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

:root {
  --color-bg: #fffdf7;
  --color-bg-alt: #fdf6e3;
  --color-text: #1a2332;
  --color-text-secondary: #4a5568;
  --color-text-muted: #718096;
  --color-primary: #1e3a5f;
  --color-accent: #2b6cb0;
  --color-accent-light: #ebf4ff;
  --color-border: #e2e8f0;
  --color-card: #ffffff;
  --color-hero-bg: #fdf6e3;
  --color-hero-text: #1a2332;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-serif: 'Source Serif 4', Georgia, 'Times New Roman', serif;
  --max-width: 960px;
  --nav-height: 64px;
  --transition: 0.25s ease;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
  scroll-padding-top: var(--nav-height);
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

img {
  max-width: 100%;
  height: auto;
}

::selection {
  background: var(--color-accent);
  color: white;
}

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

.section {
  padding: 80px 0;
}

.section-alt {
  background: var(--color-bg-alt);
}

.section-title {
  font-family: var(--font-serif);
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 40px;
  position: relative;
  padding-bottom: 12px;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 48px;
  height: 3px;
  background: var(--color-accent);
  border-radius: 2px;
}

.subsection-title {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-top: 40px;
  margin-bottom: 20px;
  letter-spacing: 0.01em;
}

.subsection-title:first-of-type {
  margin-top: 0;
}

/* ===== Navigation ===== */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: rgba(253, 246, 227, 0.95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  z-index: 1000;
  transition: box-shadow var(--transition);
}

.nav.scrolled {
  box-shadow: 0 1px 16px rgba(0, 0, 0, 0.15);
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--color-primary);
  letter-spacing: 0.01em;
}

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

.nav-links {
  display: flex;
  list-style: none;
  gap: 8px;
}

.nav-links a {
  color: var(--color-text-secondary);
  font-size: 0.875rem;
  font-weight: 500;
  padding: 6px 14px;
  border-radius: 6px;
  transition: all var(--transition);
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--color-primary);
  background: rgba(0, 0, 0, 0.05);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav-toggle span {
  width: 22px;
  height: 2px;
  background: var(--color-primary);
  border-radius: 1px;
  transition: all var(--transition);
}

/* ===== Hero ===== */
.hero {
  background: var(--color-hero-bg);
  color: var(--color-hero-text);
  padding-top: calc(var(--nav-height) + 60px);
  padding-bottom: 80px;
  min-height: 100vh;
  display: flex;
  align-items: center;
}

.hero-content {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  gap: 64px;
}

.hero-text {
  flex: 1;
}

.hero-greeting {
  font-size: 1rem;
  font-weight: 400;
  color: var(--color-text-muted);
  margin-bottom: 8px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.hero-name {
  font-family: var(--font-serif);
  font-size: 3.2rem;
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1.15;
  margin-bottom: 4px;
}

.hero-chinese {
  font-size: 1.25rem;
  color: var(--color-text-muted);
  margin-bottom: 20px;
  font-weight: 300;
}

.hero-title {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 6px;
}

.hero-affiliation {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: 28px;
}

.hero-links {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 24px;
}

.btn {
  display: inline-flex;
  align-items: center;
  padding: 10px 22px;
  font-size: 0.875rem;
  font-weight: 500;
  border-radius: 8px;
  transition: all var(--transition);
  letter-spacing: 0.01em;
}

.btn-primary {
  background: var(--color-accent);
  color: #fff;
}

.btn-primary:hover {
  background: #2c5282;
  color: #fff;
}

.btn-outline {
  border: 1.5px solid var(--color-border);
  color: var(--color-text-secondary);
}

.btn-outline:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  background: rgba(43, 108, 176, 0.05);
}

.hero-icons {
  display: flex;
  gap: 16px;
}

.hero-icons a {
  color: var(--color-text-muted);
  transition: color var(--transition);
}

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

.hero-image {
  flex-shrink: 0;
  width: 280px;
  height: 280px;
}

.hero-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 50%;
  border: 4px solid rgba(0, 0, 0, 0.08);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.1);
}

/* ===== About ===== */
.about-content p {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  margin-bottom: 16px;
  max-width: 720px;
}

.about-keywords {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 24px;
}

.keyword {
  background: var(--color-accent-light);
  color: var(--color-accent);
  padding: 6px 16px;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 500;
}

/* ===== Research ===== */
.research-card {
  background: var(--color-card);
  border-radius: 12px;
  padding: 32px;
  margin-bottom: 20px;
  border: 1px solid var(--color-border);
  transition: box-shadow var(--transition);
}

.research-card:hover {
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
}

.research-card-header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 16px;
}

.research-number {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-accent);
  opacity: 0.5;
  line-height: 1;
}

.research-card h3 {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--color-primary);
}

.research-card p {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  margin-bottom: 12px;
  line-height: 1.75;
}

.research-card p:last-child {
  margin-bottom: 0;
}

/* ===== Publications ===== */
.pub-list {
  list-style: none;
  counter-reset: pub-counter 9;
}

.pub-item {
  counter-increment: pub-counter -1;
  padding: 20px 0 20px 48px;
  position: relative;
  border-bottom: 1px solid var(--color-border);
}

.pub-item:last-child {
  border-bottom: none;
}

.pub-item::before {
  content: '[' counter(pub-counter) ']';
  position: absolute;
  left: 0;
  top: 20px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-accent);
  font-variant-numeric: tabular-nums;
}

.pub-item.pub-inprep {
  opacity: 0.7;
}

.pub-authors {
  font-size: 0.92rem;
  color: var(--color-text-secondary);
}

.pub-authors strong {
  color: var(--color-text);
}

.pub-title {
  display: block;
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--color-text);
  margin: 4px 0;
}

.pub-venue {
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

.pub-link {
  display: inline-flex;
  align-items: center;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-accent);
  padding: 3px 10px;
  border: 1px solid var(--color-accent);
  border-radius: 4px;
  margin-top: 6px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  transition: all var(--transition);
}

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

/* ===== Talks ===== */
.talks-list {
  list-style: none;
  counter-reset: talk-counter 15;
}

.talk-item {
  counter-increment: talk-counter -1;
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  padding: 14px 0 14px 48px;
  position: relative;
  border-bottom: 1px solid var(--color-border);
  gap: 16px;
}

.talk-item:last-child {
  border-bottom: none;
}

.talk-item::before {
  content: '[' counter(talk-counter) ']';
  position: absolute;
  left: 0;
  top: 14px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-accent);
  font-variant-numeric: tabular-nums;
}

.talk-venue {
  font-size: 0.92rem;
  color: var(--color-text-secondary);
  flex: 1;
}

.talk-type {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-accent);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  white-space: nowrap;
}

/* ===== Outreach ===== */
.outreach-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

.outreach-card {
  background: var(--color-card);
  border-radius: 12px;
  padding: 28px;
  border: 1px solid var(--color-border);
  transition: box-shadow var(--transition);
}

.outreach-card:hover {
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
}

.outreach-icon {
  color: var(--color-accent);
  margin-bottom: 16px;
}

.outreach-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-bottom: 6px;
  line-height: 1.4;
}

.outreach-card h3 a {
  color: var(--color-primary);
}

.outreach-card h3 a:hover {
  color: var(--color-accent);
}

.outreach-role {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-accent);
  margin-bottom: 10px;
}

.outreach-card p:last-child {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  line-height: 1.65;
}

/* ===== CV ===== */
.cv-grid {
  display: flex;
  flex-direction: column;
  gap: 40px;
}

.cv-block-title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-bottom: 20px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--color-border);
}

.cv-entry {
  display: flex;
  gap: 24px;
  margin-bottom: 24px;
}

.cv-entry:last-child {
  margin-bottom: 0;
}

.cv-date {
  flex-shrink: 0;
  width: 180px;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-text-muted);
  padding-top: 2px;
}

.cv-position {
  font-weight: 600;
  font-size: 1rem;
  color: var(--color-text);
  margin-bottom: 2px;
}

.cv-institution {
  font-size: 0.92rem;
  color: var(--color-text-secondary);
}

.cv-advisor {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  font-style: italic;
  margin-top: 2px;
}

/* ===== Footer ===== */
.footer {
  background: #f5edda;
  color: var(--color-text-secondary);
  padding: 32px 0;
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer p {
  font-size: 0.85rem;
}

.footer-links {
  display: flex;
  gap: 20px;
}

.footer-links a {
  color: var(--color-text-muted);
  font-size: 0.85rem;
  font-weight: 500;
  transition: color var(--transition);
}

.footer-links a:hover {
  color: var(--color-primary);
}

/* ===== Animations ===== */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  :root {
    --nav-height: 56px;
  }

  .nav-toggle {
    display: flex;
  }

  .nav-links {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: rgba(253, 246, 227, 0.98);
    backdrop-filter: blur(12px);
    flex-direction: column;
    padding: 16px 24px;
    gap: 4px;
    transform: translateY(-100%);
    opacity: 0;
    pointer-events: none;
    transition: all 0.3s ease;
  }

  .nav-links.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  .nav-links a {
    display: block;
    padding: 10px 14px;
  }

  .hero {
    padding-top: calc(var(--nav-height) + 40px);
    padding-bottom: 60px;
    min-height: auto;
  }

  .hero-content {
    flex-direction: column-reverse;
    gap: 32px;
    text-align: center;
  }

  .hero-image {
    width: 180px;
    height: 180px;
  }

  .hero-name {
    font-size: 2.2rem;
  }

  .hero-links {
    justify-content: center;
  }

  .hero-icons {
    justify-content: center;
  }

  .section {
    padding: 56px 0;
  }

  .section-title {
    font-size: 1.6rem;
  }

  .research-card {
    padding: 24px;
  }

  .outreach-grid {
    grid-template-columns: 1fr;
  }

  .cv-entry {
    flex-direction: column;
    gap: 4px;
  }

  .cv-date {
    width: auto;
  }

  .talk-item {
    flex-direction: column;
    gap: 4px;
  }

  .footer-content {
    flex-direction: column;
    gap: 12px;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .hero-name {
    font-size: 1.8rem;
  }

  .hero-links {
    flex-direction: column;
    align-items: center;
  }

  .btn {
    width: 100%;
    justify-content: center;
  }

  .about-keywords {
    justify-content: center;
  }
}