/* ===== Design tokens ===== */
:root {
  --bg: #fbfbf9;
  --surface: #ffffff;
  --text: #1c1c1a;
  --text-soft: #55534d;
  --muted: #8a887f;
  --border: #e6e3db;
  --accent: #2f7ea6;        /* powder / sky blue */
  --accent-soft: #4a97bd;
  --maxw: 720px;
  --serif: "Newsreader", Georgia, "Times New Roman", serif;
  --sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #161614;
    --surface: #1e1e1b;
    --text: #ededea;
    --text-soft: #b9b6ae;
    --muted: #86847c;
    --border: #2e2e2a;
    --accent: #86c5e0;
    --accent-soft: #a3d4ea;
  }
}

/* ===== Base ===== */
* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 72px; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--serif);
  font-size: 19px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
  text-decoration: none;
  text-underline-offset: 2px;
}
a:hover { text-decoration: underline; }

/* ===== Header / nav ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(1.4) blur(8px);
  border-bottom: 1px solid var(--border);
}
.nav {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 14px 24px;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
}
.nav-brand {
  font-family: var(--sans);
  font-weight: 600;
  font-size: 16px;
  color: var(--text);
  letter-spacing: -0.01em;
}
.nav-links {
  display: flex;
  gap: 22px;
  list-style: none;
  margin: 0;
  padding: 0;
  font-family: var(--sans);
  font-size: 14.5px;
}
.nav-links a { color: var(--text-soft); }
.nav-links a:hover { color: var(--accent); text-decoration: none; }

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

.section {
  padding: 46px 0;
  border-top: 1px solid var(--border);
}
h2 {
  font-family: var(--sans);
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 22px;
}
.subhead {
  font-family: var(--sans);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--text-soft);
  margin: 34px 0 14px;
}

/* ===== Intro ===== */
.intro { padding: 54px 0 40px; }
.intro-grid {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 30px;
  align-items: start;
}
.intro-photo img {
  width: 140px;
  height: 140px;
  object-fit: cover;
  border-radius: 6px;
  border: 1px solid var(--border);
}
.intro-text h1 {
  font-size: 40px;
  line-height: 1.1;
  font-weight: 600;
  letter-spacing: -0.02em;
  margin: 0 0 8px;
}
.tagline {
  font-family: var(--sans);
  font-size: 16px;
  color: var(--text-soft);
  margin: 0 0 18px;
}
.bio { margin: 0 0 18px; color: var(--text); }
.intro-links {
  font-family: var(--sans);
  font-size: 15px;
  margin: 0;
}
.dot { color: var(--muted); margin: 0 8px; }

/* ===== Papers ===== */
.paper { margin: 0 0 26px; }
.paper-list { list-style: none; margin: 0; padding: 0; counter-reset: paper; }
.paper-list > li { margin: 0 0 26px; }
.paper-title {
  font-size: 21px;
  font-weight: 600;
  line-height: 1.3;
  margin: 0 0 4px;
}
.jmp .paper-title { font-size: 23px; }
.paper-meta {
  font-family: var(--sans);
  font-size: 14.5px;
  color: var(--text-soft);
  margin: 0 0 10px;
}
.paper-abstract {
  font-size: 17.5px;
  line-height: 1.6;
  color: var(--text-soft);
  margin: 0 0 10px;
}
.paper-links {
  font-family: var(--sans);
  font-size: 14.5px;
  margin: 0;
}
.muted-link { font-family: var(--sans); font-size: 14.5px; color: var(--muted); }
.wip-list { margin: 0; padding-left: 20px; color: var(--text-soft); }
.wip-list li { margin: 0 0 6px; }

/* ===== Teaching ===== */
.section-lead { color: var(--text-soft); margin: 0 0 20px; }
.teaching-list { list-style: none; margin: 0; padding: 0; }
.teaching-item {
  display: grid;
  grid-template-columns: 130px 1fr;
  gap: 18px;
  padding: 14px 0;
  border-bottom: 1px solid var(--border);
}
.teaching-item:last-child { border-bottom: none; }
.teaching-role {
  font-family: var(--sans);
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--accent);
  padding-top: 2px;
}
.teaching-body { display: flex; flex-direction: column; }
.course { font-weight: 500; }
.teaching-meta {
  font-family: var(--sans);
  font-size: 14px;
  color: var(--muted);
}

/* ===== Buttons ===== */
.button {
  display: inline-block;
  font-family: var(--sans);
  font-size: 15px;
  font-weight: 500;
  padding: 9px 18px;
  border: 1px solid var(--accent);
  border-radius: 6px;
  color: var(--accent);
}
.button:hover { background: var(--accent); color: #fff; text-decoration: none; }

/* ===== Contact ===== */
.contact-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.contact-label {
  font-family: var(--sans);
  font-size: 12.5px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  margin: 0 0 4px;
}
.contact-grid p { margin: 0 0 4px; font-size: 17px; }
.references { margin-top: 26px; }

/* ===== Footer ===== */
.site-footer {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 30px 24px 50px;
  border-top: 1px solid var(--border);
  font-family: var(--sans);
  font-size: 13.5px;
  color: var(--muted);
}

/* ===== Responsive ===== */
@media (max-width: 620px) {
  body { font-size: 18px; }
  .nav-links { gap: 16px; }
  .intro-grid { grid-template-columns: 1fr; gap: 20px; }
  .intro-photo img { width: 110px; height: 110px; }
  .intro-text h1 { font-size: 32px; }
  .contact-grid { grid-template-columns: 1fr; }
  .teaching-item { grid-template-columns: 1fr; gap: 4px; }
}