/* Weight-Space Geometry — printed-broadsheet theme.
   Flat. No gradients, no shadows, no rounded glass. Ink on paper. */
:root {
  --paper: #f3efe4;
  --paper-2: #ece6d6;
  --ink: #211d18;
  --ink-soft: #50473c;
  --ink-faint: #897e6c;
  --rule: #1f1b16;          /* hairline rules are real ink, not gray */
  --rule-soft: #c9c0ab;
  --accent: #b23a23;        /* one brick-red, used sparingly */
  --maxcol: 680px;
  --display: "Fraunces", Georgia, serif;
  --body: "Newsreader", Georgia, serif;
  --mono: "IBM Plex Mono", ui-monospace, monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--body);
  font-size: 20px;
  line-height: 1.6;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
.skip { position: absolute; left: -999px; }
.skip:focus { left: 1rem; top: 1rem; background: var(--ink); color: var(--paper); padding: .5rem 1rem; z-index: 99; }

main {
  max-width: var(--maxcol);
  margin: 0 auto;
  padding: 0 28px 9rem;
  counter-reset: fig sec;
}

/* ---------- hero ---------- */
.hero { padding: 6rem 0 0; }
.venue {
  font-family: var(--mono); font-size: .7rem; font-weight: 500; letter-spacing: .14em;
  text-transform: uppercase; color: var(--accent); margin-bottom: 2rem;
}
.venue::before { content: "▩ "; }
h1 {
  font-family: var(--display);
  font-optical-sizing: auto;
  font-weight: 600;
  font-size: clamp(2.4rem, 7vw, 4rem);
  line-height: 1.02;
  letter-spacing: -.015em;
  margin: 0 0 1.4rem;
  text-wrap: balance;
}
.lede {
  font-family: var(--body); font-size: 1.28rem; font-style: italic; line-height: 1.4;
  color: var(--ink-soft); margin: 0 0 2rem; max-width: 30ch;
}
.byline {
  font-family: var(--mono); font-size: .76rem; letter-spacing: .02em; color: var(--ink-faint);
  padding-top: 1.6rem; border-top: 2px solid var(--rule);
}
.hero { border-bottom: none; }

a { color: var(--ink); text-decoration: none; box-shadow: inset 0 -1px 0 var(--accent); }
a:hover { background: var(--accent); color: var(--paper); box-shadow: none; }

/* ---------- sections ---------- */
section { margin: 4.5rem 0 0; scroll-margin-top: 2rem; }
section + section { margin-top: 5rem; }
h2 {
  font-family: var(--display); font-weight: 600; font-size: 1.9rem; letter-spacing: -.01em;
  line-height: 1.12; margin: 0 0 1.2rem; position: relative;
}
section:not(.aside) h2 { counter-increment: sec; }
section:not(.aside) h2::before {
  content: counter(sec, decimal-leading-zero);
  font-family: var(--mono); font-size: .72rem; font-weight: 500; color: var(--accent);
  position: absolute; left: -2.7rem; top: .55rem; letter-spacing: .05em;
}
@media (max-width: 1180px) { section:not(.aside) h2::before { position: static; display: inline-block; margin-right: .8rem; } }
p { margin: 0 0 1.3rem; }
section > p { max-width: 62ch; }
em { font-style: italic; }
strong { font-weight: 600; }
.aside h2 { font-size: 1rem; font-family: var(--mono); font-weight: 500; text-transform: uppercase; letter-spacing: .12em; color: var(--ink-faint); margin-bottom: 1rem; }

/* glossary plate (definition list) */
.note { border: 1.5px solid var(--rule); padding: 4px 24px; margin: 1.8rem 0 1rem; }
dl.glossary { margin: 0; }
dl.glossary > div { display: grid; grid-template-columns: 168px 1fr; gap: 5px 30px; padding: 17px 0; border-top: 1px solid var(--rule-soft); }
dl.glossary > div:first-child { border-top: 0; }
dl.glossary dt { font-family: var(--mono); font-size: .82rem; font-weight: 500; color: var(--ink); line-height: 1.3; }
dl.glossary dt span { display: block; font-size: .62rem; letter-spacing: .08em; text-transform: uppercase; color: var(--accent); margin-top: 5px; }
dl.glossary dd { margin: 0; font-family: var(--body); font-size: 1rem; line-height: 1.45; color: var(--ink-soft); }
dl.glossary dd b { color: var(--ink); font-weight: 600; }
@media (max-width: 620px) { dl.glossary > div { grid-template-columns: 1fr; gap: 6px; } }

/* objectives (formulas) */
.block-label { font-family: var(--mono); font-size: .66rem; letter-spacing: .12em; text-transform: uppercase; color: var(--ink-faint); margin: 2.2rem 0 0; }
dl.objectives > div { grid-template-columns: 130px 1fr; align-items: center; }
dl.objectives dt { display: flex; align-items: center; }
dl.objectives dt .swatch { display: inline-block; width: 9px; height: 9px; margin-right: 8px; flex: none; }
dl.objectives dd { color: var(--ink); overflow-x: auto; overflow-y: hidden; padding: 2px 0; }
dl.objectives dd .katex { font-size: 1.04em; }
.footnote { font-family: var(--body); font-size: .92rem; font-style: italic; line-height: 1.5; color: var(--ink-soft); margin: 1rem 0 0; max-width: 64ch; }
.footnote strong { font-style: normal; font-weight: 600; color: var(--ink); }
.footnote .katex { font-size: .96em; font-style: normal; }
.dropcap::first-letter {
  font-family: var(--display); font-weight: 600; float: left; font-size: 4.4rem;
  line-height: .76; padding: .06em .1em 0 0; color: var(--ink);
}

/* ---------- figures: framed plates, hairline rule, numbered ---------- */
figure.wide {
  counter-increment: fig;
  margin: 2.4rem 0 1rem;
  width: min(940px, calc(100vw - 56px));
  margin-left: 50%; transform: translateX(-50%);
  background: var(--paper);
  border: 1.5px solid var(--rule);
  border-radius: 0;
  padding: 18px 22px 16px;
}
figure.wide::before {
  content: "Fig. " counter(fig, decimal-leading-zero);
  display: block;
  font-family: var(--mono); font-size: .68rem; font-weight: 500; letter-spacing: .12em;
  text-transform: uppercase; color: var(--accent);
  padding-bottom: 12px; margin-bottom: 14px; border-bottom: 1px solid var(--rule-soft);
}
#methods figure.wide::before { content: "Table 01"; }
figcaption {
  font-family: var(--body); font-size: .92rem; font-style: italic; line-height: 1.45;
  color: var(--ink-soft); margin-top: 14px; padding-top: 12px; border-top: 1px solid var(--rule-soft);
}
.plot { width: 100%; height: 440px; }
.plot.square { height: 520px; }
@media (max-width: 640px) { .plot { height: 360px; } .plot.square { height: 380px; } }

/* ---------- controls ---------- */
.controls { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 16px; margin-bottom: 16px; }
.hint { font-family: var(--mono); font-size: .68rem; color: var(--ink-faint); letter-spacing: .02em; }

/* segmented control -> editorial tab/underline */
.seg { display: inline-flex; gap: 20px; }
.seg-btn {
  font-family: var(--mono); font-size: .74rem; letter-spacing: .02em; cursor: pointer;
  border: 0; background: transparent; color: var(--ink-faint);
  padding: 4px 0 5px; border-bottom: 2px solid transparent; text-transform: uppercase;
}
.seg-btn:hover { color: var(--ink-soft); }
.seg-btn.active { color: var(--ink); border-bottom-color: var(--accent); }

/* pair toggles -> flat square chips */
.legend-toggles { display: flex; flex-wrap: wrap; gap: 6px; }
.chip {
  font-family: var(--mono); font-size: .7rem; letter-spacing: .01em; cursor: pointer; user-select: none;
  display: inline-flex; align-items: center; gap: 7px;
  padding: 4px 9px; border-radius: 0;
  border: 1px solid var(--rule-soft); background: transparent; color: var(--ink-faint);
}
.chip .dot { width: 9px; height: 9px; border-radius: 0; background: currentColor; opacity: .3; flex: none; }
.chip:hover { border-color: var(--ink-soft); color: var(--ink-soft); }
.chip.on { color: var(--ink); border-color: var(--swatch, var(--accent)); border-width: 1px; background: var(--paper-2); }
.chip.on .dot { opacity: 1; background: var(--swatch, var(--accent)); }

/* slider */
.slider-row { display: flex; align-items: center; gap: 16px; margin-top: 14px; padding-top: 14px; border-top: 1px solid var(--rule-soft); }
.slider-row label { font-family: var(--mono); font-size: .7rem; text-transform: uppercase; letter-spacing: .08em; color: var(--ink-soft); }
.slider-row output { font-family: var(--mono); font-size: .74rem; color: var(--ink); white-space: nowrap; }
input[type="range"] {
  -webkit-appearance: none; appearance: none; flex: 1; height: 2px; background: var(--rule); outline: none;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none; width: 14px; height: 14px; border-radius: 0; background: var(--accent);
  cursor: pointer; border: 0; box-shadow: none;
}
input[type="range"]::-moz-range-thumb {
  width: 14px; height: 14px; border-radius: 0; background: var(--accent); cursor: pointer; border: 0;
}

/* ---------- methods table ---------- */
table.methods { width: 100%; border-collapse: collapse; font-family: var(--mono); font-size: .8rem; }
table.methods th, table.methods td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--rule-soft); }
table.methods thead th {
  font-size: .64rem; letter-spacing: .1em; text-transform: uppercase; color: var(--ink-faint);
  font-weight: 500; border-bottom: 1.5px solid var(--rule);
}
table.methods td:first-child { font-weight: 500; color: var(--ink); }
table.methods .swatch { display: inline-block; width: 9px; height: 9px; border-radius: 0; margin-right: 8px; vertical-align: baseline; }
table.methods code { font-family: var(--mono); font-size: .92em; color: var(--accent); }

/* ---------- takeaways ---------- */
ul.takeaways { list-style: none; padding: 0; margin: 0 0 2.4rem; counter-reset: take; }
ul.takeaways li {
  counter-increment: take; position: relative; padding: 0 0 1.2rem 2.6rem; margin-bottom: 1.2rem;
  border-bottom: 1px solid var(--rule-soft); font-size: 1.05rem; line-height: 1.5; max-width: 64ch;
}
ul.takeaways li:last-child { border-bottom: 0; }
ul.takeaways li::before {
  content: counter(take, decimal-leading-zero); position: absolute; left: 0; top: .2em;
  font-family: var(--mono); font-size: .8rem; color: var(--accent); font-weight: 500;
}
.repro { font-family: var(--mono); font-size: .8rem; line-height: 1.6; color: var(--ink-soft); border-left: 2px solid var(--accent); padding: 4px 0 4px 18px; max-width: 64ch; }

footer { margin-top: 5rem; padding-top: 1.6rem; border-top: 2px solid var(--rule); font-family: var(--mono); font-size: .72rem; color: var(--ink-faint); line-height: 1.6; }

/* ---------- TOC ---------- */
#toc { position: fixed; top: 0; left: 0; height: 100vh; width: 210px; padding: 6.2rem 1.4rem 2rem; overflow-y: auto; display: none; }
.toc-inner { font-family: var(--mono); }
.toc-title { font-size: .62rem; letter-spacing: .16em; text-transform: uppercase; color: var(--ink-faint); margin-bottom: 1rem; }
#toc ol { list-style: none; margin: 0; padding: 0; counter-reset: toc; }
#toc li { counter-increment: toc; }
#toc a {
  display: block; padding: 4px 0 4px 0; font-size: .72rem; color: var(--ink-faint);
  border: 0; box-shadow: none; line-height: 1.3;
}
#toc a::before { content: counter(toc, decimal-leading-zero) "  "; color: var(--rule-soft); }
#toc a:hover { color: var(--ink); background: transparent; }
#toc a.active { color: var(--ink); }
#toc a.active::before { color: var(--accent); }
@media (min-width: 1240px) { #toc { display: block; } }