/* ===== Yali Huang — academic site ===== */
:root {
  --ink: #1a1a1a;
  --muted: #5b6470;
  --line: #e3e6ea;
  --bg: #ffffff;
  --bg-soft: #f7f8fa;
  --accent: #1f4e79;       /* deep academic blue */
  --accent-soft: #eaf0f6;
  --maxw: 980px;
  --serif: "Source Serif 4", Georgia, "Times New Roman", serif;
  --sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--sans);
  color: var(--ink);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

.container { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }

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

/* ===== Header / nav ===== */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255,255,255,0.92);
  backdrop-filter: saturate(180%) blur(8px);
  border-bottom: 1px solid var(--line);
}
.nav-wrap { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.brand { font-family: var(--serif); font-size: 1.25rem; font-weight: 600; color: var(--ink); }
.brand span { color: var(--muted); font-weight: 400; }
.nav { display: flex; gap: 22px; align-items: center; }
.nav a { color: var(--muted); font-size: 0.94rem; font-weight: 500; }
.nav a:hover { color: var(--accent); text-decoration: none; }
.nav-cv {
  border: 1px solid var(--accent); color: var(--accent) !important;
  padding: 5px 14px; border-radius: 6px;
}
.nav-cv:hover { background: var(--accent); color: #fff !important; }

/* ===== Hero ===== */
.hero {
  padding: 72px 24px 56px;
}
.hero-text h1 { font-family: var(--serif); font-size: 2.5rem; line-height: 1.1; margin: 0 0 6px; }
.role { font-size: 1.15rem; font-weight: 600; color: var(--accent); margin: 0 0 4px; }
.affil { color: var(--muted); margin: 0 0 20px; }
.lede { font-size: 1.06rem; margin: 0 0 24px; max-width: 60ch; }
.links { display: flex; flex-wrap: wrap; gap: 12px; }
.btn {
  display: inline-block; padding: 9px 18px; border-radius: 7px;
  background: var(--accent); color: #fff !important; font-weight: 500; font-size: 0.95rem;
}
.btn:hover { background: #163a5c; text-decoration: none; }

/* ===== Sections ===== */
.section { padding: 52px 24px; border-top: 1px solid var(--line); }
.section h2 {
  font-family: var(--serif); font-size: 1.9rem; margin: 0 0 14px;
  position: relative; padding-bottom: 10px;
}
.section h2::after {
  content: ""; position: absolute; left: 0; bottom: 0;
  width: 54px; height: 3px; background: var(--accent); border-radius: 2px;
}
.section-intro { color: var(--muted); max-width: 70ch; font-size: 1.04rem; margin: 0 0 28px; }

/* ===== Research cards ===== */
.cards { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; }
.card {
  background: var(--bg-soft); border: 1px solid var(--line);
  border-radius: 10px; padding: 22px 22px;
}
.card h3 { font-family: var(--serif); margin: 0 0 8px; font-size: 1.2rem; color: var(--accent); }
.card p { margin: 0; color: #3a4250; font-size: 0.97rem; }

/* ===== Publications ===== */
.pub-group {
  font-family: var(--serif); font-size: 1.3rem; margin: 34px 0 16px;
  padding-bottom: 8px; border-bottom: 1px solid var(--line);
}
.pub-list { list-style: none; margin: 0; padding: 0; counter-reset: pub; }
.pub {
  display: grid; grid-template-columns: 64px 1fr; gap: 16px;
  padding: 16px 0; border-bottom: 1px solid var(--line);
}
.pub-year {
  font-variant-numeric: tabular-nums; font-weight: 600; color: var(--accent);
  font-size: 0.95rem; padding-top: 1px;
}
.pub-body { font-size: 0.98rem; }
.pub-authors { color: #3a4250; }
.pub-authors strong { color: var(--ink); }
.pub-title { display: block; font-family: var(--serif); font-size: 1.06rem; margin: 2px 0 1px; }
.pub-venue { color: var(--muted); font-style: italic; }
a.pdf {
  font-size: 0.82rem; font-weight: 600; margin-left: 6px;
  padding: 1px 7px; border: 1px solid var(--accent); border-radius: 4px;
  white-space: nowrap;
}
a.pdf:hover { background: var(--accent); color: #fff; text-decoration: none; }

/* ===== Contact ===== */
.contact-list { list-style: none; margin: 0; padding: 0; }
.contact-list li {
  display: grid; grid-template-columns: 110px 1fr; gap: 16px;
  padding: 12px 0; border-bottom: 1px solid var(--line); align-items: baseline;
}
.contact-list span { color: var(--muted); font-weight: 600; font-size: 0.9rem; }

/* ===== Footer ===== */
.site-footer { border-top: 1px solid var(--line); padding: 28px 0; margin-top: 24px; }
.site-footer p { margin: 0; color: var(--muted); font-size: 0.9rem; text-align: center; }

/* ===== Responsive ===== */
@media (max-width: 720px) {
  .hero { padding-top: 44px; }
  .hero-text h1 { font-size: 2rem; }
  .cards { grid-template-columns: 1fr; }
  .nav { gap: 14px; }
  .nav a:not(.nav-cv) { display: none; }   /* keep header clean on mobile */
  .pub { grid-template-columns: 48px 1fr; gap: 10px; }
  .contact-list li { grid-template-columns: 1fr; gap: 2px; }
}