/* Collatz finite-block diagnostic study — shared paper stylesheet.
   Deliberately restrained: academic register, hairline rules, one signature
   element (the epistemic-stance callouts) that encodes the paper's thesis. */

:root {
  --ink: #1a1a1a;
  --muted: #555;
  --rule: #d8d4cc;
  --rule-strong: #1a1a1a;
  --bg: #fbfaf7;
  --panel: #f3f0e9;
  --accent: #5b6b8c;      /* "consistent with" — neutral candidate */
  --accent-warn: #9a6a3a; /* "does not establish" — restraint */
  --mono: "SFMono-Regular", "JetBrains Mono", Consolas, "Liberation Mono", monospace;
  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua", Georgia, serif;
  --sans: "Inter", -apple-system, "Segoe UI", Helvetica, Arial, sans-serif;
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 18px;
  line-height: 1.62;
}

.wrap {
  max-width: 760px;
  margin: 0 auto;
  padding: 4rem 1.5rem 6rem;
}


/* Site-wide navigation */
.site-nav,
.footer-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem 1rem;
  align-items: center;
  font-family: var(--sans);
  font-size: 0.78rem;
  line-height: 1.4;
}
.site-nav {
  margin-bottom: 1.4rem;
  padding-bottom: 0.85rem;
  border-bottom: 1px solid var(--rule);
}
.footer-nav {
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--rule);
}
.site-nav a,
.footer-nav a {
  border: none;
  color: var(--muted);
}
.site-nav a:hover,
.footer-nav a:hover,
.site-nav a[aria-current="page"],
.footer-nav a[aria-current="page"] {
  color: var(--ink);
}
.site-nav a[aria-current="page"],
.footer-nav a[aria-current="page"] {
  font-weight: 650;
}

/* Running header: chapter number + short series mark */
.chapter-mark {
  font-family: var(--sans);
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
  border-bottom: 1px solid var(--rule);
  padding-bottom: 0.75rem;
  margin-bottom: 2.5rem;
  display: flex;
  justify-content: space-between;
  gap: 1rem;
}
.chapter-mark .num { color: var(--ink); font-weight: 600; }

h1 {
  font-family: var(--sans);
  font-weight: 650;
  font-size: 2rem;
  line-height: 1.15;
  letter-spacing: -0.01em;
  margin: 0 0 1.4rem;
}
h2 {
  font-family: var(--sans);
  font-weight: 600;
  font-size: 1.3rem;
  margin: 2.8rem 0 0.9rem;
  letter-spacing: -0.005em;
}
h3 {
  font-family: var(--sans);
  font-weight: 600;
  font-size: 1.05rem;
  margin: 2rem 0 0.6rem;
}

p { margin: 0 0 1.1rem; }
.lead { font-size: 1.12rem; color: #2c2c2c; }

a { color: var(--accent); text-decoration: none; border-bottom: 1px solid var(--rule); }
a:hover { border-color: var(--accent); }

code { font-family: var(--mono); font-size: 0.86em; background: var(--panel); padding: 0.08em 0.35em; border-radius: 2px; }
pre { font-family: var(--mono); font-size: 0.82rem; line-height: 1.5; background: var(--panel); border: 1px solid var(--rule); border-radius: 3px; padding: 1rem 1.1rem; overflow-x: auto; }
pre code { background: none; padding: 0; }

ul, ol { margin: 0 0 1.2rem; padding-left: 1.3rem; }
li { margin: 0.35rem 0; }

/* Tables: hairline, data-forward */
table { border-collapse: collapse; width: 100%; margin: 1.4rem 0; font-family: var(--sans); font-size: 0.9rem; }
caption { caption-side: top; text-align: left; font-family: var(--sans); font-size: 0.8rem; color: var(--muted); margin-bottom: 0.5rem; letter-spacing: 0.02em; }
th, td { padding: 0.5rem 0.7rem; text-align: right; border-bottom: 1px solid var(--rule); }
th:first-child, td:first-child { text-align: left; }
thead th { border-bottom: 2px solid var(--rule-strong); font-weight: 600; }
tbody tr:last-child td { border-bottom: 1px solid var(--rule-strong); }
td.num, th.num { font-variant-numeric: tabular-nums; }

/* Figures */
figure { margin: 2rem 0; }
figure img { width: 100%; height: auto; border: 1px solid var(--rule); border-radius: 3px; background: #fff; }
figcaption { font-family: var(--sans); font-size: 0.82rem; color: var(--muted); margin-top: 0.6rem; }
figcaption .fignum { color: var(--ink); font-weight: 600; }

/* Signature element: epistemic-stance callouts.
   The whole paper's thesis is "what we will and will not claim", so the
   register markers get the one piece of visual emphasis. */
.stance {
  font-family: var(--sans);
  font-size: 0.92rem;
  line-height: 1.5;
  padding: 0.9rem 1.1rem 0.9rem 1.3rem;
  margin: 1.8rem 0;
  background: #fff;
  border: 1px solid var(--rule);
  border-left: 3px solid var(--accent);
  border-radius: 2px;
}
.stance .tag {
  display: block;
  font-size: 0.68rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.4rem;
  font-weight: 650;
}
.stance.warn { border-left-color: var(--accent-warn); }
.stance.warn .tag { color: var(--accent-warn); }

/* Classification chip */
.chip {
  display: inline-block;
  font-family: var(--sans);
  font-size: 0.74rem;
  font-weight: 650;
  letter-spacing: 0.04em;
  padding: 0.12rem 0.5rem;
  border-radius: 2px;
  border: 1px solid var(--rule-strong);
}
.chip.b { background: #eef1f6; }
.chip.c { background: #f6efe6; }

/* Footer nav between chapters */
.chap-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 4rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--rule);
  font-family: var(--sans);
  font-size: 0.85rem;
}
.chap-nav a { border: none; }
.chap-nav .spacer { flex: 1; }

hr { border: none; border-top: 1px solid var(--rule); margin: 2.5rem 0; }

.small { font-size: 0.85rem; color: var(--muted); }
.term { font-style: italic; }

@media (max-width: 600px) {
  body { font-size: 17px; }
  .wrap { padding: 2.5rem 1.1rem 4rem; }
  h1 { font-size: 1.6rem; }
}