.2s;
  position: relative;
}

nav .nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--color-accent);
  border-radius: 1px;
  transition: width 0.25s ease;
}

nav .nav-links a:hover {
  color: var(--color-accent);
}

nav .nav-links a:hover::after {
  width: 100%;
}

/* Main content */
main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 28px;
}

/* Hero / Bio section */
.hero {
  padding: 64px 0 48px;
}

.hero h1 {
  font-size: 40px;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: 8px;
  color: var(--color-text);
  background: linear-gradient(135deg, var(--color-text) 0%, #334155 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.name-cn {
  font-size: 24px;
  font-weight: 500;
  letter-spacing: 0;
}

.hero .affiliation {
  font-size: 17px;
  color: var(--color-text-secondary);
  margin-bottom: 4px;
  font-weight: 500;
}

.hero .contact {
  font-size: 15.5px;
  color: var(--color-text-secondary);
  margin-bottom: 24px;
}

.hero .contact a {
  color: var(--color-text-secondary);
  border-bottom: 1px dashed var(--color-border);
  transition: all 0.2s;
}

.hero .contact a:hover {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

.hero .bio {
  font-size: 16.5px;
  line-height: 1.85;
  color: var(--color-text);
  max-width: 760px;
}

.hero .bio p {
  margin-bottom: 10px;
}

.hero .bio p:last-child {
  margin-bottom: 0;
}

.hero .external-links {
  margin-top: 22px;
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.hero .external-links a {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 14.5px;
  font-weight: 600;
  color: var(--color-accent);
  padding: 8px 18px;
  border: 1.5px solid var(--color-accent-light);
  border-radius: 8px;
  background: var(--color-tag-bg);
  transition: all 0.2s;
}

.hero .external-links a:hover {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.2);
}

.hiring-note {
  margin-top: 28px;
  padding: 18px 22px;
  background: var(--color-warm-light);
  border-left: 4px solid var(--color-warm);
  border-radius: 0 var(--radius) var(--radius) 0;
  font-size: 15.5px;
  line-height: 1.75;
  color: var(--color-text);
}

.hiring-note strong {
  color: var(--color-text);
}

/* Section styling */
section {
  padding: 48px 0;
}

section:nth-child(odd) {
  position: relative;
}

.section-divider {
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--color-border), transparent);
  margin: 0;
  border: none;
}

section h2 {
  font-size: 24px;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 28px;
  color: var(--color-text);
  display: flex;
  align-items: center;
  gap: 10px;
}

section h2::before {
  content: '';
  display: inline-block;
  width: 4px;
  height: 24px;
  background: var(--color-accent);
  border-radius: 2px;
}

/* Work experience */
.experience-item {
  font-size: 16px;
  color: var(--color-text);
  padding: 16px 20px;
  border-radius: var(--radius);
  background: var(--color-section-alt);
  border: 1px solid var(--color-border);
}

.experience-item .company {
  font-weight: 700;
  font-size: 17px;
}

.experience-item .date {
  font-size: 14.5px;
  color: var(--color-text-secondary);
  margin-top: 2px;
}

/* Publications */
.year-filter {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 28px;
}

.year-btn {
  font-family: var(--font-body);
  font-size: 14px;
  font-weight: 600;
  padding: 6px 16px;
  border-radius: 20px;
  border: 1.5px solid var(--color-border);
  background: #fff;
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all 0.2s;
}

.year-btn:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.year-btn.active {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
}

.pub-year-group {
  margin-top: 28px;
}

.pub-year-group:first-of-type {
  margin-top: 0;
}

.pub-year-group.collapsed {
  display: none;
}

.pub-year {
  font-size: 15px;
  font-weight: 700;
  color: var(--color-tag-text);
  background: var(--color-tag-bg);
  display: inline-flex;
  align-items: center;
  padding: 5px 16px;
  border-radius: 6px;
  margin-bottom: 14px;
  border: 1px solid var(--color-accent-light);
}

.pub-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.pub-item {
  padding: 16px 20px;
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  transition: all 0.25s ease;
  background: #fff;
}

.pub-item:hover {
  box-shadow: 0 4px 20px var(--color-card-shadow);
  border-color: var(--color-accent-light);
  transform: translateY(-1px);
}

.pub-title {
  font-size: 16px;
  font-weight: 650;
  line-height: 1.55;
  color: var(--color-text);
}

.pub-title a {
  color: var(--color-text);
  transition: color 0.2s;
}

.pub-title a:hover {
  color: var(--color-accent);
}

.pub-authors {
  font-size: 14.5px;
  color: var(--color-text-secondary);
  margin-top: 5px;
  line-height: 1.65;
}

.pub-authors .me {
  font-weight: 700;
  color: var(--color-text);
}

.pub-meta {
  font-size: 14px;
  color: var(--color-text-secondary);
  margin-top: 5px;
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.pub-venue {
  font-style: italic;
}

.award {
  font-style: normal;
  font-weight: 700;
  color: var(--color-warm);
  background: var(--color-warm-light);
  padding: 1px 8px;
  border-radius: 4px;
  font-size: 12.5px;
}

.pub-link {
  font-size: 13px;
  font-weight: 500;
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: color 0.2s;
}

.pub-link::before {
  content: '[';
}

.pub-link::after {
  content: ']';
}

.pub-link:hover {
  color: var(--color-accent);
}

/* Projects */
.projects-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

.project-card {
  display: block;
  padding: 20px;
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  background: #fff;
  transition: all 0.25s ease;
  text-decoration: none;
  color: var(--color-text);
}

.project-card:hover {
  border-color: var(--color-accent-light);
  box-shadow: 0 4px 20px var(--color-card-shadow);
  transform: translateY(-2px);
}

.project-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 8px;
}

.project-name {
  font-size: 17px;
  font-weight: 700;
  color: var(--color-accent);
}

.project-stats {
  display: flex;
  gap: 12px;
}

.project-stats .stat {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 13px;
  font-weight: 500;
  color: var(--color-text-secondary);
}

.project-stats .stat svg {
  opacity: 0.6;
}

.project-desc {
  font-size: 14px;
  line-height: 1.6;
  color: var(--color-text-secondary);
}

.projects-more {
  margin-top: 18px;
  font-size: 14.5px;
  color: var(--color-text-secondary);
  text-align: center;
}

@media (max-width: 640px) {
  .projects-grid {
    grid-template-columns: 1fr;
  }
}

/* Awards */
.awards-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.award-item {
  font-size: 16px;
  padding: 16px 20px;
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  gap: 14px;
  transition: all 0.2s;
  background: #fff;
}

.award-item:hover {
  box-shadow: 0 2px 12px var(--color-card-shadow);
  transform: translateY(-1px);
}

.award-item .award-badge {
  font-size: 12.5px;
  font-weight: 700;
  color: var(--color-warm);
  background: var(--color-warm-light);
  border: 1px solid var(--color-warm-border);
  padding: 3px 12px;
  border-radius: 6px;
  white-space: nowrap;
  letter-spacing: 0.02em;
}

/* Service */
.service-content {
  font-size: 16px;
  color: var(--color-text);
  line-height: 1.85;
  padding: 16px 20px;
  border-radius: var(--radius);
  background: var(--color-section-alt);
  border: 1px solid var(--color-border);
}

/* Footer */
footer {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 40px 28px;
  text-align: center;
  font-size: 14px;
  color: #94a3b8;
  border-top: 1px solid var(--color-border);
}

/* Back to top */
.back-to-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 1px solid var(--color-border);
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(8px);
  color: var(--color-text-secondary);
  font-size: 18px;
  cursor: pointer;
  transition: all 0.2s;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 50;
}

.back-to-top:hover {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(75, 131, 199, 0.25);
}

/* Responsive */
@media (max-width: 640px) {
  body {
    font-size: 15.5px;
  }

  .hero {
    padding: 40px 0 32px;
  }

  .hero h1 {
    font-size: 30px;
  }

  .hero .affiliation {
    font-size: 15.5px;
  }

  nav .nav-inner {
    padding: 0 18px;
  }

  nav .nav-links {
    gap: 18px;
  }

  nav .nav-links a {
    font-size: 14px;
  }

  main {
    padding: 0 18px;
  }

  section h2 {
    font-size: 21px;
  }

  .pub-item {
    padding: 14px 16px;
  }

  .hero .external-links {
    gap: 8px;
  }

  .hero .external-links a {
    padding: 6px 14px;
    font-size: 13.5px;
  }

  .award-item {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }
}