:root {
  --color-bg: #ffffff;
  --color-surface: #f7f7f8;
  --color-border: #e5e7eb;
  --color-text: #111827;
  --color-text-soft: #374151;
  --color-muted: #6b7280;
  --color-accent: #1d4ed8;
  --color-accent-dark: #1e3a8a;
  --color-accent-soft: #eef2ff;
  --max-width: 1040px;
  --radius: 10px;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 4px 14px rgba(0, 0, 0, 0.07);
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-serif: 'Lora', Georgia, serif;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text-soft);
  background: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color 0.15s ease;
}
a:hover { color: var(--color-accent-dark); text-decoration: underline; }

strong { color: var(--color-text); font-weight: 600; }
em { color: var(--color-text); }

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ------- Header / Nav ------- */
.site-header {
  border-bottom: 1px solid var(--color-border);
  background: rgba(255,255,255,0.92);
  backdrop-filter: saturate(180%) blur(8px);
  position: sticky;
  top: 0;
  z-index: 50;
}
.nav-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}
.brand {
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--color-text);
  font-size: 1rem;
}
.brand:hover { text-decoration: none; color: var(--color-accent); }
.main-nav { display: flex; flex-wrap: wrap; }
.main-nav a {
  color: var(--color-text-soft);
  margin-left: 1.15rem;
  font-weight: 500;
  font-size: 0.92rem;
  position: relative;
  white-space: nowrap;
}
.main-nav a:hover { color: var(--color-accent); text-decoration: none; }
.main-nav a.active { color: var(--color-accent); font-weight: 600; }

.nav-toggle {
  display: none;
  background: none;
  border: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 6px;
}
.nav-toggle span {
  width: 22px;
  height: 2px;
  background: var(--color-text);
  display: block;
}

@media (max-width: 820px) {
  .main-nav {
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    background: #fff;
    flex-direction: column;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--color-border);
    display: none;
  }
  .main-nav.open { display: flex; }
  .main-nav a { margin: 0.4rem 0; }
  .nav-toggle { display: flex; }
}

/* ------- Hero (Xin Qiu style) ------- */
.hero {
  padding: 1.75rem 1.5rem 2rem;
}
.hero-grid {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 2.5rem;
  align-items: center;
}
.avatar-wrap { text-align: center; }
.avatar {
  width: 220px;
  height: 220px;
  border-radius: 50%;
  background: linear-gradient(135deg, #1d4ed8, #7c3aed);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 4.5rem;
  letter-spacing: 0.02em;
  box-shadow: var(--shadow-md);
  border: 3px solid #fff;
  outline: 1px solid var(--color-border);
}
.avatar-img {
  object-fit: cover;
  background: var(--color-surface);
  display: block;
}
.social-links {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  gap: 0.55rem;
  flex-wrap: wrap;
}
.social-links a {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: var(--color-surface);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text);
  border: 1px solid var(--color-border);
  transition: all 0.15s ease;
  font-size: 0.95rem;
}
.social-links a:hover {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
  text-decoration: none;
  transform: translateY(-1px);
}

.hero-text h1 {
  font-family: var(--font-serif);
  font-size: 2.4rem;
  margin: 0 0 0.45rem;
  letter-spacing: -0.02em;
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.15;
}
.hero-tagline {
  font-size: 1.05rem;
  font-weight: 700;
  color: #000;
  margin: 0 0 0.6rem;
  line-height: 1.35;
}
.hero-role {
  font-size: 1.05rem;
  color: var(--color-text);
  margin: 0 0 0.25rem;
  font-weight: 500;
}
.hero-affiliation {
  font-size: 0.98rem;
  color: var(--color-muted);
  margin: 0 0 1rem;
}
.hero-affiliation a { color: var(--color-accent); }

@media (max-width: 760px) {
  .hero { padding-top: 1.25rem; }
  .hero-grid { grid-template-columns: 1fr; gap: 1.25rem; text-align: center; }
  .hero-text h1 { font-size: 1.95rem; }
  .avatar { width: 160px; height: 160px; font-size: 3rem; margin: 0 auto; }
  .social-links { justify-content: center; }
}

/* ------- Metrics ------- */
.metrics {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.6rem;
  margin: 0;
}
.metric-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 0.7rem 0.4rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
  color: var(--color-text);
  text-decoration: none;
  transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease;
}
.metric-card:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
  border-color: var(--color-accent);
  text-decoration: none;
  color: var(--color-text);
}
.metric-value {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--color-accent);
  line-height: 1;
}
.metric-label {
  font-size: 0.72rem;
  color: var(--color-muted);
  margin-top: 0.25rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

@media (max-width: 480px) {
  .metric-value { font-size: 1.25rem; }
  .metrics { grid-template-columns: repeat(2, 1fr); }
}

/* ------- Sections ------- */
.section {
  padding: 2rem 1.5rem;
  border-top: 1px solid var(--color-border);
}
.block-heading {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 600;
  margin: 1.5rem 0 0.6rem;
  color: var(--color-text);
  letter-spacing: -0.01em;
}
.block-heading:first-child { margin-top: 0; }
.featured-heading {
  font-family: var(--font-serif);
  font-size: 1.4rem;
  font-weight: 600;
  margin: 0 0 1rem;
  color: var(--color-text);
  letter-spacing: -0.01em;
}

/* Edu list simple (Xin Qiu style) */
.edu-list-simple {
  list-style: none;
  padding: 0;
  margin: 0;
}
.edu-list-simple li {
  display: flex;
  gap: 0.85rem;
  align-items: flex-start;
  padding: 0.45rem 0;
  font-size: 0.95rem;
}
.edu-icon {
  color: var(--color-accent);
  margin-top: 0.25rem;
  flex-shrink: 0;
}

/* Featured publications — clean stacked entries (Xin Qiu inspired) */
.featured-pubs {
  display: flex;
  flex-direction: column;
}
.featured-pub {
  padding: 1rem 0 1.1rem;
  border-bottom: 1px solid var(--color-border);
}
.featured-pub:last-child { border-bottom: none; padding-bottom: 0; }
.conf-tag {
  display: inline-block;
  background: var(--color-accent);
  color: #fff;
  padding: 0.18rem 0.7rem;
  border-radius: 4px;
  font-size: 0.74rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.featured-pub h3 {
  margin: 0.55rem 0 0.3rem;
  font-size: 1.08rem;
  font-weight: 600;
  line-height: 1.4;
}
.featured-pub h3 a { color: var(--color-text); }
.featured-pub h3 a:hover { color: var(--color-accent); }
.featured-meta {
  margin: 0;
  color: var(--color-muted);
  font-size: 0.88rem;
  line-height: 1.5;
}
.see-more {
  margin: 1rem 0 0;
  font-size: 0.92rem;
}
.section-tight { padding: 1.5rem 1.5rem; }
.section h2 {
  font-family: var(--font-serif);
  font-size: 1.4rem;
  margin: 0 0 0.85rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--color-text);
}
.section h2.mt { margin-top: 1.25rem; }
.section h3 {
  font-size: 1.02rem;
  margin: 0 0 0.3rem;
  font-weight: 600;
  color: var(--color-text);
}
.section p { margin: 0 0 0.75rem; }
.section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 0.85rem;
}
.section-head h2 { margin: 0; }
.see-link { font-size: 0.88rem; color: var(--color-accent); }
.compact-p { margin: 0; }

/* Two-column */
.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2.5rem;
}
.two-col h2 { margin-bottom: 0.6rem; }
@media (max-width: 760px) {
  .two-col { grid-template-columns: 1fr; gap: 1.25rem; }
}

/* Interest list */
.interest-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.25rem;
}
.interest-list li {
  position: relative;
  padding-left: 1.1rem;
  color: var(--color-text-soft);
  font-size: 0.95rem;
}
.interest-list li::before {
  content: "▸";
  color: var(--color-accent);
  position: absolute;
  left: 0;
  top: 0;
}
.interest-list.compact li { line-height: 1.5; }

.interest-cta {
  margin: 0.9rem 0 0;
  padding: 0.7rem 0.95rem;
  border-left: 3px solid var(--color-accent);
  background: rgba(0, 0, 0, 0.025);
  font-size: 0.95rem;
  color: var(--color-text);
  border-radius: 2px;
}
.interest-cta a { color: var(--color-accent); font-weight: 500; }

/* Education compact */
.edu-compact {
  list-style: none;
  padding: 0;
  margin: 0;
}
.edu-compact li {
  margin-bottom: 0.7rem;
  padding-bottom: 0.7rem;
  border-bottom: 1px dashed var(--color-border);
  font-size: 0.95rem;
}
.edu-compact li:last-child { border-bottom: none; padding-bottom: 0; margin-bottom: 0; }

/* Existing Education cards (used on experience.html) */
.edu-list { display: flex; flex-direction: column; gap: 0.85rem; }
.edu-item {
  padding: 0.9rem 1.1rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
}
.edu-meta {
  color: var(--color-muted);
  margin: 0 0 0.3rem;
  font-size: 0.88rem;
}
.edu-detail { margin: 0; font-size: 0.95rem; }

/* ------- Compact publications list ------- */
.pub-compact {
  list-style: none;
  padding: 0;
  margin: 0;
  counter-reset: pub;
}
.pub-compact li {
  display: grid;
  grid-template-columns: 80px 1fr;
  grid-template-areas:
    "year title"
    "year meta";
  column-gap: 1.25rem;
  row-gap: 0.2rem;
  padding: 0.8rem 0;
  border-bottom: 1px solid var(--color-border);
}
.pub-compact .pub-year { grid-area: year; align-self: start; padding-top: 0.15rem; }
.pub-compact .pub-title { grid-area: title; }
.pub-compact .pub-meta { grid-area: meta; }
.pub-compact li:last-child { border-bottom: none; }
.pub-year {
  font-family: var(--font-serif);
  color: var(--color-accent);
  font-size: 0.92rem;
  font-variant-numeric: tabular-nums;
  font-weight: 600;
  letter-spacing: 0.02em;
}
.pub-title {
  display: block;
  font-weight: 600;
  color: var(--color-text);
  font-size: 0.97rem;
  line-height: 1.4;
}
.pub-title:hover { color: var(--color-accent); text-decoration: none; }
.pub-meta {
  display: block;
  color: var(--color-muted);
  font-size: 0.86rem;
  margin-top: 0.15rem;
  line-height: 1.45;
}

@media (max-width: 540px) {
  .pub-compact li {
    grid-template-columns: 1fr;
    grid-template-areas:
      "year"
      "title"
      "meta";
    row-gap: 0.15rem;
  }
  .pub-compact .pub-year { padding-top: 0; }
  .pub-year { font-size: 0.85rem; }
}

/* ------- Compact experience timeline (homepage) ------- */
.exp-compact {
  list-style: none;
  padding: 0;
  margin: 0;
}
.exp-compact li {
  padding: 0.45rem 0;
  font-size: 0.95rem;
  border-bottom: 1px solid var(--color-border);
}
.exp-compact li:last-child { border-bottom: none; }
.exp-when {
  display: inline-block;
  width: 110px;
  color: var(--color-muted);
  font-size: 0.85rem;
  font-variant-numeric: tabular-nums;
  margin-right: 0.4rem;
}
@media (max-width: 540px) {
  .exp-when { display: block; width: auto; margin-bottom: 0.1rem; }
}

/* ------- Full experience page ------- */
.timeline { display: flex; flex-direction: column; gap: 1rem; }
.exp-item {
  padding: 1rem 1.25rem;
  border: 1px solid var(--color-border);
  border-left: 4px solid var(--color-accent);
  border-radius: var(--radius);
  background: var(--color-surface);
}
.exp-role {
  font-weight: 600;
  font-size: 1.05rem;
  margin: 0 0 0.15rem;
  color: var(--color-text);
}
.exp-org {
  color: var(--color-accent);
  font-weight: 500;
  margin: 0 0 0.1rem;
}
.exp-meta {
  color: var(--color-muted);
  font-size: 0.88rem;
  margin: 0 0 0.65rem;
}
.exp-item ul { margin: 0; padding-left: 1.15rem; }
.exp-item li { margin-bottom: 0.3rem; font-size: 0.94rem; }

/* ------- Projects ------- */
.project-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1rem;
}
.project-card {
  padding: 1.1rem 1.2rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
  transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease;
}
.project-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  border-color: var(--color-accent);
}
.project-card h3 { margin-top: 0; }
.project-tag {
  display: inline-block;
  font-size: 0.72rem;
  background: var(--color-accent-soft);
  color: var(--color-accent-dark);
  padding: 0.1rem 0.5rem;
  border-radius: 999px;
  margin-right: 0.25rem;
  margin-top: 0.4rem;
  font-weight: 500;
  letter-spacing: 0.02em;
}

/* ------- Skill grid ------- */
.skill-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 0.85rem;
}
.skill-card {
  padding: 0.9rem 1.1rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
}
.skill-card h3 {
  font-size: 0.95rem;
  margin: 0 0 0.4rem;
  color: var(--color-accent-dark);
}
.skill-card p { margin: 0; font-size: 0.9rem; }

/* ------- Page header ------- */
.page-header {
  padding: 1.25rem 1.5rem 0.5rem;
}
.page-header h1 {
  font-family: var(--font-serif);
  font-size: 2rem;
  margin: 0 0 0.4rem;
  letter-spacing: -0.02em;
  color: var(--color-text);
}
.page-header p { color: var(--color-muted); margin: 0; font-size: 0.95rem; }

/* ------- Footer ------- */
.site-footer {
  margin-top: 2rem;
  padding: 1.5rem 0;
  border-top: 1px solid var(--color-border);
  background: var(--color-surface);
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.footer-inner p { margin: 0; font-size: 0.86rem; }
.muted { color: var(--color-muted); }

/* Selection */
::selection { background: var(--color-accent-soft); color: var(--color-accent-dark); }