/* ===== Design tokens ===== */
:root {
  --ink: #17202b;
  --muted: #5c6b7a;
  --accent: #0e6fd8;
  --accent-2: #00c2ff;
  --accent-grad: linear-gradient(135deg, #00c2ff, #0e6fd8);
  --navy-900: #071427;
  --navy-800: #0a1d38;
  --navy-700: #0f2c52;
  --bg: #ffffff;
  --soft: #f1f6fb;
  --line: #e2eaf2;
  --white: #ffffff;
  --shadow: 0 14px 40px rgba(7, 20, 39, 0.10);
  --shadow-lg: 0 24px 60px rgba(7, 20, 39, 0.16);
  --radius: 16px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 76px;
}

body {
  margin: 0;
  font-family: "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.65;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
}

img {
  max-width: 100%;
  display: block;
}

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

a:hover {
  text-decoration: underline;
}

.container {
  width: min(1100px, 92%);
  margin: 0 auto;
}

/* ===== Header ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-weight: 700;
  font-size: 18px;
}

.brand:hover {
  text-decoration: none;
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 36px;
  height: 36px;
  padding: 0 10px;
  border-radius: 999px;
  background: var(--accent-grad);
  color: var(--white);
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: 0.5px;
  box-shadow: 0 6px 16px rgba(14, 111, 216, 0.35);
}

.main-nav {
  display: flex;
  align-items: center;
  gap: 22px;
}

.main-nav a {
  color: var(--muted);
  font-size: 15px;
  font-weight: 500;
}

.main-nav a:hover {
  color: var(--accent);
  text-decoration: none;
}

.main-nav .nav-cn {
  color: var(--accent);
  border: 1.5px solid var(--accent);
  padding: 6px 14px;
  border-radius: 999px;
  font-weight: 600;
}

.main-nav .nav-cn:hover {
  background: var(--accent);
  color: var(--white);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: 0;
  cursor: pointer;
  padding: 8px;
}

.nav-toggle span {
  width: 22px;
  height: 2px;
  background: var(--ink);
  border-radius: 2px;
}

/* ===== Hero ===== */
.hero {
  position: relative;
  overflow: hidden;
  background: radial-gradient(1100px 520px at 82% -10%, rgba(0, 194, 255, 0.28), transparent 60%),
    radial-gradient(900px 500px at -10% 110%, rgba(14, 111, 216, 0.32), transparent 55%),
    linear-gradient(160deg, var(--navy-900) 0%, var(--navy-800) 55%, var(--navy-700) 100%);
  color: var(--white);
  padding: 78px 0 0;
}

.hero-bg {
  position: absolute;
  inset: 0;
  pointer-events: none;
  opacity: 0.5;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.055) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.055) 1px, transparent 1px);
  background-size: 52px 52px;
  mask-image: radial-gradient(ellipse 90% 70% at 50% 20%, black 20%, transparent 75%);
  -webkit-mask-image: radial-gradient(ellipse 90% 70% at 50% 20%, black 20%, transparent 75%);
}

.hero::after {
  content: "";
  position: absolute;
  width: 480px;
  height: 480px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(0, 194, 255, 0.20), transparent 65%);
  top: -180px;
  right: -120px;
  animation: floatOrb 14s ease-in-out infinite alternate;
  pointer-events: none;
}

@keyframes floatOrb {
  from { transform: translate(0, 0) scale(1); }
  to { transform: translate(-60px, 45px) scale(1.15); }
}

.hero-inner {
  position: relative;
  display: grid;
  grid-template-columns: 1.5fr 0.9fr;
  gap: 48px;
  align-items: center;
  padding-bottom: 64px;
}

.hero-eyebrow {
  margin: 0 0 16px;
  font-size: 13.5px;
  letter-spacing: 1.6px;
  text-transform: uppercase;
  color: rgba(255, 255, 255, 0.72);
}

.hero-name {
  margin: 0 0 10px;
  font-size: clamp(44px, 7vw, 68px);
  line-height: 1.05;
  letter-spacing: -1px;
  background: linear-gradient(90deg, #ffffff 0%, #7fdcff 60%, #00c2ff 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-sub {
  margin: 0 0 12px;
  font-size: 20px;
  font-weight: 500;
  color: rgba(255, 255, 255, 0.94);
}

.hero-tagline {
  margin: 0 0 32px;
  font-size: 15.5px;
  color: rgba(255, 255, 255, 0.72);
}

.hero-tagline .dot {
  margin: 0 8px;
  color: var(--accent-2);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}

.btn {
  display: inline-block;
  padding: 12px 26px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 15px;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
}

.btn:hover {
  transform: translateY(-2px);
  text-decoration: none;
}

.btn-glow {
  background: var(--accent-grad);
  color: var(--white);
  box-shadow: 0 10px 28px rgba(0, 194, 255, 0.35);
}

.btn-glow:hover {
  box-shadow: 0 16px 36px rgba(0, 194, 255, 0.45);
}

.btn-ghost {
  border: 1.5px solid rgba(255, 255, 255, 0.7);
  color: var(--white);
}

.btn-ghost:hover {
  background: rgba(255, 255, 255, 0.12);
}

.btn-primary {
  background: var(--accent);
  color: var(--white);
  box-shadow: 0 10px 24px rgba(14, 111, 216, 0.3);
}

.hero-side {
  position: relative;
  text-align: center;
}

.avatar-ring {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 240px;
  height: 240px;
  transform: translate(-50%, -58%);
  border-radius: 50%;
  background: conic-gradient(from 0deg, transparent 0deg, rgba(0, 194, 255, 0.55) 90deg, transparent 180deg, rgba(14, 111, 216, 0.55) 270deg, transparent 360deg);
  animation: spinRing 10s linear infinite;
  pointer-events: none;
}

@keyframes spinRing {
  to { transform: translate(-50%, -58%) rotate(360deg); }
}

.avatar {
  position: relative;
  width: 190px;
  height: 190px;
  margin: 0 auto 16px;
  border-radius: 50%;
  background: linear-gradient(150deg, rgba(255, 255, 255, 0.18), rgba(255, 255, 255, 0.05));
  border: 2px solid rgba(255, 255, 255, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 42px;
  font-weight: 700;
  letter-spacing: 0.5px;
  color: var(--white);
  box-shadow: 0 24px 60px rgba(0, 0, 0, 0.35);
}

.avatar-photo {
  position: relative;
  width: 190px;
  height: 190px;
  margin: 0 auto 16px;
  border-radius: 50%;
  object-fit: cover;
  border: 3px solid rgba(255, 255, 255, 0.6);
  box-shadow: 0 24px 60px rgba(0, 0, 0, 0.35);
}

.avatar-caption {
  position: relative;
  margin: 0;
  font-size: 14px;
  color: rgba(255, 255, 255, 0.8);
}

/* ===== Hero stats ===== */
.stats-row {
  position: relative;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.14);
  border-radius: var(--radius) var(--radius) 0 0;
  overflow: hidden;
  backdrop-filter: blur(8px);
}

.stat {
  background: rgba(10, 29, 56, 0.55);
  padding: 26px 18px;
  text-align: center;
}

.stat-num {
  font-size: 36px;
  font-weight: 800;
  background: var(--accent-grad);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.stat-plus {
  font-size: 26px;
  font-weight: 800;
  color: var(--accent-2);
}

.stat-label {
  display: block;
  margin-top: 4px;
  font-size: 13px;
  color: rgba(255, 255, 255, 0.72);
}

/* ===== 中文说明条（帮助百度识别） ===== */
.cn-strip {
  background: linear-gradient(90deg, #e8f4ff, #f5faff);
  border-bottom: 1px solid var(--line);
}

.cn-strip p {
  margin: 0;
  padding: 18px 0;
  font-size: 15px;
  color: #24405e;
}

.cn-strip strong {
  color: var(--accent);
}

/* ===== Sections ===== */
.section {
  padding: 76px 0;
}

.section-soft {
  background: var(--soft);
}

.section h2 {
  margin: 0 0 10px;
  font-size: 34px;
  letter-spacing: -0.4px;
}

.section-index {
  margin: 0 0 6px;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 2px;
  text-transform: uppercase;
  background: var(--accent-grad);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.section-note {
  margin: 0 0 30px;
  color: var(--muted);
}

.card {
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 28px;
}

/* ===== About ===== */
.about-grid {
  display: grid;
  grid-template-columns: 1.6fr 1fr;
  gap: 40px;
  align-items: start;
  margin-top: 28px;
}

.about-main p {
  color: #33414f;
}

.about-card h3 {
  margin: 0 0 18px;
  font-size: 18px;
}

.fact-list {
  margin: 0;
}

.fact-list div {
  padding: 10px 0;
  border-bottom: 1px dashed var(--line);
}

.fact-list div:last-child {
  border-bottom: 0;
}

.fact-list dt {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--muted);
  margin-bottom: 2px;
}

.fact-list dd {
  margin: 0;
  font-weight: 500;
  font-size: 15px;
  overflow-wrap: anywhere;
}

/* ===== Timeline ===== */
.timeline-title {
  margin: 0 0 20px;
  font-size: 18px;
}

.timeline-wrap .timeline-title {
  margin-top: 32px;
}

.timeline-wrap .timeline-title:first-child {
  margin-top: 0;
}

.timeline-wrap {
  margin-top: 32px;
}

.timeline-wrap .timeline + .timeline {
  margin-top: 10px;
}

.timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  position: relative;
}

.timeline::before {
  content: "";
  position: absolute;
  left: 9px;
  top: 6px;
  bottom: 6px;
  width: 2px;
  background: linear-gradient(180deg, var(--accent-2), var(--accent));
  border-radius: 2px;
}

.timeline-item {
  position: relative;
  padding: 0 0 28px 40px;
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.tl-dot {
  position: absolute;
  left: 0;
  top: 6px;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--white);
  border: 5px solid var(--accent);
  box-shadow: 0 0 0 4px rgba(14, 111, 216, 0.15);
}

.tl-date {
  margin: 0 0 4px;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.6px;
  text-transform: uppercase;
  color: var(--accent);
}

.tl-body h4 {
  margin: 0 0 3px;
  font-size: 17px;
}

.tl-body p:last-child {
  margin: 0;
  color: var(--muted);
  font-size: 15px;
}

/* ===== Research chips ===== */
.chips {
  list-style: none;
  margin: 28px 0 26px;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.chip {
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 9px 18px;
  font-size: 15px;
  font-weight: 500;
  color: #33414f;
  box-shadow: 0 2px 8px rgba(7, 20, 39, 0.04);
}

.chip-core {
  background: var(--accent-grad);
  border-color: transparent;
  color: var(--white);
  box-shadow: 0 8px 20px rgba(14, 111, 216, 0.28);
}

.research-note {
  max-width: 760px;
  color: var(--muted);
  margin: 0;
}

/* ===== Publications ===== */
.pub-list {
  margin: 0;
  padding: 0;
  display: grid;
  gap: 14px;
  counter-reset: pub;
}

.pub-item {
  position: relative;
  list-style: none;
  counter-increment: pub;
  background: var(--white);
  border: 1px solid var(--line);
  border-left: 4px solid transparent;
  border-radius: 12px;
  padding: 18px 20px 18px 58px;
  color: #33414f;
  transition: border-color 0.2s ease, box-shadow 0.2s ease, transform 0.2s ease;
}

.pub-item::before {
  content: counter(pub);
  position: absolute;
  left: 18px;
  top: 18px;
  width: 28px;
  height: 28px;
  border-radius: 8px;
  background: var(--soft);
  color: var(--accent);
  font-weight: 700;
  font-size: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.pub-item:hover {
  border-left-color: var(--accent);
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}

.pub-role {
  display: inline-block;
  background: linear-gradient(135deg, rgba(0, 194, 255, 0.14), rgba(14, 111, 216, 0.14));
  color: var(--accent);
  font-size: 12px;
  font-weight: 700;
  border-radius: 6px;
  padding: 2px 9px;
  margin-right: 6px;
  vertical-align: 1px;
}

.pub-item em {
  font-style: italic;
}

/* ===== Projects ===== */
.project-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 20px;
}

.project-card {
  position: relative;
  padding: 26px 24px 24px;
  overflow: hidden;
}

.project-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: var(--accent-grad);
}

.project-card h3 {
  margin: 0 0 12px;
  font-size: 16.5px;
  line-height: 1.45;
}

.project-meta {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.7;
}

/* ===== Teaching ===== */
.teaching-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-top: 28px;
}

.teaching-card h3 {
  margin: 0 0 14px;
  font-size: 18px;
}

.teaching-card ul {
  margin: 0;
  padding-left: 20px;
  color: #33414f;
}

.teaching-card li + li {
  margin-top: 8px;
}

/* ===== Honors & service ===== */
.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-top: 28px;
}

.honors-card h3 {
  margin: 0 0 14px;
  font-size: 18px;
}

.check-list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 12px;
  color: #33414f;
}

.check-list li {
  position: relative;
  padding-left: 28px;
}

.check-list li::before {
  content: "✓";
  position: absolute;
  left: 0;
  top: 1px;
  width: 19px;
  height: 19px;
  border-radius: 50%;
  background: var(--accent-grad);
  color: var(--white);
  font-size: 11px;
  font-weight: 800;
  display: flex;
  align-items: center;
  justify-content: center;
}

.callout {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px 24px;
  margin-top: 28px;
  border: 1px solid rgba(14, 111, 216, 0.25);
  background: linear-gradient(135deg, #f2f8ff, #ffffff);
}

.callout h3 {
  margin: 0;
  font-size: 18px;
  flex-basis: 100%;
}

.callout p {
  margin: 0;
  flex: 1 1 420px;
  color: var(--muted);
}

/* ===== Contact ===== */
.contact {
  position: relative;
  overflow: hidden;
  background: radial-gradient(900px 460px at 85% -10%, rgba(0, 194, 255, 0.24), transparent 60%),
    linear-gradient(160deg, var(--navy-900), var(--navy-800));
  color: var(--white);
  text-align: center;
}

.contact .contact-index {
  -webkit-text-fill-color: var(--accent-2);
}

.contact h2 {
  color: var(--white);
}

.contact-lead {
  margin: 0 auto 30px;
  max-width: 600px;
  color: rgba(255, 255, 255, 0.86);
  line-height: 1.9;
}

.contact-lead a {
  color: var(--accent-2);
  font-weight: 700;
}

.contact .hero-actions {
  justify-content: center;
}

.contact-links {
  margin: 30px 0 0;
  font-size: 14px;
  color: rgba(255, 255, 255, 0.72);
}

.contact-links a {
  color: var(--white);
}

/* ===== Footer ===== */
.site-footer {
  background: #071220;
  color: #92a5b8;
  padding: 30px 0;
  font-size: 14px;
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 10px;
}

.footer-inner p {
  margin: 0;
}

.footer-cn {
  margin-bottom: 4px !important;
  color: #c6d5e4;
}

.footer-inner a {
  color: #c6d5e4;
}

/* ===== Scroll reveal ===== */
.reveal {
  opacity: 0;
  transform: translateY(26px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.visible {
  opacity: 1;
  transform: none;
}

/* ===== Responsive ===== */
@media (max-width: 900px) {
  .hero {
    padding: 52px 0 0;
  }

  .hero-inner {
    grid-template-columns: 1fr;
    gap: 40px;
    text-align: center;
    padding-bottom: 48px;
  }

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

  .avatar-ring {
    width: 200px;
    height: 200px;
  }

  .avatar,
  .avatar-photo {
    width: 152px;
    height: 152px;
    font-size: 34px;
  }

  .stats-row {
    grid-template-columns: repeat(2, 1fr);
    border-radius: 0;
  }

  .stat {
    padding: 20px 14px;
  }

  .about-grid,
  .teaching-grid,
  .two-col {
    grid-template-columns: 1fr;
    gap: 26px;
  }

  .nav-toggle {
    display: flex;
  }

  .main-nav {
    display: none;
    position: absolute;
    top: 68px;
    left: 0;
    right: 0;
    background: var(--white);
    border-bottom: 1px solid var(--line);
    box-shadow: var(--shadow);
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 10px 0 16px;
  }

  .main-nav.open {
    display: flex;
  }

  .main-nav a {
    padding: 12px 24px;
    font-size: 16px;
  }

  .main-nav .nav-cn {
    margin: 8px 24px 0;
    text-align: center;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .hero::after,
  .avatar-ring {
    animation: none;
  }

  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .btn,
  .pub-item,
  .project-card {
    transition: none;
  }
}