:root {
  --bg: #ffffff;
  --bg-card: #ffffff;
  --ink: #1a1a1a;
  --ink-soft: #3a3a3a;
  --ink-muted: #6e6e6e;
  --rule: #e5e5e5;
  --rule-soft: #f3f3f3;
  --accent: #6b1d1d;
  --accent-soft: #8a3a3a;
  --link: #6b1d1d;
  --link-hover: #a83232;
  --def-bg: #f7f7f7;
  --def-border: #6b1d1d;
  --thm-bg: #f4f6f9;
  --thm-border: #2c4a6b;

  --serif: "Crimson Pro", "Source Serif Pro", "Iowan Old Style", Georgia, "Times New Roman", serif;
  --sans:  "Inter", -apple-system, BlinkMacSystemFont, "Helvetica Neue", Arial, sans-serif;
  --mono:  "JetBrains Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 19px;
  line-height: 1.65;
  font-feature-settings: "kern", "liga", "onum";
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

::selection { background: #f0e5d2; color: var(--ink); }

/* ============== Masthead ============== */
.masthead {
  background: var(--bg);
  border-bottom: 1px solid var(--rule);
  padding: 88px 24px 56px;
}
.masthead-inner {
  max-width: 760px;
  margin: 0 auto;
  text-align: left;
}
.eyebrow {
  font-family: var(--sans);
  font-size: 12px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-bottom: 18px;
}
.masthead h1 {
  font-family: var(--serif);
  font-weight: 600;
  font-size: clamp(40px, 6vw, 64px);
  line-height: 1.05;
  margin: 0 0 14px;
  letter-spacing: -0.015em;
  color: var(--ink);
}
.subtitle {
  font-family: var(--serif);
  font-style: italic;
  font-size: clamp(20px, 2.4vw, 26px);
  color: var(--ink-soft);
  margin: 0 0 28px;
  line-height: 1.4;
  font-weight: 400;
}
.byline {
  font-family: var(--sans);
  font-size: 14px;
  color: var(--ink-muted);
  letter-spacing: 0.02em;
}
.byline .author { color: var(--ink-soft); font-weight: 500; }
.byline .dot { margin: 0 8px; color: var(--rule); }

/* ============== Article container ============== */
.article {
  max-width: 760px;
  margin: 0 auto;
  padding: 56px 24px 96px;
}

.article > section + section {
  margin-top: 56px;
}

/* ============== Headings ============== */
h2, h3, h4 {
  font-family: var(--serif);
  color: var(--ink);
  letter-spacing: -0.005em;
}
h2 {
  font-size: 32px;
  font-weight: 600;
  margin: 0 0 24px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--rule);
  line-height: 1.2;
}
h3 {
  font-size: 24px;
  font-weight: 600;
  margin: 40px 0 14px;
  line-height: 1.3;
}
h4 {
  font-size: 19px;
  font-weight: 600;
  margin: 28px 0 10px;
  font-style: italic;
  color: var(--ink-soft);
}

.section-label {
  font-family: var(--sans);
  font-size: 12px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-muted);
  border-bottom: none;
  padding-bottom: 0;
  margin: 0 0 14px;
  font-weight: 600;
}

/* ============== Paragraphs & inline ============== */
p {
  margin: 0 0 16px;
  text-align: left;
  hyphens: auto;
}
strong { font-weight: 600; color: var(--ink); }
em { font-style: italic; }

a {
  color: var(--link);
  text-decoration: none;
  border-bottom: 1px solid rgba(107, 29, 29, 0.25);
  transition: border-color 0.15s, color 0.15s;
}
a:hover {
  color: var(--link-hover);
  border-bottom-color: var(--link-hover);
}

/* ============== Lists ============== */
ul, ol {
  margin: 0 0 16px;
  padding-left: 28px;
}
li { margin-bottom: 6px; }
li > ul, li > ol { margin-top: 6px; margin-bottom: 0; }

/* ============== Abstract ============== */
.abstract {
  background: var(--bg-card);
  border: 1px solid var(--rule);
  border-left: 3px solid var(--accent);
  padding: 28px 32px;
  margin-top: -24px;
  margin-bottom: 48px;
  font-size: 18px;
}
.abstract p:first-of-type { margin-top: 0; }
.abstract-list { padding-left: 24px; }
.abstract-list li { margin-bottom: 10px; }

/* ============== TOC ============== */
.toc {
  background: var(--bg-card);
  border: 1px solid var(--rule);
  padding: 24px 32px;
  margin: 0 0 56px;
  font-size: 16px;
}
.toc ol { padding-left: 22px; margin: 0; counter-reset: section; list-style: none; }
.toc > ol > li { counter-increment: section; margin-bottom: 4px; font-family: var(--sans); }
.toc > ol > li::before {
  content: counter(section, decimal) ". ";
  color: var(--ink-muted);
  font-variant-numeric: tabular-nums;
}
.toc ol ol {
  counter-reset: subsection;
  list-style: none;
  padding-left: 18px;
  margin-top: 4px;
}
.toc ol ol li { counter-increment: subsection; margin-bottom: 2px; font-size: 14px; }
.toc ol ol li::before {
  content: counter(section) "." counter(subsection) " ";
  color: var(--ink-muted);
  font-variant-numeric: tabular-nums;
}
.toc a {
  border-bottom: none;
  color: var(--ink-soft);
}
.toc a:hover { color: var(--accent); }

/* ============== Callouts (definitions, theorems) ============== */
.callout {
  margin: 22px 0;
  padding: 18px 22px;
  border-left: 3px solid var(--def-border);
  background: var(--def-bg);
  border-radius: 0 4px 4px 0;
}
.callout p:last-child { margin-bottom: 0; }
.callout ul, .callout ol { margin-bottom: 0; }
.callout-label {
  font-family: var(--sans);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 8px;
}
.callout.thm {
  background: var(--thm-bg);
  border-left-color: var(--thm-border);
}
.callout.thm .callout-label {
  color: var(--thm-border);
}

/* ============== Figures ============== */
figure {
  margin: 28px 0;
  text-align: center;
}
figure img {
  max-width: 100%;
  height: auto;
  border: 1px solid var(--rule);
  background: white;
  padding: 8px;
  border-radius: 2px;
}
figcaption {
  font-family: var(--sans);
  font-size: 13px;
  color: var(--ink-muted);
  margin-top: 10px;
  line-height: 1.5;
  font-style: normal;
  text-align: center;
}

/* ============== Tables ============== */
.table-wrap {
  overflow-x: auto;
  margin: 22px 0;
  border: 1px solid var(--rule);
  border-radius: 2px;
}
table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--sans);
  font-size: 14px;
  background: var(--bg-card);
}
thead th {
  background: var(--rule-soft);
  font-weight: 600;
  text-align: left;
  padding: 12px 16px;
  border-bottom: 2px solid var(--rule);
  color: var(--ink);
  letter-spacing: 0.01em;
}
tbody td {
  padding: 10px 16px;
  border-bottom: 1px solid var(--rule);
  color: var(--ink-soft);
  vertical-align: top;
}
tbody tr:last-child td { border-bottom: none; }
tbody tr:hover { background: rgba(0,0,0,0.012); }

/* ============== References ============== */
.references, .links {
  font-size: 16px;
  padding-left: 24px;
}
.references li { margin-bottom: 10px; line-height: 1.45; }
.links li { margin-bottom: 6px; }

/* ============== Math ============== */
mjx-container[display="true"] {
  margin: 14px 0 !important;
  overflow-x: auto;
  overflow-y: hidden;
}
mjx-container { font-size: 0.98em !important; }

/* ============== Footer ============== */
.page-footer {
  border-top: 1px solid var(--rule);
  padding: 32px 24px;
  background: var(--bg);
  margin-top: 64px;
}
.footer-inner {
  max-width: 760px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  font-family: var(--sans);
  font-size: 13px;
  color: var(--ink-soft);
}
.muted { color: var(--ink-muted); }

/* ============== Responsive ============== */
@media (max-width: 720px) {
  body { font-size: 17px; }
  .masthead { padding: 56px 20px 40px; }
  .article { padding: 40px 20px 64px; }
  .abstract, .toc { padding: 20px; margin-left: 0; margin-right: 0; }
  .callout { padding: 16px 18px; }
  h2 { font-size: 26px; }
  h3 { font-size: 21px; }
  .footer-inner { flex-direction: column; align-items: flex-start; gap: 4px; }
}

/* ============== Print ============== */
@media print {
  body { background: white; font-size: 11pt; }
  .masthead { padding: 24pt 0 16pt; border: none; }
  .toc, .page-footer { display: none; }
  .article { padding: 0; max-width: none; }
  figure img { border: 1px solid #ccc; }
  a { color: var(--ink); border: none; }
}