/* Layout: a lab notebook. A 68ch reading column for story and science, broken by
   full-width lab benches (a live canvas with an instrument panel beside it). */
:root {
  --paper: #f2f4f7;        /* page */
  --sheet: #fcfcfd;        /* benches, charts, cards */
  --ink: #131a2d;          /* text */
  --ink-2: #474f67;        /* secondary text */
  --muted: #626a83;        /* labels, axis ticks */
  --rule: #dde1e9;         /* hairlines */
  --rule-strong: #c2c8d5;
  --edge: #a3abbf;         /* network links */
  --accent: #2b3f95;       /* links, focus */
  --wash: rgba(43, 63, 149, 0.07);
  --s1: #2a78d6;           /* data: blue */
  --s2: #eb6834;           /* data: orange */
  --s3: #1baf7a;           /* data: aqua */
  --code-k: #2b3f95;
  --code-s: #17694c;
  --shadow: 0 10px 30px rgba(19, 26, 45, 0.14);
  --f-display: "STIX Two Text", "STIX Two", Cambria, Georgia, serif;
  --f-ui: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --f-mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --max: 1200px;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #0d1121; --sheet: #141a2d; --ink: #e7eaf3; --ink-2: #aeb5ca; --muted: #858da6;
    --rule: #252c44; --rule-strong: #353e5b; --edge: #4f5977; --accent: #a2b3ff;
    --wash: rgba(162, 179, 255, 0.08); --s1: #3987e5; --s2: #d95926; --s3: #199e70;
    --code-k: #a2b3ff; --code-s: #7dd3ae; --shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #0d1121; --sheet: #141a2d; --ink: #e7eaf3; --ink-2: #aeb5ca; --muted: #858da6;
  --rule: #252c44; --rule-strong: #353e5b; --edge: #4f5977; --accent: #a2b3ff;
  --wash: rgba(162, 179, 255, 0.08); --s1: #3987e5; --s2: #d95926; --s3: #199e70;
  --code-k: #a2b3ff; --code-s: #7dd3ae; --shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 16px/1.5 var(--f-ui);
  -webkit-font-smoothing: antialiased;
}
body::before {
  content: ""; position: fixed; inset: 0 0 auto; height: env(safe-area-inset-top, 0px);
  z-index: 10; background: var(--paper);
}
a { color: var(--accent); text-underline-offset: 3px; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.wrap {
  max-width: var(--max);
  margin-inline: auto;
  padding-left: max(16px, env(safe-area-inset-left, 0px));
  padding-right: max(16px, env(safe-area-inset-right, 0px));
}
@media (min-width: 720px) {
  .wrap { padding-left: max(32px, env(safe-area-inset-left, 0px)); padding-right: max(32px, env(safe-area-inset-right, 0px)); }
}
.kicker {
  margin: 0; font: 600 0.6875rem/1.2 var(--f-ui); letter-spacing: 0.12em;
  text-transform: uppercase; color: var(--muted);
}
var { font-style: italic; }
sub, sup { font-size: 0.72em; line-height: 0; }

/* ---------- Header ---------- */
.site-head {
  position: sticky; top: env(safe-area-inset-top, 0px); z-index: 20;
  background: var(--paper); border-bottom: 1px solid var(--rule);
}
.head-row { display: flex; align-items: center; justify-content: space-between; gap: 16px; min-height: 58px; }
.brand {
  display: inline-flex; align-items: center; gap: 10px; color: var(--ink); text-decoration: none;
  font: italic 600 1.3rem/1 var(--f-display);
}
.brand svg { flex: none; }
.menu { position: relative; }
.menu summary {
  list-style: none; cursor: pointer; display: inline-flex; align-items: center; gap: 10px;
  font: 600 0.8125rem/1 var(--f-ui); padding: 10px 14px; border: 1px solid var(--rule-strong);
  border-radius: 8px; color: var(--ink); user-select: none;
}
.menu summary::-webkit-details-marker { display: none; }
.menu summary::after {
  content: ""; width: 6px; height: 6px; border-right: 1.5px solid currentColor;
  border-bottom: 1.5px solid currentColor; transform: translateY(-2px) rotate(45deg);
}
.menu[open] summary::after { transform: translateY(1px) rotate(-135deg); }
.menu summary:hover { border-color: var(--ink-2); }
.menu-panel {
  position: absolute; inset-inline-end: 0; top: calc(100% + 8px); width: min(400px, calc(100vw - 32px));
  max-height: calc(100vh - 90px); overflow: auto; background: var(--sheet);
  border: 1px solid var(--rule-strong); border-radius: 12px; box-shadow: var(--shadow); padding: 6px; z-index: 30;
}
.menu-panel ol { list-style: none; margin: 0; padding: 0; }
.menu-panel a {
  display: grid; grid-template-columns: 1.75rem minmax(0, 1fr); gap: 10px; padding: 10px;
  border-radius: 8px; color: var(--ink); text-decoration: none;
}
.menu-panel a:hover, .menu-panel a[aria-current="page"] { background: var(--wash); }
.menu-num { font: 500 1.15rem/1.2 var(--f-display); color: var(--muted); }
.menu-title { display: block; font: 600 0.9375rem/1.3 var(--f-ui); }
.menu-q { display: block; margin-top: 2px; font: 0.8125rem/1.4 var(--f-ui); color: var(--ink-2); }
.menu-home { display: block; padding: 10px; border-top: 1px solid var(--rule); margin-top: 4px; font: 600 0.8125rem var(--f-ui); }

/* ---------- Buttons and controls ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  font: 600 0.8125rem/1 var(--f-ui); padding: 9px 14px; border-radius: 8px;
  border: 1px solid var(--rule-strong); background: transparent; color: var(--ink);
  cursor: pointer; text-decoration: none; white-space: nowrap;
}
.btn:hover { border-color: var(--ink-2); background: var(--wash); }
.btn-primary { background: var(--ink); border-color: var(--ink); color: var(--sheet); }
.btn-primary:hover { background: var(--ink-2); border-color: var(--ink-2); }
.btn-large { padding: 13px 18px; font-size: 0.9375rem; }
.btn-small { padding: 6px 10px; font-size: 0.75rem; }
.btn:disabled { opacity: 0.5; cursor: default; }
.btn-row { display: flex; flex-wrap: wrap; gap: 8px; }

.ctl { min-width: 0; }
.ctl-row { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; margin-bottom: 4px; }
.ctl-row label { font: 0.8125rem/1.35 var(--f-ui); color: var(--ink-2); }
.ctl-value { font: 500 0.875rem var(--f-mono); color: var(--ink); font-variant-numeric: tabular-nums; }
.ctl-hint { margin: 4px 0 0; font: 0.75rem/1.4 var(--f-ui); color: var(--muted); }
input[type="range"] { -webkit-appearance: none; appearance: none; width: 100%; height: 24px; margin: 0; background: transparent; cursor: pointer; }
input[type="range"]::-webkit-slider-runnable-track {
  height: 4px; border-radius: 2px;
  background: linear-gradient(to right, var(--ink) var(--fill, 50%), var(--rule-strong) var(--fill, 50%));
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none; width: 18px; height: 18px; margin-top: -7px; border-radius: 50%;
  background: var(--sheet); border: 2px solid var(--ink); box-shadow: 0 1px 3px rgba(0, 0, 0, 0.25);
}
input[type="range"]::-moz-range-track { height: 4px; border-radius: 2px; background: var(--rule-strong); }
input[type="range"]::-moz-range-progress { height: 4px; border-radius: 2px; background: var(--ink); }
input[type="range"]::-moz-range-thumb { width: 14px; height: 14px; border-radius: 50%; background: var(--sheet); border: 2px solid var(--ink); }
input[type="range"]:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 4px; }
fieldset.ctl { border: 0; padding: 0; margin: 0; }
fieldset.ctl legend { padding: 0; margin-bottom: 6px; font: 0.8125rem/1.35 var(--f-ui); color: var(--ink-2); }
.seg { display: flex; flex-wrap: wrap; gap: 6px; }
.seg input { position: absolute; opacity: 0; width: 1px; height: 1px; pointer-events: none; }
.seg label {
  font: 500 0.8125rem/1 var(--f-ui); padding: 8px 11px; border-radius: 999px; cursor: pointer;
  border: 1px solid var(--rule-strong); color: var(--ink-2);
}
.seg label:hover { border-color: var(--ink-2); color: var(--ink); }
.seg input:checked + label { background: var(--ink); border-color: var(--ink); color: var(--sheet); }
.seg input:focus-visible + label { outline: 2px solid var(--accent); outline-offset: 2px; }
.ctl-toggle { display: flex; align-items: center; gap: 8px; font: 0.8125rem var(--f-ui); color: var(--ink-2); }
.ctl-toggle input { accent-color: var(--ink); width: 16px; height: 16px; margin: 0; }

/* ---------- Home ---------- */
.hero {
  display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); align-items: center;
  gap: clamp(24px, 5vw, 64px); padding-block: clamp(28px, 6vw, 72px) clamp(28px, 5vw, 56px);
}
.hero-text { min-width: 0; }
.hero h1 {
  margin: 14px 0 0; font: italic 500 clamp(3.25rem, 9vw, 6.75rem)/0.92 var(--f-display);
  letter-spacing: -0.02em; text-wrap: balance;
}
.hero h1:focus { outline: none; }
.lede { margin: 22px 0 28px; max-width: 34em; font: 1.25rem/1.55 var(--f-display); color: var(--ink-2); }
.hero-facts { margin: 22px 0 0; font: 0.8125rem var(--f-ui); color: var(--muted); }
.hero-visual { margin: 0; min-width: 0; }
.hero-stage { position: relative; }
.hero-counter {
  position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%);
  display: flex; flex-direction: column; align-items: center; gap: 4px; text-align: center;
  padding: 14px 18px; border-radius: 16px; pointer-events: none;
  background: color-mix(in srgb, var(--paper) 88%, transparent);
}
.counter-num { font: 600 clamp(2.75rem, 7vw, 4.5rem)/1 var(--f-ui); letter-spacing: -0.02em; color: var(--ink); }
.counter-label { max-width: 12em; font: 0.8125rem/1.35 var(--f-ui); color: var(--ink-2); }
.counter-sub { font: 0.75rem var(--f-mono); color: var(--muted); }
.hero-cap { display: flex; align-items: flex-start; justify-content: space-between; gap: 16px; margin-top: 8px; font: 0.875rem/1.5 var(--f-ui); color: var(--ink-2); }
@media (max-width: 860px) { .hero { grid-template-columns: minmax(0, 1fr); } }

.home-sec { padding-block: 44px; border-top: 1px solid var(--rule); }
.home-sec > h2 { margin: 0 0 8px; font: 600 clamp(1.75rem, 3.2vw, 2.25rem)/1.1 var(--f-display); text-wrap: balance; }
.home-intro { margin: 0 0 24px; max-width: 60ch; font: 1.1rem/1.55 var(--f-display); color: var(--ink-2); }
.toc { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--rule-strong); }
.toc a {
  display: grid; grid-template-columns: 4rem minmax(0, 1fr) minmax(0, 17rem); align-items: baseline;
  gap: 6px 24px; padding: 22px 10px; border-bottom: 1px solid var(--rule); color: inherit; text-decoration: none;
}
.toc a:hover { background: var(--wash); }
.toc a:hover .toc-num { color: var(--ink); }
.toc-num { font: 500 2.5rem/1 var(--f-display); color: var(--muted); font-variant-numeric: lining-nums; }
.toc-main { min-width: 0; }
.toc-title { display: block; font: 600 1.5rem/1.2 var(--f-display); color: var(--ink); }
.toc-q { display: block; margin-top: 4px; font: italic 1.1rem/1.45 var(--f-display); color: var(--ink-2); }
.toc-lab { font: 0.875rem/1.45 var(--f-ui); color: var(--ink-2); }
.toc-lab b { display: block; margin-bottom: 4px; font: 600 0.6875rem var(--f-ui); letter-spacing: 0.12em; text-transform: uppercase; color: var(--muted); }
@media (max-width: 760px) {
  .toc a { grid-template-columns: 2.75rem minmax(0, 1fr); padding-inline: 4px; }
  .toc-lab { grid-column: 2; }
  .toc-num { font-size: 1.8rem; }
}
.steps { list-style: none; margin: 16px 0 0; padding: 0; display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 24px; counter-reset: step; }
.steps li { counter-increment: step; display: flex; flex-direction: column; gap: 6px; border-top: 1px solid var(--rule-strong); padding-top: 14px; }
.step-title { font: 600 1.25rem/1.2 var(--f-display); }
.step-title::before { content: counter(step) ". "; color: var(--muted); }
.step-text { font: 0.9375rem/1.55 var(--f-ui); color: var(--ink-2); }
@media (max-width: 860px) { .steps { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 480px) { .steps { grid-template-columns: minmax(0, 1fr); } }
.tools { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 24px 32px; }
.tools li { border-top: 1px solid var(--rule-strong); padding-top: 12px; min-width: 0; }
.tool-head { margin: 0 0 6px; display: flex; align-items: baseline; justify-content: space-between; gap: 12px; }
.tool-head a { font: 600 1.05rem var(--f-ui); color: var(--ink); }
.tool-where { font: 0.75rem var(--f-mono); color: var(--muted); }
.tool-text { margin: 0; font: 0.9375rem/1.55 var(--f-ui); color: var(--ink-2); }
@media (max-width: 860px) { .tools { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 520px) { .tools { grid-template-columns: minmax(0, 1fr); } }
.books { list-style: none; margin: 0; padding: 0; display: grid; gap: 16px; max-width: 72ch; }
.books p { margin: 0; }
.book-title { font: 600 1.15rem/1.4 var(--f-display); }
.book-title a { color: var(--ink); }
.book-meta { font: 400 0.875rem var(--f-ui); color: var(--muted); }
.book-text { font: 0.9375rem/1.5 var(--f-ui); color: var(--ink-2); }

/* ---------- Chapter ---------- */
.lesson-head { padding-block: clamp(28px, 5vw, 60px) 28px; }
.lesson-head h1 {
  margin: 12px 0 14px; max-width: 18ch; font: 600 clamp(2.5rem, 6vw, 4.25rem)/1.02 var(--f-display);
  letter-spacing: -0.015em; text-wrap: balance;
}
.lesson-head h1:focus { outline: none; }
.lesson-q { margin: 0; max-width: 40ch; font: italic clamp(1.25rem, 2.4vw, 1.6rem)/1.35 var(--f-display); color: var(--ink-2); text-wrap: balance; }
.jump { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 26px; }
.chip {
  font: 500 0.8125rem/1 var(--f-ui); padding: 8px 13px; border-radius: 999px; cursor: pointer;
  border: 1px solid var(--rule-strong); background: transparent; color: var(--ink-2);
}
.chip:hover { color: var(--ink); border-color: var(--ink-2); }
.sec {
  display: grid; grid-template-columns: 8.5rem minmax(0, 1fr); gap: 8px 36px;
  padding-block: 44px; border-top: 1px solid var(--rule); scroll-margin-top: 70px;
}
.sec-label { padding-top: 0.85rem; font: 600 0.6875rem/1.2 var(--f-ui); letter-spacing: 0.12em; text-transform: uppercase; color: var(--muted); }
.sec-main { display: flex; flex-direction: column; gap: 20px; min-width: 0; }
.sec-main h2 { margin: 0; font: 600 clamp(1.75rem, 3.2vw, 2.25rem)/1.1 var(--f-display); letter-spacing: -0.005em; text-wrap: balance; }
@media (max-width: 900px) {
  .sec { grid-template-columns: minmax(0, 1fr); padding-block: 32px; }
  .sec-label { padding-top: 0; }
}
.prose { max-width: 68ch; font: 1.15rem/1.62 var(--f-display); color: var(--ink); }
.prose p { margin: 0 0 0.9em; }
.prose p:last-child, .prose ul:last-child { margin-bottom: 0; }
.prose ul { margin: 0 0 0.9em; padding-inline-start: 1.3em; }
.prose li { margin-bottom: 0.35em; }
.prose code, .uses code { font: 0.85em var(--f-mono); background: var(--wash); padding: 0.1em 0.35em; border-radius: 4px; }
.terms { display: grid; grid-template-columns: max-content minmax(0, 1fr); gap: 12px 28px; margin: 0; max-width: 68ch; }
.terms dt { font: 600 1.1rem/1.45 var(--f-display); }
.terms dd { margin: 0; font: 1.075rem/1.5 var(--f-display); color: var(--ink-2); }
@media (max-width: 560px) {
  .terms { grid-template-columns: minmax(0, 1fr); gap: 2px; }
  .terms dd { margin-bottom: 12px; }
}
.lab-head { display: flex; flex-direction: column; gap: 8px; }
.bench + .lab-head, .note + .lab-head { margin-top: 28px; }
.lab-head h3 { margin: 0; font: 600 1.6rem/1.15 var(--f-display); text-wrap: balance; }
.lab-intro { font-size: 1.075rem; }

.bench { background: var(--sheet); border: 1px solid var(--rule); border-radius: 14px; min-width: 0; }
.bench-top { display: grid; grid-template-columns: minmax(0, 1fr) 310px; }
.bench-stage { position: relative; min-width: 0; display: flex; flex-direction: column; border-right: 1px solid var(--rule); }
.bench-panel { min-width: 0; padding: 18px; display: flex; flex-direction: column; gap: 18px; }
.panel-group { display: flex; flex-direction: column; gap: 12px; }
.panel-group + .panel-group { border-top: 1px solid var(--rule); padding-top: 16px; }
.panel-title { margin: 0; font: 600 0.6875rem/1.2 var(--f-ui); letter-spacing: 0.12em; text-transform: uppercase; color: var(--muted); }
.bench-foot { display: grid; gap: 30px; padding: 20px 20px 22px; border-top: 1px solid var(--rule); min-width: 0; }
.bench-foot:empty { display: none; }
@media (max-width: 920px) {
  .bench-top { grid-template-columns: minmax(0, 1fr); }
  .bench-stage { border-right: 0; border-bottom: 1px solid var(--rule); }
}
@media (max-width: 480px) { .bench-panel, .bench-foot { padding: 16px; } }
.readout { margin: 0; min-height: 3em; font: 0.875rem/1.5 var(--f-ui); color: var(--ink); white-space: pre-line; }
.stats { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px 14px; margin: 0; }
.stat { min-width: 0; }
.stat dt { font: 0.75rem/1.35 var(--f-ui); color: var(--ink-2); }
.stat dd { margin: 3px 0 0; font: 500 1rem/1.25 var(--f-mono); color: var(--ink); font-variant-numeric: tabular-nums; overflow-wrap: anywhere; }
.keys { display: flex; flex-wrap: wrap; gap: 6px 16px; padding: 4px 16px 14px; font: 0.8125rem/1.4 var(--f-ui); color: var(--ink-2); }
.key { display: inline-flex; align-items: center; gap: 7px; }
.key-mark { flex: none; }
.key-mark.key-dot { width: 10px; height: 10px; border-radius: 50%; background: var(--key); }
.key-mark.key-ring { width: 10px; height: 10px; border-radius: 50%; border: 2px solid var(--key); }
.key-mark.key-line { width: 18px; height: 3px; border-radius: 2px; background: var(--key); }

.net { position: relative; }
.net-canvas { display: block; width: 100%; touch-action: pan-y; }
.net-tip, .chart-tip {
  position: absolute; z-index: 5; pointer-events: none; background: var(--sheet); color: var(--ink);
  border: 1px solid var(--rule-strong); border-radius: 8px; box-shadow: var(--shadow);
  font: 0.8125rem/1.4 var(--f-ui);
}
.net-tip { padding: 6px 9px; white-space: pre-line; max-width: 240px; }
.lattice { display: flex; justify-content: center; padding: 16px 16px 8px; }
.lattice-canvas { display: block; border-radius: 4px; }

.fig { margin: 0; min-width: 0; }
.fig-title { margin: 0 0 8px; font: 600 0.9375rem/1.3 var(--f-ui); }
.fig figcaption { margin-top: 10px; max-width: 74ch; font: 0.8125rem/1.55 var(--f-ui); color: var(--ink-2); }
.fig-num { font-weight: 600; color: var(--ink); }
.fig-pair { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 30px; }
@media (max-width: 760px) { .fig-pair { grid-template-columns: minmax(0, 1fr); } }
.fig-actions { display: flex; flex-wrap: wrap; align-items: center; gap: 12px; margin-bottom: 10px; }
.fig-note { font: 0.8125rem var(--f-ui); color: var(--ink-2); }

.chart { position: relative; min-width: 0; }
.chart-legend { display: flex; flex-wrap: wrap; gap: 6px 16px; margin-bottom: 6px; font: 0.8125rem var(--f-ui); color: var(--ink-2); }
.legend-item { display: inline-flex; align-items: center; gap: 7px; }
.legend-key { flex: none; background: var(--key); }
.legend-key.key-line { width: 16px; height: 2px; border-radius: 1px; }
.legend-key.key-dot { width: 8px; height: 8px; border-radius: 50%; }
.legend-key.key-rect { width: 10px; height: 10px; border-radius: 2px; }
.chart-plot { position: relative; }
.chart-svg { display: block; width: 100%; height: auto; overflow: visible; }
.chart-svg:focus-visible { outline: 2px solid var(--accent); outline-offset: 4px; border-radius: 4px; }
.chart.is-busy .chart-svg { opacity: 0.5; }
.chart-svg .grid line { stroke: var(--rule); stroke-width: 1; }
.chart-svg .baseline, .chart-svg .tick-mark { stroke: var(--rule-strong); stroke-width: 1; }
.chart-svg .ticks text { font: 11px var(--f-mono); fill: var(--muted); }
.chart-svg .axis-label { font: 12px var(--f-ui); fill: var(--ink-2); }
.chart-svg .marker { stroke: var(--ink-2); stroke-width: 1; opacity: 0.6; }
.chart-svg .marker-now { stroke: var(--ink); stroke-width: 1.5; opacity: 0.9; }
.chart-svg .marker-label { font: 11px var(--f-ui); fill: var(--ink-2); }
.chart-svg .marker-label-now { fill: var(--ink); font-weight: 600; }
.chart-svg .dot { stroke: var(--sheet); stroke-width: 2; }
.chart-svg .end-label { font: 12px var(--f-ui); fill: var(--ink-2); }
.chart-svg .crosshair { stroke: var(--ink-2); stroke-width: 1; }
.chart-status {
  position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%); margin: 0;
  padding: 7px 14px; border-radius: 999px; background: var(--sheet); border: 1px solid var(--rule);
  font: 0.8125rem var(--f-ui); color: var(--ink-2); white-space: nowrap; pointer-events: none;
}
.chart-tip { min-width: 150px; padding: 8px 10px; }
.tip-head { margin: 0 0 6px; font-size: 0.75rem; color: var(--ink-2); }
.tip-row { margin: 3px 0 0; display: flex; align-items: center; gap: 8px; }
.tip-row strong { font: 600 0.875rem var(--f-mono); color: var(--ink); }
.tip-key { flex: none; width: 12px; height: 2px; border-radius: 1px; background: var(--key); }
.tip-label { color: var(--ink-2); }
.chart-table { margin-top: 8px; }
.chart-table summary { width: fit-content; cursor: pointer; font: 0.8125rem var(--f-ui); color: var(--ink-2); }
.chart-table .table-wrap { max-height: 300px; overflow: auto; }
.table-wrap { overflow-x: auto; max-width: 100%; }
.sec-main > .table-wrap { max-width: 80ch; }
table.data { border-collapse: collapse; font: 0.875rem/1.4 var(--f-ui); min-width: 100%; }
table.data th { text-align: left; padding: 7px 12px; font-weight: 600; color: var(--ink-2); border-bottom: 1px solid var(--rule-strong); white-space: nowrap; }
table.data td { padding: 7px 12px; border-bottom: 1px solid var(--rule); }
table.data td.num { text-align: right; font-family: var(--f-mono); font-variant-numeric: tabular-nums; }
.chart-table table.data { font-size: 0.8125rem; }

.eq {
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  max-width: 68ch; padding: 14px 18px; border-radius: 10px; background: var(--wash); overflow-x: auto;
}
.eq-body { font: 1.3rem/1.6 var(--f-display); white-space: nowrap; }
.eq-num { flex: none; font: 0.9375rem var(--f-display); color: var(--muted); }
.eq-stack { display: inline-grid; gap: 8px; }
.frac { display: inline-flex; flex-direction: column; align-items: center; vertical-align: middle; margin: 0 0.12em; font-size: 0.9em; line-height: 1.25; }
.frac > span:first-child { padding: 0 0.25em 0.1em; border-bottom: 1px solid currentColor; }
.frac > span:last-child { padding: 0.12em 0.25em 0; }

.note { max-width: 68ch; padding: 16px 18px; border: 1px solid var(--rule); border-radius: 12px; background: var(--sheet); }
.note-title { display: flex; align-items: center; gap: 8px; margin: 0 0 6px; font: 600 0.6875rem/1.2 var(--f-ui); letter-spacing: 0.12em; text-transform: uppercase; color: var(--ink-2); }
.note-title::before { content: ""; flex: none; width: 8px; height: 8px; border-radius: 50%; background: var(--s1); }
.note-myth .note-title::before { background: var(--s2); }
.note-fact .note-title::before { background: var(--s3); }
.note-body { font: 1.05rem/1.55 var(--f-display); }
.note-body p { margin: 0; }

.uses { list-style: none; margin: 0; padding: 0; display: grid; gap: 22px 32px; grid-template-columns: repeat(3, minmax(0, 1fr)); }
.uses-2, .uses-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.uses li { min-width: 0; padding-top: 12px; border-top: 1px solid var(--rule-strong); }
.uses h3 { margin: 0 0 6px; font: 600 1rem/1.3 var(--f-ui); }
.uses p { margin: 0; font: 0.9375rem/1.55 var(--f-ui); color: var(--ink-2); }
@media (max-width: 760px) { .uses, .uses-2, .uses-4 { grid-template-columns: minmax(0, 1fr); } }

.code { max-width: 84ch; border: 1px solid var(--rule); border-radius: 12px; background: var(--sheet); overflow: hidden; }
.code-head { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 6px 8px 6px 14px; border-bottom: 1px solid var(--rule); font: 0.75rem var(--f-ui); color: var(--ink-2); }
.code pre { margin: 0; padding: 14px 16px; overflow-x: auto; font: 0.8125rem/1.65 var(--f-mono); color: var(--ink); tab-size: 4; }
.tk-k { color: var(--code-k); font-weight: 600; }
.tk-s { color: var(--code-s); }
.tk-c { color: var(--muted); font-style: italic; }

.refs { margin: 0; padding-inline-start: 1.4em; max-width: 80ch; display: grid; gap: 10px; font: 0.9375rem/1.55 var(--f-ui); color: var(--ink-2); }
.refs cite { font-style: italic; color: var(--ink); }
.refs a { overflow-wrap: anywhere; }

.pager { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; padding-block: 36px 60px; border-top: 1px solid var(--rule); }
.pager a { display: flex; flex-direction: column; gap: 4px; padding: 16px 18px; border: 1px solid var(--rule); border-radius: 12px; background: var(--sheet); color: inherit; text-decoration: none; min-width: 0; }
.pager a:hover { border-color: var(--ink-2); }
.pager .next { grid-column: 2; text-align: end; }
.pager-dir { font: 600 0.6875rem/1.2 var(--f-ui); letter-spacing: 0.12em; text-transform: uppercase; color: var(--muted); }
.pager-title { font: 600 1.15rem/1.3 var(--f-display); }
@media (max-width: 560px) { .pager { grid-template-columns: minmax(0, 1fr); } .pager .next { grid-column: 1; } }
.error { padding: 16px; border: 1px solid var(--rule-strong); border-radius: 10px; }

.site-foot { border-top: 1px solid var(--rule); }
.foot-row { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 12px 32px; padding-block: 28px 44px; font: 0.8125rem/1.6 var(--f-ui); color: var(--ink-2); }
.foot-row p { margin: 0; max-width: 62ch; }
noscript p { padding: 24px 0; font: 1rem var(--f-ui); }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; animation: none !important; }
}

h1[tabindex="-1"]:focus { outline: none; }

/* Faint 3D network globe behind the page (Persian edition). */
.backdrop { position: fixed; inset: 0; width: 100%; height: 100%; z-index: 0; pointer-events: none; }