:root {
  --paper: #f1ece2;
  --sheet: #fbf8f1;
  --ink: #1b1a17;
  --ink-2: #514c43;
  --ink-3: #8a8377;
  --rule: #d9d0c0;
  --subq: #b5441c;
  --jev: #1d6a56;
  --mono: "IBM Plex Mono", ui-monospace, Menlo, monospace;
  --sans: "IBM Plex Sans", system-ui, sans-serif;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #151412;
    --sheet: #1e1d1a;
    --ink: #ece6d9;
    --ink-2: #b9b1a2;
    --ink-3: #7d766a;
    --rule: #39352f;
    --subq: #e2763f;
    --jev: #52b293;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 400 16px/1.6 var(--sans);
}
a { color: inherit; text-underline-offset: 3px; }
.mono, pre, code { font-family: var(--mono); }
.muted { color: var(--ink-2); }
.small { font-size: 13px; }
.c-subq { color: var(--subq); }
.c-jev { color: var(--jev); }

.bar {
  display: flex; justify-content: space-between; align-items: center;
  max-width: 1080px; margin: 0 auto; padding: 16px 20px;
  font: 500 14px var(--mono);
}
.bar nav { display: flex; gap: 16px; align-items: center; }
.bar a { text-decoration: none; color: var(--ink-2); }
.bar a:hover { color: var(--ink); text-decoration: underline; }
button {
  font: 500 13px var(--mono); color: var(--ink); background: transparent;
  border: 1px solid var(--rule); border-radius: 6px; padding: 5px 10px; cursor: pointer;
  transition: background-color .15s, border-color .15s;
}
button:hover { border-color: var(--ink-3); }
button[aria-pressed="true"] { background: var(--ink); color: var(--paper); border-color: var(--ink); }

main { max-width: 1080px; margin: 0 auto; padding: 0 20px; }

/* hero */
.hero {
  display: grid; grid-template-columns: 1.1fr 1fr; gap: 28px 40px;
  padding: 40px 0 64px; align-items: start;
}
.hero-text { grid-column: 1 / -1; max-width: 760px; }
h1 {
  font: 600 clamp(40px, 7vw, 76px)/1 var(--mono); letter-spacing: -0.03em; margin: 0 0 20px;
}
.lede { font-size: clamp(18px, 2.2vw, 21px); line-height: 1.5; color: var(--ink-2); margin: 0; max-width: 640px; }

.paper {
  background: var(--sheet);
  box-shadow: 0 1px 2px rgba(0,0,0,.06);
  padding: 20px 22px 26px;
  position: relative;
  /* torn receipt edge at the bottom */
  --tooth: 7px;
  mask: conic-gradient(from -45deg at bottom, #0000, #000 1deg 89deg, #0000 90deg) 50% / calc(2 * var(--tooth)) 100%;
  padding-bottom: calc(26px + var(--tooth));
}
.ticket-head, .receipt-head {
  font: 500 13px var(--mono); color: var(--ink-2);
  border-bottom: 1px dashed var(--rule); padding-bottom: 10px; margin-bottom: 12px;
  display: flex; justify-content: space-between; gap: 12px;
}
.log {
  margin: 0; min-height: 7.6em; font-size: 12.5px; line-height: 1.55;
  white-space: pre-wrap; overflow-wrap: anywhere; color: var(--ink);
}
.log .hl { background: color-mix(in srgb, var(--subq) 16%, transparent); }
.log .caret { display: inline-block; width: .6em; background: var(--ink); animation: blink 1s steps(1) infinite; }
@keyframes blink { 50% { opacity: 0; } }
.ticket-q { border-top: 1px dashed var(--rule); margin-top: 14px; padding-top: 12px; }
.label { font: 500 12px var(--mono); color: var(--ink-3); }
.q { margin: 2px 0 10px; font-size: 16px; font-weight: 500; min-height: 1.5em; }
.meters { display: grid; gap: 10px; }
.meter { display: grid; grid-template-columns: 48px 1fr 54px; align-items: center; gap: 10px; font: 500 13px var(--mono); }
.track { position: relative; height: 18px; border-bottom: 1px solid var(--ink-3); }
.track .tick { position: absolute; bottom: -1px; width: 1px; height: 6px; background: var(--ink-3); }
.track .half { height: 18px; background: var(--rule); }
.track .needle {
  position: absolute; bottom: -1px; left: 0; width: 2px; height: 22px;
  transition: left 1.4s cubic-bezier(.2,.8,.2,1);
}
.meter .val { text-align: right; font-variant-numeric: tabular-nums; }
.ticket-foot { display: grid; gap: 2px; margin-top: 14px; font-size: 13px; }

.receipt ol { list-style: none; margin: 0; padding: 0; }
.receipt li {
  display: grid; grid-template-columns: 1fr auto auto; gap: 14px; align-items: baseline;
  padding: 7px 0; font-size: 14px;
  opacity: 0; transition: opacity .4s;
}
.receipt li.in { opacity: 1; }
.receipt li .name { display: flex; align-items: baseline; gap: 8px; min-width: 0; }
.receipt li .name::after { content: ""; flex: 1; border-bottom: 1px dotted var(--ink-3); transform: translateY(-4px); }
.receipt li .v { font: 500 15px var(--mono); font-variant-numeric: tabular-nums; min-width: 64px; text-align: right; }
.receipt li .v small { font-size: 11px; color: var(--ink-3); font-weight: 400; display: block; line-height: 1; }
.receipt .cols { display: grid; grid-template-columns: 64px 64px; gap: 14px; text-align: right; }
.receipt-foot { font-size: 13px; color: var(--ink-2); border-top: 1px dashed var(--rule); margin: 12px 0 0; padding-top: 10px; }

/* sections */
.block { padding: 56px 0; border-top: 1px solid var(--rule); }
h2 { font: 600 clamp(26px, 3.6vw, 36px)/1.15 var(--mono); letter-spacing: -0.02em; margin: 0 0 14px; }
h3 { font: 600 18px var(--mono); margin: 32px 0 10px; }
.prose { max-width: 680px; color: var(--ink-2); margin: 0 0 28px; }
.finding {
  max-width: 720px; font-size: 18px; line-height: 1.5; margin: 28px 0 0;
  padding-left: 16px; border-left: 3px solid var(--ink);
}

/* tape */
.tape { margin: 8px 0 28px; }
.tape-caption { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px; font: 500 12px var(--mono); color: var(--ink-3); margin-bottom: 8px; }
.tape-key { display: inline-flex; align-items: center; gap: 6px; }
.tape-key i { display: inline-block; width: 14px; height: 10px; }
.k-window { border: 1.5px solid var(--jev); }
.k-cut { border-left: 1.5px dashed var(--jev); width: 6px !important; margin-left: 8px; }
.tape-row { display: grid; grid-template-columns: 48px 1fr; align-items: center; gap: 10px; height: 22px; }
.tape-row .len { font: 500 12px var(--mono); color: var(--ink-2); text-align: right; }
.tape-row .strip-wrap { position: relative; height: 12px; }
.tape-row .strip {
  position: absolute; inset: 0 auto 0 0; width: 0; min-width: 2px;
  background: repeating-linear-gradient(90deg, var(--ink) 0 1px, transparent 1px 3px);
  opacity: .55; transition: width 1.2s cubic-bezier(.3,.7,.2,1);
}
.tape-row .window { position: absolute; top: -3px; bottom: -3px; left: 0; border: 1.5px solid var(--jev); opacity: 0; transition: opacity .4s 1.1s; }
.tape-row .cut { position: absolute; top: -4px; bottom: -4px; border-left: 1.5px dashed var(--jev); opacity: 0; transition: opacity .3s; }
.tape.in .window, .tape.in .cut { opacity: 1; }

/* charts */
.chart { margin: 0; }
.chart svg, .calib svg { width: 100%; height: auto; display: block; overflow: visible; }
.axis text, .lbl { font: 400 11px var(--mono); fill: var(--ink-3); }
.axis line, .axis path { stroke: var(--rule); }
.gridline { stroke: var(--rule); stroke-dasharray: 2 3; }
.series { fill: none; stroke-width: 2.5; stroke-linecap: round; stroke-linejoin: round; }
.series.draw { transition: stroke-dashoffset 1.8s cubic-bezier(.3,.6,.2,1); }
.dot { opacity: 0; transition: opacity .3s; }
.in .dot { opacity: 1; }
.ci { stroke-width: 1.5; opacity: .45; }
.band { fill: color-mix(in srgb, var(--jev) 9%, transparent); }
.col-hit { fill: transparent; cursor: pointer; }
.col-sel { fill: color-mix(in srgb, var(--ink) 6%, transparent); }
.legend { display: flex; flex-wrap: wrap; gap: 6px 18px; margin-top: 10px; font: 500 12px var(--mono); color: var(--ink-2); }
.legend span { display: inline-flex; align-items: center; gap: 6px; }
.legend svg { width: 22px; height: 10px; }

.readout { margin-top: 28px; }
.sizes { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 8px; }
.readout-grid { display: grid; grid-template-columns: minmax(150px, 1fr) 1fr 1fr; gap: 0 14px; margin-top: 12px; font-size: 14px; }
.readout-grid .h { font: 500 12px var(--mono); color: var(--ink-3); padding-bottom: 6px; border-bottom: 1px solid var(--rule); }
.readout-grid > div:not(.h) { padding: 6px 0; border-bottom: 1px solid var(--rule); }
.bar-cell { display: flex; align-items: center; gap: 8px; font: 500 13px var(--mono); font-variant-numeric: tabular-nums; }
.bar-cell .b { height: 8px; transition: width .5s cubic-bezier(.3,.7,.2,1); }
.bar-cell .na { color: var(--ink-3); font-weight: 400; }

.sub-h { font-size: 22px; margin-top: 48px; }
.auto-grid { grid-template-columns: minmax(120px, 1fr) 1.2fr 1.2fr; max-width: 820px; margin-bottom: 4px; }
.auto-grid .bar-cell { white-space: nowrap; }
.auto-grid .bar-cell .na { font-size: 11.5px; }

/* heat grids */
.grids { display: grid; grid-template-columns: 1fr 1fr; gap: 32px; }
.grid-title { font: 600 15px var(--mono); margin: 0 0 8px; display: flex; gap: 8px; align-items: baseline; }
.heat { display: grid; grid-template-columns: minmax(120px, 1.6fr) repeat(8, 1fr); gap: 2px; font-size: 12px; }
.heat .rowh { font-size: 12px; line-height: 1.25; color: var(--ink-2); padding-right: 6px; display: flex; align-items: center; }
.heat .colh { font: 500 10.5px var(--mono); color: var(--ink-3); text-align: center; padding-bottom: 4px; }
.heat .cell {
  font: 500 11px var(--mono); text-align: center; padding: 8px 0; font-variant-numeric: tabular-nums;
  opacity: 0; transition: opacity .35s;
}
.heat .cell.chunked { background-image: repeating-linear-gradient(135deg, transparent 0 4px, rgba(127,127,127,.18) 4px 5px); }
.heat .cell.empty { color: var(--ink-3); }
.in .heat .cell { opacity: 1; }
.depth { font-size: 15px; color: var(--ink-2); margin-top: 18px; max-width: 760px; }
.depth b { font: 600 14px var(--mono); }

/* calibration */
.calib { display: grid; grid-template-columns: 1fr 1fr; gap: 32px; }
.calib h4 { font: 600 15px var(--mono); margin: 0 0 4px; display: flex; justify-content: space-between; }
.calib h4 span { font-weight: 400; color: var(--ink-2); font-size: 13px; }
.calib .pt { transition: transform 1s cubic-bezier(.3,.7,.2,1), opacity .6s; }

/* robustness */
.robust { display: grid; gap: 0; }
.rb { display: grid; grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr) minmax(0, 1fr); gap: 20px; align-items: center; padding: 18px 0; border-bottom: 1px solid var(--rule); }
.rb:first-child { border-top: 1px solid var(--rule); }
.rb .what { font-weight: 500; }
.rb .demo { font: 12px var(--mono); color: var(--ink-2); margin-top: 8px; min-height: 30px; }
.rb .opts { display: flex; gap: 4px; position: relative; }
.rb .opt { border: 1px solid var(--rule); border-radius: 4px; padding: 1px 6px; transition: transform .5s cubic-bezier(.3,.7,.2,1); background: var(--sheet); }
.rb .res { font-family: var(--mono); }
.rb .res .big { font-size: 26px; font-weight: 600; font-variant-numeric: tabular-nums; line-height: 1.1; }
.rb .res .sub { font-size: 12px; color: var(--ink-2); }
.rb .res .who { font-size: 12px; font-weight: 600; }
.typing::after { content: "▍"; animation: blink 1s steps(1) infinite; }

/* race */
.race { display: grid; gap: 14px; margin-top: 12px; }
.lane { display: grid; grid-template-columns: 70px 1fr 74px; align-items: center; gap: 12px; font: 500 13px var(--mono); }
.lane .track2 { position: relative; height: 26px; border-bottom: 1px solid var(--ink-3); }
.lane .runner { position: absolute; left: 0; bottom: 4px; width: 14px; height: 14px; border-radius: 50%; }
.lane .trail { position: absolute; left: 0; bottom: 10px; height: 2px; width: 0; opacity: .5; }
.lane .seg { position: absolute; bottom: -1px; width: 1px; height: 8px; background: var(--ink-3); }
.lane .time { text-align: right; font-variant-numeric: tabular-nums; }
.lane .meta { grid-column: 2; font-size: 11.5px; color: var(--ink-3); margin-top: -8px; }
.cost { margin: 26px 0 12px; font-size: 14px; }
.cost .row { display: grid; grid-template-columns: 1fr 90px 90px; gap: 14px; padding: 6px 0; border-bottom: 1px solid var(--rule); font-family: var(--mono); font-variant-numeric: tabular-nums; }
.cost .row span:not(:first-child) { text-align: right; }
.cost .row.h { color: var(--ink-3); font-size: 12px; }

/* takeaways */
.takeaways { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; }
.takeaways h3 { margin: 0 0 10px; font-size: 20px; }
.tk-h { font: 600 13px var(--mono); color: var(--ink-2); margin: 18px 0 6px; }
.tk { list-style: none; margin: 0; padding: 0; }
.tk li { display: grid; grid-template-columns: 18px 1fr; padding: 7px 0; border-bottom: 1px solid var(--rule); font-size: 15px; }
.tk li:first-child { border-top: 1px solid var(--rule); }
.tk-mark { font: 600 15px var(--mono); color: var(--ink-3); }
@media (max-width: 820px) { .takeaways { grid-template-columns: 1fr; gap: 24px; } }

/* method */
.method { max-width: 760px; padding-left: 22px; color: var(--ink-2); }
.method li { margin-bottom: 10px; }
.code { background: var(--sheet); border: 1px solid var(--rule); border-radius: 6px; padding: 14px 16px; font-size: 13px; overflow-x: auto; max-width: 760px; }
.foot { max-width: 1080px; margin: 0 auto; padding: 28px 20px 48px; border-top: 1px solid var(--rule); color: var(--ink-2); font-size: 14px; }

@media (max-width: 820px) {
  .hero { grid-template-columns: 1fr; padding-top: 20px; }
  .grids, .calib { grid-template-columns: 1fr; }
  .rb { grid-template-columns: 1fr 1fr; }
  .rb .left { grid-column: 1 / -1; }
  .heat { grid-template-columns: minmax(96px, 1.4fr) repeat(8, 1fr); }
  .heat .cell { font-size: 9.5px; padding: 7px 0; }
  .readout-grid { grid-template-columns: minmax(110px, 1.2fr) 1fr 1fr; font-size: 13px; }
}
@media (max-width: 480px) {
  .auto-grid .bar-cell { white-space: normal; flex-wrap: wrap; gap: 2px 6px; }
  .auto-grid .bar-cell .na { flex-basis: 100%; }
  main, .bar, .foot { padding-left: 16px; padding-right: 16px; }
  .paper { padding-left: 16px; padding-right: 16px; }
  .receipt li { grid-template-columns: 1fr 56px 56px; gap: 8px; font-size: 13px; }
  .receipt .cols { grid-template-columns: 56px 56px; gap: 8px; }
  .receipt li .v { min-width: 0; font-size: 14px; }
  .heat .colh { font-size: 9px; }
  .lane { grid-template-columns: 52px 1fr 62px; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; animation: none !important; }
}