/* ============================================================
   Offprint — Mao Li personal site
   Paper-white scholarly identity. Light-only by design.
   No webfonts, no external requests.
   ============================================================ */

:root {
  --paper:      #faf8f3;
  --ink:        #1c1a17;
  --ink-2:      #56524a;
  --muted:      #8a8578;
  --link:       #1a4fa0;
  --link-hover: #123a78;
  --maize:      #ffcb05;
  --rule:       #d9d4c7;
  --rule-soft:  #e7e2d6;
  --card:       #fdfcf8;

  /* thread palette — matches the internal roadmap so site + map read as one system */
  --t1: #2a78d6;  /* SPIRIT twins */
  --t2: #1baf7a;  /* simulation validity */
  --t3: #4a3aa7;  /* dissertation */
  --t4: #eb6834;  /* AI interviewer */
  --t5: #e87ba4;  /* Vec2Summ */

  --serif: "Charter", "Bitstream Charter", "Iowan Old Style", "Palatino Linotype", Georgia, serif;
  --sans:  system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --mono:  ui-monospace, "SF Mono", "Cascadia Mono", Menlo, monospace;

  --measure: 860px;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 18px;
  line-height: 1.62;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.wrap { max-width: var(--measure); margin: 0 auto; padding: 0 28px; }

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

::selection { background: var(--maize); color: var(--ink); }

/* ---------- masthead ---------- */
.masthead {
  display: flex; align-items: baseline; justify-content: space-between;
  flex-wrap: wrap; gap: 10px 24px;
  padding: 30px 0 14px;
  border-bottom: 2px solid var(--ink);
}
.masthead .name {
  font-family: var(--sans);
  font-size: 15px; font-weight: 600;
  letter-spacing: 0.22em; text-transform: uppercase;
  color: var(--ink);
}
.masthead .name a { color: inherit; }
.masthead .name a:hover { text-decoration: none; color: var(--ink); }
.masthead nav {
  font-family: var(--sans);
  font-size: 13.5px; letter-spacing: 0.02em;
  display: flex; gap: 20px;
}
.masthead nav a { color: var(--ink-2); }
.masthead nav a[aria-current="page"] { color: var(--ink); font-weight: 600; }
.masthead nav a:hover { color: var(--ink); text-decoration: none; }

/* ---------- hero ---------- */
.hero { display: grid; grid-template-columns: 1fr 210px; gap: 44px; padding: 44px 0 30px; align-items: start; }
.thesis {
  font-size: clamp(28px, 4.4vw, 37px);
  line-height: 1.22; font-weight: 500; letter-spacing: -0.011em;
  margin: 0 0 18px; text-wrap: balance;
}
.thesis .hl {
  background-image: linear-gradient(transparent 58%, var(--maize) 58%, var(--maize) 92%, transparent 92%);
  padding: 0 2px;
}
.hero .lede { font-family: var(--sans); font-size: 15.5px; line-height: 1.6; color: var(--ink-2); margin: 0; max-width: 58ch; }
.hero .lede + .lede { margin-top: 14px; }

.aside { font-family: var(--sans); font-size: 13px; line-height: 1.55; color: var(--ink-2); }
.aside .portrait {
  width: 100%; aspect-ratio: 1; object-fit: cover;
  border-radius: 3px; border: 1px solid var(--rule);
  display: block; margin-bottom: 12px; background: var(--rule-soft);
}
.aside b { color: var(--ink); display: block; font-size: 13px; margin-top: 12px; }
.aside .links { display: flex; flex-wrap: wrap; gap: 8px 14px; margin-top: 12px; }

/* ---------- section headings ---------- */
.eyebrow {
  font-family: var(--sans);
  font-size: 12px; letter-spacing: 0.17em; text-transform: uppercase;
  color: var(--muted); font-weight: 600;
  border-top: 1px solid var(--rule); padding-top: 16px;
  margin: 46px 0 18px;
}
h2.section { font-size: 25px; font-weight: 600; margin: 6px 0 16px; letter-spacing: -0.01em; }

/* ---------- research threads (home) ---------- */
.threads { display: flex; flex-direction: column; gap: 2px; }
.thread { display: grid; grid-template-columns: 46px 1fr; gap: 16px; padding: 12px 0; border-bottom: 1px solid var(--rule-soft); }
.thread:last-child { border-bottom: none; }
.thread .num { font-style: italic; font-size: 19px; color: var(--muted); padding-top: 2px; }
.thread h3 { font-size: 18.5px; font-weight: 600; margin: 0; }
.thread .tc { display: inline-block; width: 9px; height: 9px; border-radius: 50%; margin-right: 8px; vertical-align: middle; }
.thread p { font-family: var(--sans); font-size: 14px; line-height: 1.55; color: var(--ink-2); margin: 5px 0 0; }
.thread .more { font-family: var(--sans); font-size: 13px; }

/* ---------- publications ---------- */
.pubs { display: flex; flex-direction: column; }
.pub { padding: 12px 0; border-bottom: 1px dotted var(--rule); }
.pub:last-child { border-bottom: none; }
.pub .venue {
  font-family: var(--sans); font-size: 10.5px; font-weight: 700;
  letter-spacing: 0.09em; text-transform: uppercase; color: #9c6a00;
  display: inline-block; margin-right: 4px;
}
.pub .venue.preprint { color: var(--ink-2); }
.pub .title { }
.pub .authors { font-family: var(--sans); font-size: 13.5px; color: var(--ink-2); display: block; margin-top: 2px; }
.pub .authors .me { color: var(--ink); font-weight: 600; }
.pub .plinks { font-family: var(--sans); font-size: 12.5px; margin-top: 4px; display: inline-flex; gap: 12px; }
.year-head { font-family: var(--sans); font-size: 13px; font-weight: 700; color: var(--muted); letter-spacing: 0.04em; margin: 24px 0 4px; }
.subsection-note { font-family: var(--sans); font-size: 13px; color: var(--muted); margin: 4px 0 8px; }

/* ---------- footer ---------- */
footer.site {
  font-family: var(--sans); font-size: 12.5px; color: var(--muted);
  border-top: 1px solid var(--rule); margin-top: 56px; padding: 18px 0 44px;
  display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap;
}
footer.site .duke { font-style: italic; font-family: var(--serif); font-size: 13.5px; }

/* ---------- research program: thread bands ---------- */
.figcaption { font-family: var(--sans); font-size: 14.5px; line-height: 1.55; color: var(--ink-2); margin: 0 0 6px; }
.figcaption b { color: var(--ink); }

.rp-bands { margin: 6px 0 4px; }
.rp-banner {
  background: var(--ink); color: var(--paper);
  font-family: var(--serif); font-weight: 600;
  font-size: clamp(19px, 2.6vw, 24px); line-height: 1.24;
  border-radius: 8px; padding: 18px 22px; margin-bottom: 6px; text-wrap: balance;
}
.rp-band {
  display: grid; grid-template-columns: 232px 1fr; gap: 18px; align-items: center;
  padding: 15px 0; border-top: 1px solid var(--rule-soft);
}
.rp-band:first-of-type { border-top: none; }
.rp-lbl { display: flex; gap: 12px; align-items: baseline; }
.rp-num { font-family: var(--serif); font-style: italic; font-weight: 600; font-size: 27px; line-height: 1; flex: none; }
.rp-nm { font-size: 16px; font-weight: 600; color: var(--ink); line-height: 1.22; }
.rp-chips { display: flex; flex-wrap: wrap; gap: 9px; }
.rp-chip {
  display: block; border-radius: 8px; padding: 9px 14px; min-width: 138px;
  border-left: 4px solid var(--baseline); text-decoration: none;
}
a.rp-chip { transition: transform .12s ease, box-shadow .12s ease; }
a.rp-chip:hover { transform: translateY(-1px); box-shadow: 0 3px 12px rgba(28,26,23,.12); text-decoration: none; }
.rp-chip b { display: block; font-family: var(--sans); font-size: 13.5px; font-weight: 600; color: var(--ink); line-height: 1.25; }
.rp-chip span { font-family: var(--sans); font-size: 11px; color: var(--ink-2); }
.rp-chip.prog {
  border: 1.5px dashed var(--baseline); border-left-width: 1.5px;
  color: var(--muted); font-family: var(--sans); font-size: 12.5px;
  display: flex; align-items: center; background: transparent; min-width: 0;
}
.rp-chip.wip { background: transparent; border: 1.5px dashed var(--baseline); max-width: 250px; }
.rp-chip.wip::before {
  content: "In progress"; display: block;
  font-family: var(--sans); font-size: 9.5px; font-weight: 700;
  letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); margin-bottom: 2px;
}
.rp-chip.wip b { color: var(--ink-2); }
.rp-chip.wip span { display: block; margin-top: 2px; line-height: 1.35; }

.thread-notes { margin-top: 40px; }
.thread-notes .tn { padding: 16px 0; border-top: 1px solid var(--rule-soft); display: grid; grid-template-columns: 130px 1fr; gap: 18px; }
.thread-notes .tn .lbl { font-family: var(--sans); font-size: 13px; font-weight: 700; }
.thread-notes .tn .lbl .tc { display: inline-block; width: 9px; height: 9px; border-radius: 50%; margin-right: 7px; }
.thread-notes .tn p { margin: 0; font-size: 16px; color: var(--ink-2); }

/* ---------- 404 ---------- */
.notfound { text-align: center; padding: 90px 0 120px; }
.notfound .big { font-size: 64px; font-weight: 600; margin: 0; }
.notfound p { font-family: var(--sans); color: var(--ink-2); }

/* ---------- responsive ---------- */
@media (max-width: 720px) {
  body { font-size: 17px; }
  .hero { grid-template-columns: 1fr; gap: 26px; }
  .aside { order: -1; display: grid; grid-template-columns: 96px 1fr; gap: 16px; align-items: center; }
  .aside .portrait { margin-bottom: 0; }
  .thread-notes .tn { grid-template-columns: 1fr; gap: 6px; }
  .rp-band { grid-template-columns: 1fr; gap: 8px; align-items: start; }
  .masthead { padding-top: 22px; }
}

@media (prefers-reduced-motion: reduce) {
  a.rp-chip { transition: none; }
}