/* Distill-style base: typography, reading column, sidenotes, figures, title block.
   A hand-built homage to the distill.pub template (no web components). */

:root {
  --text: rgba(0, 0, 0, 0.82);
  --text-strong: #0a0a0a;
  --muted: #6b6b6b;
  --faint: #9aa0a6;
  --bg: #ffffff;
  --bg-alt: #fafafa;
  --rule: #ececec;
  --rule-strong: #d7d7d7;
  --link: #1c6fb3;
  --link-hover: #0d4f87;

  /* Two-track accent system (used throughout for Track A vs Track B). */
  --track-a: #6d28d9; /* abstract / tokenized */
  --track-a-soft: #f1ecfe;
  --track-a-line: #d9ccf8;
  --track-b: #0f766e; /* natural-language symbolic */
  --track-b-soft: #e3f4f1;
  --track-b-line: #bfe4dd;

  /* Canonical token-role colors, used consistently across every figure:
     input = slate, reasoning (intermediate thoughts) = violet, output (answer) = teal. */
  --tok-input: #475569;        --tok-input-fill: #94a3b8;  --tok-input-soft: #eef2f6;  --tok-input-line: #cbd5e1;
  --tok-reason: #6d28d9;       --tok-reason-fill: #8b5cf6; --tok-reason-soft: #f1ecfe; --tok-reason-line: #d9ccf8;
  --tok-output: #0f766e;       --tok-output-fill: #14b8a6; --tok-output-soft: #e3f4f1; --tok-output-line: #99e0d3;

  --serif: "Source Serif 4", Georgia, "Times New Roman", serif;
  --sans: "Libre Franklin", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;

  --col-body: 680px;
  --col-margin: 240px;
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--serif);
  font-size: 18px;
  line-height: 1.7;
  font-feature-settings: "kern" 1, "liga" 1;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* ---------- Layout grid ---------- */
.d-article {
  display: grid;
  grid-template-columns:
    [screen-start] minmax(1.2rem, 1fr)
    [body-start] minmax(0, var(--col-body))
    [body-end margin-start] minmax(0, var(--col-margin))
    [margin-end] minmax(1.2rem, 1fr) [screen-end];
  column-gap: 28px;
  padding: 0 0 6rem;
}
.d-article > * { grid-column: body; }
.d-article > aside { grid-column: margin; }
.d-article > figure,
.d-article > .wide { grid-column: body-start / margin-end; }
.d-article > .full-width { grid-column: screen-start / screen-end; }

/* ---------- Title block ---------- */
.d-title {
  grid-column: body-start / margin-end;
  padding: 4.5rem 0 1.5rem;
  border-bottom: 1px solid var(--rule);
  margin-bottom: 2.5rem;
}
.d-title h1 {
  font-family: var(--sans);
  font-weight: 700;
  font-size: 2.7rem;
  line-height: 1.12;
  letter-spacing: -0.02em;
  color: var(--text-strong);
  margin: 0 0 0.6rem;
}
.d-title .subtitle {
  font-family: var(--sans);
  font-weight: 400;
  font-size: 1.3rem;
  line-height: 1.35;
  color: var(--muted);
  margin: 0 0 1.8rem;
  max-width: 40ch;
}
.byline {
  display: flex;
  flex-wrap: wrap;
  gap: 1.6rem 2.4rem;
  font-family: var(--sans);
  font-size: 0.82rem;
  margin-bottom: 1.4rem;
}
.byline .label {
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-size: 0.66rem;
  color: var(--faint);
  display: block;
  margin-bottom: 0.25rem;
}
.byline .value { color: var(--text); line-height: 1.4; }
.link-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-top: 0.4rem;
}
.link-row a {
  font-family: var(--sans);
  font-size: 0.82rem;
  text-decoration: none;
  border: 1px solid var(--rule-strong);
  border-radius: 999px;
  padding: 0.32rem 0.9rem;
  color: var(--text);
  transition: background 0.15s, border-color 0.15s;
}
.link-row a:hover { background: var(--bg-alt); border-color: var(--faint); }

/* ---------- Headings ---------- */
h2, h3, h4 {
  font-family: var(--sans);
  color: var(--text-strong);
  line-height: 1.25;
  letter-spacing: -0.01em;
}
h2 {
  font-size: 1.6rem;
  font-weight: 700;
  margin: 3.2rem 0 0.4rem;
  padding-top: 1.6rem;
  border-top: 1px solid var(--rule);
}
h3 { font-size: 1.18rem; font-weight: 600; margin: 2.2rem 0 0.3rem; }
h4 { font-size: 1rem; font-weight: 600; margin: 1.6rem 0 0.2rem; text-transform: none; }
.section-number {
  font-family: var(--sans);
  color: var(--faint);
  font-weight: 600;
  margin-right: 0.5rem;
}

/* ---------- Body text ---------- */
/* Avoid typographic widows/orphans (short last lines ending in one or two words). */
p, li, figcaption, aside, .subtitle, .lead, td, .bib { text-wrap: pretty; }
h1, h2, h3, h4, .widget-title { text-wrap: balance; }
p { margin: 1.1rem 0; }
a { color: var(--link); text-decoration: none; border-bottom: 1px solid rgba(28, 111, 179, 0.3); }
a:hover { color: var(--link-hover); border-bottom-color: var(--link-hover); }
strong { color: var(--text-strong); font-weight: 600; }
em { font-style: italic; }
hr { border: none; border-top: 1px solid var(--rule); margin: 2.5rem 0; }

ul, ol { padding-left: 1.3rem; }
li { margin: 0.4rem 0; }

.lead {
  font-size: 1.18rem;
  line-height: 1.6;
  color: var(--text);
}

/* ---------- Inline + block code ---------- */
code {
  font-family: var(--mono);
  font-size: 0.82em;
  background: var(--bg-alt);
  border: 1px solid var(--rule);
  border-radius: 4px;
  padding: 0.08em 0.35em;
}
pre {
  font-family: var(--mono);
  font-size: 0.8rem;
  line-height: 1.55;
  background: #0f1117;
  color: #e6e6e6;
  border-radius: 8px;
  padding: 1rem 1.1rem;
  overflow-x: auto;
}
pre code { background: none; border: none; padding: 0; color: inherit; font-size: inherit; }
/* Syntax-highlighted (§5) blocks: Prism's theme forces font-size:1em (~18px);
   keep them small and dense like the rest of the code. */
pre[class*="language-"],
pre[class*="language-"] code,
code[class*="language-"] { font-size: 0.72rem; line-height: 1.5; }
pre[class*="language-"] { background: #0f1117; padding: 0.95rem 1.1rem; }

/* ---------- Sidenotes ---------- */
aside {
  font-family: var(--sans);
  font-size: 0.78rem;
  line-height: 1.45;
  color: var(--muted);
  align-self: start;
  padding-top: 0.2rem;
  border-left: 2px solid var(--rule-strong);
  padding-left: 0.8rem;
}
aside .sidenote-num { color: var(--link); font-weight: 600; }

/* ---------- Figures ---------- */
figure { margin: 2.2rem 0; }
figcaption {
  font-family: var(--sans);
  font-size: 0.8rem;
  line-height: 1.5;
  color: var(--muted);
  margin-top: 0.8rem;
}
figcaption b { color: var(--text); font-weight: 600; }
figure img { max-width: 100%; height: auto; border-radius: 8px; display: block; }
.hero { margin: 0.5rem 0 1rem; }
.hero img { width: 100%; border-radius: 10px; border: 1px solid var(--rule); }

/* ---------- Tables ---------- */
table { border-collapse: collapse; width: 100%; font-size: 0.92rem; margin: 1.2rem 0; }
th, td { text-align: left; padding: 0.5rem 0.7rem; border-bottom: 1px solid var(--rule); }
th { font-family: var(--sans); font-size: 0.74rem; text-transform: uppercase; letter-spacing: 0.05em; color: var(--muted); }
.compare-table td:first-child { font-family: var(--sans); font-size: 0.8rem; color: var(--muted); width: 24%; }

/* ---------- Footer / bibliography ---------- */
.appendix { margin-top: 3rem; }
.appendix h2 { font-size: 1.15rem; }
.bib { font-size: 0.82rem; color: var(--muted); }
.bib pre { background: var(--bg-alt); color: var(--text); border: 1px solid var(--rule); }

/* ---------- KaTeX sizing ---------- */
.katex { font-size: 1em; }
.katex-display { margin: 1.2rem 0; overflow-x: auto; overflow-y: hidden; }

/* ---------- Responsive ---------- */
@media (max-width: 1080px) {
  .d-article {
    grid-template-columns: [screen-start] minmax(1rem, 1fr) [body-start] minmax(0, var(--col-body)) [body-end margin-end] minmax(1rem, 1fr) [screen-end];
  }
  .d-article > aside {
    grid-column: body;
    border-left: 3px solid var(--rule-strong);
    background: var(--bg-alt);
    border-radius: 0 6px 6px 0;
    padding: 0.7rem 0.9rem;
    margin: 1rem 0;
  }
  .d-article > figure,
  .d-article > .wide { grid-column: body; }
}
@media (max-width: 640px) {
  body { font-size: 16px; }
  .d-title { padding-top: 2.6rem; }
  .d-title h1 { font-size: 2rem; }
  .d-title .subtitle { font-size: 1.1rem; }
}