:root {
  --ink: #1a1c20;
  --ink-soft: #41454d;
  --paper: #fbfaf7;
  --paper-2: #f3f1ea;
  --line: #d9d5ca;
  --line-soft: #e7e3d9;
  --accent: #7a4b2b;        /* burnt sienna */
  --accent-soft: #b98a5e;
  --blue: #2d4a6b;
  --chip-b-bg: #e8eef3;
  --chip-b-ink: #284867;
  --chip-c-bg: #f4e7df;
  --chip-c-ink: #8a4a23;
  --warn-bg: #fbf3e9;
  --warn-line: #e3c9a8;
  --stance-bg: #f1f0ec;
  --mono: "SFMono-Regular", "Consolas", "Liberation Mono", "Menlo", monospace;
  --serif: "Hiragino Mincho ProN", "Yu Mincho", "YuMincho", "Noto Serif JP", "Georgia", serif;
  --sans: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", "Helvetica Neue", Arial, sans-serif;
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background:
    radial-gradient(circle at 1px 1px, var(--line-soft) 1px, transparent 0) 0 0 / 26px 26px,
    var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 18px;
  line-height: 1.72;
  letter-spacing: .01em;
}

.wrap {
  max-width: 760px;
  margin: 0 auto;
  padding: 0 26px 96px;
}

/* ---- navigation ---- */
.site-nav, .footer-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 2px 0;
  align-items: center;
  font-family: var(--sans);
  font-size: 13.5px;
  letter-spacing: .02em;
  padding: 18px 0 16px;
  border-bottom: 1px solid var(--line);
}
.footer-nav {
  border-bottom: none;
  border-top: 1px solid var(--line);
  margin-top: 64px;
  padding: 18px 0 4px;
}
.site-nav a, .footer-nav a {
  color: var(--ink-soft);
  text-decoration: none;
  padding: 4px 11px 4px 0;
  margin-right: 6px;
  position: relative;
}
.site-nav a:hover, .footer-nav a:hover { color: var(--accent); }
.site-nav a[aria-current="page"],
.footer-nav a[aria-current="page"] {
  color: var(--accent);
  font-weight: 700;
}

/* ---- chapter mark ---- */
.chapter-mark {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  font-family: var(--sans);
  font-size: 12.5px;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--ink-soft);
  margin: 40px 0 30px;
}
.chapter-mark .num {
  font-weight: 800;
  color: var(--accent);
  font-feature-settings: "tnum";
}

/* ---- headings ---- */
h1 {
  font-size: 33px;
  line-height: 1.28;
  font-weight: 700;
  letter-spacing: .005em;
  margin: 0 0 26px;
}
h2 {
  font-family: var(--sans);
  font-size: 20px;
  font-weight: 700;
  letter-spacing: .01em;
  margin: 52px 0 14px;
  padding-bottom: 7px;
  border-bottom: 2px solid var(--line);
}
h3 {
  font-family: var(--sans);
  font-size: 16.5px;
  font-weight: 700;
  color: var(--blue);
  margin: 30px 0 8px;
}

p { margin: 0 0 16px; }

p.lead {
  font-size: 19.5px;
  line-height: 1.7;
  color: var(--ink-soft);
  border-left: 3px solid var(--accent-soft);
  padding-left: 18px;
  margin: 0 0 30px;
}

.term {
  font-style: normal;
  font-weight: 700;
  color: var(--accent);
}
.small { font-size: 14.5px; color: var(--ink-soft); }

a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 2px; }

ul, ol { margin: 0 0 18px; padding-left: 1.3em; }
li { margin: 0 0 8px; }

blockquote {
  margin: 22px 0;
  padding: 4px 0 4px 22px;
  border-left: 3px solid var(--accent);
  color: var(--ink-soft);
  font-style: italic;
}
blockquote p { margin: 0; }

/* ---- code ---- */
code {
  font-family: var(--mono);
  font-size: .86em;
  background: var(--paper-2);
  border: 1px solid var(--line-soft);
  border-radius: 4px;
  padding: .08em .36em;
  color: var(--accent);
}
pre {
  background: #20242b;
  color: #e6e3da;
  border-radius: 8px;
  padding: 16px 18px;
  overflow-x: auto;
  font-size: 14px;
  line-height: 1.6;
  margin: 18px 0;
}
pre code {
  background: none;
  border: none;
  padding: 0;
  color: inherit;
  font-size: 1em;
}

/* ---- tables ---- */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 14px 0 22px;
  font-family: var(--sans);
  font-size: 14.5px;
}
caption {
  caption-side: top;
  text-align: left;
  font-family: var(--sans);
  font-size: 13px;
  color: var(--ink-soft);
  margin-bottom: 8px;
  line-height: 1.5;
}
th, td {
  border-bottom: 1px solid var(--line);
  padding: 8px 10px;
  text-align: left;
  vertical-align: top;
}
thead th {
  border-bottom: 2px solid var(--ink-soft);
  font-weight: 700;
  white-space: nowrap;
}
td.num, th.num { text-align: right; font-feature-settings: "tnum"; white-space: nowrap; }
tbody tr:hover { background: var(--paper-2); }

/* ---- stance boxes ---- */
.stance {
  background: var(--stance-bg);
  border: 1px solid var(--line);
  border-left: 4px solid var(--accent-soft);
  border-radius: 6px;
  padding: 16px 18px;
  margin: 22px 0;
  font-size: 16.5px;
  line-height: 1.66;
}
.stance.warn {
  background: var(--warn-bg);
  border-color: var(--warn-line);
  border-left-color: var(--accent);
}
.stance .tag {
  display: inline-block;
  font-family: var(--sans);
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--accent);
  margin-right: 8px;
  padding: 2px 8px;
  background: rgba(122, 75, 43, .09);
  border-radius: 4px;
}

/* ---- chips ---- */
.chip {
  display: inline-block;
  font-family: var(--sans);
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: .04em;
  padding: 1px 8px;
  border-radius: 999px;
  vertical-align: middle;
}
.chip.b { background: var(--chip-b-bg); color: var(--chip-b-ink); }
.chip.c { background: var(--chip-c-bg); color: var(--chip-c-ink); }

/* ---- figures ---- */
figure {
  margin: 24px 0;
  text-align: center;
}
figure img {
  max-width: 100%;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #fff;
  padding: 8px;
}
figcaption {
  font-family: var(--sans);
  font-size: 13.5px;
  color: var(--ink-soft);
  margin-top: 10px;
  text-align: left;
  line-height: 1.55;
}
.fignum { font-weight: 700; color: var(--accent); }

/* ---- chapter nav (prev/next) ---- */
.chap-nav {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-top: 56px;
  padding-top: 20px;
  border-top: 2px solid var(--line);
  font-family: var(--sans);
  font-size: 15px;
}
.chap-nav .spacer { flex: 1; }
.chap-nav a {
  text-decoration: none;
  font-weight: 600;
  padding: 6px 2px;
}
.chap-nav a:hover { color: var(--accent-soft); }

/* ---- MathJax overflow safety ---- */
mjx-container { overflow-x: auto; overflow-y: hidden; max-width: 100%; }

@media (max-width: 640px) {
  body { font-size: 16.5px; }
  .wrap { padding: 0 18px 72px; }
  h1 { font-size: 27px; }
  .chapter-mark { flex-direction: column; gap: 4px; }
}

@media (prefers-reduced-motion: reduce) {
  * { scroll-behavior: auto !important; }
}