/* Backprop versus the memory wall — stylesheet
 * Tokens first (light in :root, dark under media query + data-theme), then layout, then components.
 * Series colors follow one rule everywhere: orange = arithmetic (FLOPs), blue = bytes (memory).
 */
:root {
  color-scheme: light;
  --bg: #f6f6f2;
  --surface: #fcfcfa;
  --surface-2: #efeee8;
  --ink: #17191b;
  --ink-2: #464b50;
  --muted: #7b8086;
  --grid: #e3e4de;
  --axis: #c3c5bf;
  --border: rgba(23, 25, 27, 0.12);
  --accent: #1f5f8b;
  --accent-ink: #ffffff;
  --link: #1f5f8b;
  --series-compute: #eb6834;
  --series-memory: #2a78d6;
  --series-3: #1baf7a;
  --series-4: #eda100;
  --series-5: #e87ba4;
  --series-6: #4a3aa7;
  --board-bg: #1e2a31;
  --board-ink: #e8ece8;
  --board-muted: #a9b3b8;
  --board-chalk: #f2cd6e;
  --board-line: rgba(255, 255, 255, 0.14);
  --good: #0ca30c;
  --warn: #fab219;
  --crit: #d03b3b;
  --font-display: "Newsreader", Georgia, "Times New Roman", serif;
  --font-body: "Newsreader", Georgia, "Times New Roman", serif;
  --font-ui: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --measure: 44rem;
  --wide: 68rem;
  --radius: 6px;
  --shadow: 0 1px 2px rgba(23, 25, 27, 0.06), 0 8px 24px -12px rgba(23, 25, 27, 0.18);
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --bg: #131515;
    --surface: #1b1e1e;
    --surface-2: #232727;
    --ink: #f1f2ee;
    --ink-2: #c3c6c0;
    --muted: #8d9297;
    --grid: #2b2f2f;
    --axis: #3d4243;
    --border: rgba(241, 242, 238, 0.12);
    --accent: #6fb0e0;
    --accent-ink: #0d1117;
    --link: #7fbbe8;
    --series-compute: #d95926;
    --series-memory: #3987e5;
    --series-3: #199e70;
    --series-4: #c98500;
    --series-5: #d55181;
    --series-6: #9085e9;
    --board-bg: #243139;
    --board-ink: #eef1ee;
    --board-muted: #a9b3b8;
    --board-chalk: #f2cd6e;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 8px 24px -12px rgba(0, 0, 0, 0.6);
  }
}
:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #131515;
  --surface: #1b1e1e;
  --surface-2: #232727;
  --ink: #f1f2ee;
  --ink-2: #c3c6c0;
  --muted: #8d9297;
  --grid: #2b2f2f;
  --axis: #3d4243;
  --border: rgba(241, 242, 238, 0.12);
  --accent: #6fb0e0;
  --accent-ink: #0d1117;
  --link: #7fbbe8;
  --series-compute: #d95926;
  --series-memory: #3987e5;
  --series-3: #199e70;
  --series-4: #c98500;
  --series-5: #d55181;
  --series-6: #9085e9;
  --board-bg: #243139;
  --board-ink: #eef1ee;
  --board-muted: #a9b3b8;
  --board-chalk: #f2cd6e;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 8px 24px -12px rgba(0, 0, 0, 0.6);
}

/* ---------- base ---------- */
* { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; } }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 18px;
  line-height: 1.55;
  padding-inline: 20px;
  padding-block: 0 96px;
}
a { color: var(--link); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
img, svg { max-width: 100%; height: auto; }
h1, h2, h3, h4 { font-family: var(--font-display); font-weight: 500; line-height: 1.15; text-wrap: balance; margin: 0; }
h1 { font-size: clamp(2.2rem, 5vw, 3.6rem); letter-spacing: -0.01em; font-weight: 400; }
h2 { font-size: clamp(1.7rem, 3vw, 2.2rem); margin-top: 3.5rem; margin-bottom: 1rem; }
h3 { font-size: 1.3rem; margin-top: 2.2rem; margin-bottom: 0.6rem; }
h4 { font-size: 1.05rem; font-family: var(--font-ui); font-weight: 600; margin-top: 1.6rem; margin-bottom: 0.4rem; }
p { margin: 0 0 1.1em; }
strong { font-weight: 600; }
code, kbd, samp { font-family: var(--font-mono); font-size: 0.86em; }
code { background: var(--surface-2); padding: 0.05em 0.35em; border-radius: 4px; }
pre { background: var(--surface-2); padding: 14px 16px; border-radius: var(--radius); overflow-x: auto; font-size: 0.85rem; line-height: 1.45; }
pre code { background: none; padding: 0; }
hr { border: 0; border-top: 1px solid var(--border); margin: 3rem 0; }
blockquote { margin: 1.4rem 0; padding: 0.2rem 0 0.2rem 1.2rem; border-left: 3px solid var(--axis); color: var(--ink-2); font-style: italic; }
blockquote cite { display: block; font-style: normal; font-family: var(--font-ui); font-size: 0.85rem; color: var(--muted); margin-top: 0.4rem; }
ul, ol { padding-left: 1.4rem; }
li { margin-bottom: 0.35em; }
.eyebrow { font-family: var(--font-ui); font-size: 0.78rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); font-weight: 500; }
.num, .mono { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }
.small { font-size: 0.9rem; color: var(--ink-2); }
.muted { color: var(--muted); }
.katex { font-size: 1.02em; }
.katex-display { overflow-x: auto; overflow-y: hidden; padding: 0.2em 0; }

/* ---------- layout ---------- */
.page { max-width: var(--wide); margin: 0 auto; }
.masthead { padding-block: 40px 28px; border-bottom: 1px solid var(--border); margin-bottom: 40px; }
.masthead .eyebrow { margin-bottom: 14px; }
.masthead .dek { font-size: 1.25rem; color: var(--ink-2); max-width: 40rem; margin-top: 18px; line-height: 1.45; }
.masthead .byline { font-family: var(--font-ui); font-size: 0.9rem; color: var(--muted); margin-top: 22px; display: flex; flex-wrap: wrap; gap: 8px 22px; align-items: center; }
.masthead .byline a { color: var(--ink-2); }
.layout { display: grid; grid-template-columns: 1fr; gap: 0 48px; }
@media (min-width: 1180px) {
  .layout { grid-template-columns: 220px minmax(0, 1fr); }
  .toc { position: sticky; top: 24px; align-self: start; max-height: calc(100vh - 48px); overflow-y: auto; }
}
.toc { font-family: var(--font-ui); font-size: 0.86rem; margin-bottom: 32px; }
.toc summary { cursor: pointer; font-weight: 600; color: var(--ink-2); list-style: none; }
.toc summary::-webkit-details-marker { display: none; }
.toc summary::before { content: "☰ "; }
@media (min-width: 1180px) { .toc summary { pointer-events: none; } .toc summary::before { content: ""; } .toc details[open] summary { margin-bottom: 8px; } }
.toc ol { list-style: none; padding: 0; margin: 10px 0 0; }
.toc li { margin: 0; }
.toc a { display: block; padding: 5px 10px; color: var(--ink-2); text-decoration: none; border-left: 2px solid transparent; line-height: 1.3; }
.toc a:hover { color: var(--ink); background: var(--surface-2); }
.toc a.active { border-left-color: var(--accent); color: var(--ink); font-weight: 600; }
.toc .sub a { padding-left: 22px; font-size: 0.8rem; }
main { min-width: 0; }
.prose { max-width: var(--measure); }
.prose > * { max-width: var(--measure); }
.prose > .figure, .prose > .wide, .prose > .board.wide, .prose > .table-wrap { max-width: none; }

/* ---------- the board (a blackboard-lecture callout) ---------- */
.board {
  background: var(--board-bg); color: var(--board-ink);
  border-radius: var(--radius); padding: 22px 26px 20px; margin: 1.8rem 0 2rem;
  box-shadow: var(--shadow);
  font-family: var(--font-mono); font-size: 0.92rem; line-height: 1.5;
  position: relative;
}
.board::before { content: ""; position: absolute; inset: 8px; border: 1px solid var(--board-line); border-radius: 3px; pointer-events: none; }
.board .eyebrow { color: var(--board-chalk); margin-bottom: 10px; }
.board .katex { color: var(--board-ink); }
.board .katex-display { margin: 0.6em 0; }
.board p { margin: 0 0 0.7em; font-family: var(--font-body); font-size: 1rem; }
.board p:last-child { margin-bottom: 0; }
.board .line { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 16px; padding: 6px 0; border-top: 1px solid var(--board-line); }
.board .line:first-of-type { border-top: 0; }
.board .line .v { color: var(--board-chalk); text-align: right; white-space: nowrap; }
.board .note { color: var(--board-muted); font-family: var(--font-ui); font-size: 0.82rem; margin-top: 10px; }
.board a { color: var(--board-chalk); }

/* ---------- figures ---------- */
.figure { margin: 2rem 0 2.4rem; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px 20px 16px; }
.figure .fig-head { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 6px 16px; align-items: baseline; margin-bottom: 10px; }
.figure .fig-title { font-family: var(--font-ui); font-weight: 600; font-size: 1rem; }
.figure .fig-title .eyebrow { display: inline; margin-right: 8px; }
.figure .fig-sub { font-family: var(--font-ui); font-size: 0.85rem; color: var(--ink-2); }
.figure .controls { display: flex; flex-wrap: wrap; gap: 10px 18px; align-items: end; margin: 8px 0 12px; font-family: var(--font-ui); font-size: 0.84rem; }
.figure .control { display: flex; flex-direction: column; gap: 4px; min-width: 120px; }
.figure .control label { color: var(--ink-2); font-size: 0.78rem; letter-spacing: 0.02em; }
.figure .control .val { font-family: var(--font-mono); font-size: 0.84rem; color: var(--ink); }
.figure select, .figure input[type="number"] { font-family: var(--font-ui); font-size: 0.86rem; padding: 5px 8px; border: 1px solid var(--axis); border-radius: 4px; background: var(--surface); color: var(--ink); max-width: 100%; }
.figure input[type="range"] { width: 180px; max-width: 100%; accent-color: var(--accent); }
.figure .toggle { display: inline-flex; align-items: center; gap: 6px; padding: 4px 0; }
.figure .toggle input { accent-color: var(--accent); }
.figure .seg { display: inline-flex; border: 1px solid var(--axis); border-radius: 4px; overflow: hidden; }
.figure .seg button { font-family: var(--font-ui); font-size: 0.8rem; padding: 5px 10px; border: 0; background: var(--surface); color: var(--ink-2); cursor: pointer; }
.figure .seg button + button { border-left: 1px solid var(--axis); }
.figure .seg button[aria-pressed="true"] { background: var(--accent); color: var(--accent-ink); }
.figure .btn { font-family: var(--font-ui); font-size: 0.8rem; padding: 5px 10px; border: 1px solid var(--axis); border-radius: 4px; background: var(--surface); color: var(--ink-2); cursor: pointer; }
.figure .btn:hover { border-color: var(--accent); color: var(--ink); }
.figure .btn[aria-pressed="true"] { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.figure .plot { width: 100%; }
.figure .plots { display: grid; grid-template-columns: 1fr; gap: 12px; }
@media (min-width: 900px) { .figure .plots.two { grid-template-columns: 1fr 1fr; } .figure .plots.three { grid-template-columns: 1fr 1fr 1fr; } }
.figure .caption { font-family: var(--font-ui); font-size: 0.84rem; color: var(--ink-2); margin-top: 10px; line-height: 1.45; }
.figure .readout { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 10px 16px; margin: 10px 0 4px; font-family: var(--font-ui); }
.figure .stat { border-top: 2px solid var(--grid); padding-top: 6px; }
.figure .stat .l { font-size: 0.74rem; color: var(--muted); letter-spacing: 0.03em; text-transform: uppercase; }
.figure .stat .v { font-size: 1.35rem; font-weight: 600; line-height: 1.2; }
.figure .stat .v small { font-size: 0.8rem; font-weight: 500; color: var(--ink-2); margin-left: 3px; }
.figure .stat.hot { border-top-color: var(--series-compute); }
.figure .stat.cold { border-top-color: var(--series-memory); }
.figure details.tableview { margin-top: 10px; font-family: var(--font-ui); font-size: 0.82rem; }
.figure details.tableview summary { cursor: pointer; color: var(--ink-2); }
.viz-legend { display: flex; flex-wrap: wrap; gap: 6px 18px; font-family: var(--font-ui); font-size: 0.8rem; color: var(--ink-2); margin: 6px 0 4px; }
.viz-legend-item { display: inline-flex; align-items: center; gap: 7px; }
.viz-legend-key { display: inline-block; width: 18px; height: 2px; border-radius: 1px; }
.viz-legend-key.rect { width: 12px; height: 12px; border-radius: 2px; }
.viz-legend-key.dot { width: 9px; height: 9px; border-radius: 50%; }
.viz-legend-key.dashed { background: none !important; border-top: 2px dashed currentColor; height: 0; }
.viz-tip { position: fixed; z-index: 50; display: none; pointer-events: none; background: var(--ink); color: var(--bg); padding: 8px 11px; border-radius: 6px; font-family: var(--font-ui); font-size: 0.8rem; line-height: 1.4; box-shadow: var(--shadow); max-width: 320px; }
.viz-tip-title { font-weight: 600; margin-bottom: 4px; }
.viz-tip-row { display: flex; align-items: center; gap: 7px; }
.viz-tip-row strong { font-variant-numeric: tabular-nums; }
.viz-tip-row span:last-child { opacity: 0.8; }
.viz-tip-key { display: inline-block; width: 12px; height: 2px; }
.axis text { font-family: var(--font-ui); }

/* ---------- tables ---------- */
.table-wrap { overflow-x: auto; margin: 1.4rem 0 2rem; }
.data-table { border-collapse: collapse; width: 100%; font-family: var(--font-ui); font-size: 0.84rem; line-height: 1.35; }
.data-table caption { text-align: left; font-weight: 600; padding-bottom: 8px; color: var(--ink-2); caption-side: top; }
.data-table th { text-align: left; font-weight: 600; color: var(--ink-2); border-bottom: 1px solid var(--axis); padding: 8px 10px 8px 0; vertical-align: bottom; }
.data-table td { padding: 7px 10px 7px 0; border-bottom: 1px solid var(--grid); vertical-align: top; }
.data-table td.num, .data-table th.num { text-align: right; font-family: var(--font-mono); font-variant-numeric: tabular-nums; white-space: nowrap; }
.data-table tr.hl td { background: var(--surface-2); }
.data-table .tag { font-size: 0.7rem; padding: 1px 6px; border-radius: 10px; background: var(--surface-2); color: var(--ink-2); white-space: nowrap; }
.data-table tbody tr:hover td { background: var(--surface-2); }

/* ---------- misc components ---------- */
.aside { font-family: var(--font-ui); font-size: 0.9rem; color: var(--ink-2); border-left: 3px solid var(--grid); padding-left: 14px; margin: 1.4rem 0; }
.ledger { display: grid; grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); gap: 14px; margin: 1.4rem 0 2rem; }
.ledger .card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 14px 16px; }
.ledger .card .l { font-family: var(--font-ui); font-size: 0.74rem; text-transform: uppercase; letter-spacing: 0.05em; color: var(--muted); }
.ledger .card .v { font-family: var(--font-ui); font-size: 1.6rem; font-weight: 600; margin: 4px 0 2px; }
.ledger .card .s { font-family: var(--font-ui); font-size: 0.82rem; color: var(--ink-2); }
.trade { display: grid; grid-template-columns: 1fr; gap: 0; border-top: 1px solid var(--axis); margin: 1.2rem 0 2rem; font-family: var(--font-ui); font-size: 0.9rem; }
.trade .row { display: grid; grid-template-columns: 170px 1fr; gap: 12px; padding: 12px 0; border-bottom: 1px solid var(--grid); }
.trade .row .k { font-weight: 600; color: var(--ink); }
.trade .row .k small { display: block; font-weight: 400; color: var(--muted); font-size: 0.75rem; }
.trade .row .gives { color: var(--series-compute); font-weight: 600; }
.trade .row .gets { color: var(--series-memory); font-weight: 600; }
@media (max-width: 560px) { .trade .row { grid-template-columns: 1fr; gap: 4px; } }
.pill { display: inline-block; font-family: var(--font-ui); font-size: 0.72rem; padding: 2px 8px; border-radius: 12px; background: var(--surface-2); color: var(--ink-2); vertical-align: middle; }
.pill.est { background: color-mix(in srgb, var(--series-4) 18%, transparent); }
.pill.ver { background: color-mix(in srgb, var(--series-3) 18%, transparent); }
.footnotes { font-family: var(--font-ui); font-size: 0.86rem; color: var(--ink-2); }
.footnotes li { margin-bottom: 0.6em; }
.theme-toggle { font-family: var(--font-ui); font-size: 0.8rem; border: 1px solid var(--axis); border-radius: 4px; background: var(--surface); color: var(--ink-2); padding: 4px 10px; cursor: pointer; }
.sources-list { font-family: var(--font-ui); font-size: 0.86rem; }
.sources-list li { margin-bottom: 0.5em; }
.counter { counter-reset: h2; }
.counter h2::before { counter-increment: h2; content: counter(h2) ". "; color: var(--muted); font-weight: 400; }
.hero-figure { font-family: var(--font-ui); font-size: clamp(2.6rem, 6vw, 4rem); font-weight: 600; line-height: 1; letter-spacing: -0.02em; margin: 0.4em 0 0.2em; }
.hero-figure small { font-size: 1rem; font-weight: 500; color: var(--ink-2); display: block; letter-spacing: 0; margin-top: 8px; }
.two-col { display: grid; grid-template-columns: 1fr; gap: 20px 32px; margin: 1.2rem 0 1.6rem; }
@media (min-width: 760px) { .two-col { grid-template-columns: 1fr 1fr; } }
.two-col .col { min-width: 0; }
.two-col .col h4 { margin-top: 0; }
.timeline-note { font-family: var(--font-ui); font-size: 0.8rem; color: var(--muted); }
footer.colophon { margin-top: 64px; padding-top: 24px; border-top: 1px solid var(--border); font-family: var(--font-ui); font-size: 0.84rem; color: var(--muted); }
.print-only { display: none; }
@media print { .toc, .theme-toggle, .figure .controls { display: none; } .figure { break-inside: avoid; } }