/* The demo page's styles: a ledger book, ruled paper with debit and credit columns. */
:root {
  --paper: #eef1e6;
  --paper-deep: #e2e8d8;
  --ink: #1d2a30;
  --ink-soft: #4b5a55;
  --rule: #c4d3c2;
  --rule-strong: #8fab95;
  --accent: #2c6849;
  --signal: #b3312b;
  --signal-wash: rgb(179 49 43 / .09);
  --accent-wash: rgb(44 104 73 / .1);

  --display: "Libre Caslon Display", "Iowan Old Style", Georgia, serif;
  --text: "Libre Franklin", "Franklin Gothic Book", "Segoe UI", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, Consolas, monospace;

  --row: 2.25rem;
  --margin: 5.5rem;
  --money: 8.5rem;
  --ease-out: cubic-bezier(.23, 1, .32, 1);
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --paper: #151b18;
    --paper-deep: #1d2621;
    --ink: #e3e8dc;
    --ink-soft: #a0ada4;
    --rule: #26332c;
    --rule-strong: #3f5548;
    --accent: #8ac7a2;
    --signal: #f08276;
    --signal-wash: rgb(240 130 118 / .1);
    --accent-wash: rgb(138 199 162 / .1);
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--paper); color: var(--ink);
  font: 400 1rem/1.6 var(--text); font-feature-settings: "tnum" 1;
}
::selection { background: var(--accent); color: var(--paper); }
a { color: var(--accent); text-underline-offset: .2em; text-decoration-thickness: 1px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }

.wrap { max-width: 72rem; margin: 0 auto; padding-inline: 16px; }
.skip { position: absolute; left: 16px; top: -3rem; background: var(--ink); color: var(--paper); padding: .5rem .75rem; z-index: 2; }
.skip:focus { top: .75rem; }

/* Masthead: the book's cover label. */
.masthead {
  display: grid; grid-template-columns: minmax(0, auto) minmax(0, 38rem); gap: 1rem 3.5rem; align-items: end;
  padding-top: 3.5rem; padding-bottom: 2rem;
  border-bottom: 3px double var(--rule-strong);
}
.wordmark {
  font: 400 clamp(4rem, 11vw, 7.5rem)/.9 var(--display); letter-spacing: -.02em; margin: 0;
}
.lede { font-size: 1.075rem; line-height: 1.6; margin: 0 0 .75rem; text-wrap: pretty; max-width: 62ch; }
.note { color: var(--ink-soft); font-size: .875rem; margin: 0; text-wrap: pretty; }

/* Index tabs cut into the top edge of the page. */
.tabs { display: flex; flex-wrap: wrap; gap: .375rem; margin: 2.5rem 0 0; position: relative; }
.tabs button {
  font: 500 .9375rem/1 var(--text); color: var(--ink);
  padding: .8rem 1.05rem .75rem; min-height: 2.75rem;
  background: var(--paper-deep); border: 1px solid var(--rule-strong); border-bottom-color: transparent;
  border-radius: 3px 3px 0 0; cursor: pointer; position: relative;
  touch-action: manipulation; -webkit-tap-highlight-color: transparent;
  transition: background-color 160ms ease, color 160ms ease, transform 120ms var(--ease-out);
}
.tabs button.surprise { color: var(--signal); }
@media (hover: hover) and (pointer: fine) {
  .tabs button:hover:not(:disabled) { background: var(--paper); }
}
.tabs button:active:not(:disabled) { transform: translateY(1px) scale(.98); }
.tabs button[aria-pressed="true"] {
  background: var(--paper); box-shadow: 0 1px 0 0 var(--paper); z-index: 1; font-weight: 600;
}
.tabs button[aria-pressed="true"]::before {
  content: ""; position: absolute; left: -1px; right: -1px; top: -1px; height: 3px; background: var(--ink);
  border-radius: 3px 3px 0 0;
}
.tabs button.surprise[aria-pressed="true"]::before { background: var(--signal); }
.tabs button:disabled { cursor: progress; opacity: .55; }

/* The book: caption, the ruled page, and the figures column. */
.book { border-top: 1px solid var(--rule-strong); padding-top: 1.5rem; }
.folio { display: grid; grid-template-columns: minmax(0, 14rem) minmax(0, 1fr); gap: .25rem 2rem; align-items: baseline; margin-bottom: 1.25rem; }
.folio h2 { font: 400 2rem/1.1 var(--display); margin: 0; letter-spacing: -.01em; text-wrap: balance; }
.caption { margin: 0; max-width: 64ch; min-height: 3.2em; text-wrap: pretty; transition: opacity 200ms ease; }
.caption.swap { opacity: 0; }

.spread { display: grid; grid-template-columns: minmax(0, 1fr) 15rem; gap: 2rem; align-items: start; }

.page {
  position: relative; min-height: calc(var(--row) * 9);
  background:
    linear-gradient(to right, transparent calc(var(--margin) - 5px), color-mix(in srgb, var(--signal) 55%, transparent) calc(var(--margin) - 5px) calc(var(--margin) - 4px), transparent calc(var(--margin) - 4px) calc(var(--margin) - 2px), color-mix(in srgb, var(--signal) 55%, transparent) calc(var(--margin) - 2px) calc(var(--margin) - 1px), transparent calc(var(--margin) - 1px)),
    linear-gradient(to left, transparent calc(var(--money) - 1px), var(--rule-strong) calc(var(--money) - 1px) var(--money), transparent var(--money) calc(var(--money) * 2 - 1px), var(--rule-strong) calc(var(--money) * 2 - 1px) calc(var(--money) * 2), transparent calc(var(--money) * 2)),
    repeating-linear-gradient(to bottom, transparent 0 calc(var(--row) - 1px), var(--rule) calc(var(--row) - 1px) var(--row));
  border-bottom: 1px solid var(--rule-strong);
}
.page.plain {
  background:
    linear-gradient(to right, transparent calc(var(--margin) - 5px), color-mix(in srgb, var(--signal) 55%, transparent) calc(var(--margin) - 5px) calc(var(--margin) - 4px), transparent calc(var(--margin) - 4px) calc(var(--margin) - 2px), color-mix(in srgb, var(--signal) 55%, transparent) calc(var(--margin) - 2px) calc(var(--margin) - 1px), transparent calc(var(--margin) - 1px)),
    repeating-linear-gradient(to bottom, transparent 0 calc(var(--row) - 1px), var(--rule) calc(var(--row) - 1px) var(--row));
}

/* The chain's reasons wrap to any height, so that page keeps only the margin rule. */
.page.unruled {
  background: linear-gradient(to right, transparent calc(var(--margin) - 5px), color-mix(in srgb, var(--signal) 55%, transparent) calc(var(--margin) - 5px) calc(var(--margin) - 4px), transparent calc(var(--margin) - 4px) calc(var(--margin) - 2px), color-mix(in srgb, var(--signal) 55%, transparent) calc(var(--margin) - 2px) calc(var(--margin) - 1px), transparent calc(var(--margin) - 1px));
}

.row {
  display: grid; grid-template-columns: var(--margin) minmax(0, 1fr) var(--money) var(--money);
  height: var(--row); align-items: center; position: relative;
}
.row > * { padding-inline: .75rem; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.row .ref { font: 400 .75rem/1 var(--mono); color: var(--ink-soft); padding-left: .5rem; padding-right: .5rem; }
.row .fig { font: 400 .9375rem/1 var(--mono); text-align: right; font-variant-numeric: tabular-nums; }
.row.head > * { font: 600 .75rem/1 var(--text); letter-spacing: .04em; color: var(--ink-soft); }
.row.head .fig { font-family: var(--text); }
.row.head { border-bottom: 1px solid var(--rule-strong); }
.row.earlier { color: var(--ink-soft); }
.row.lit { background: var(--accent-wash); }
.row.lost .part::after { content: "reply lost"; margin-left: .6rem; font: 500 .75rem/1 var(--text); color: var(--signal); }
.row.ghost { color: var(--ink-soft); }
.row.ghost .part, .row.ghost .fig { opacity: .75; }
.row .strike {
  position: absolute; left: var(--margin); right: 0; top: 50%; height: 1.5px; background: var(--signal);
  transform: scaleX(0); transform-origin: left center; padding: 0;
}
.row .strike.on { transform: scaleX(1); transition: transform 520ms var(--ease-out); }

.entries { position: relative; }
.stamp {
  position: absolute; right: .75rem; left: auto; max-width: min(26rem, calc(100% - var(--margin) - 1.5rem));
  border: 1.5px solid var(--signal); color: var(--signal); border-radius: 2px;
  padding: .45rem .7rem; font: 500 .8125rem/1.35 var(--text);
  transform: rotate(-1.5deg); background: var(--paper);
}
.stamp b { font-weight: 600; }
.stamp code { font: 400 .75rem var(--mono); }

.totals { border-top: 1px solid var(--ink); }
.totals .row:last-child { border-bottom: 3px double var(--ink); }
.totals .part { font-weight: 600; }
.totals .fig { font-weight: 500; }
.row.diff .fig { color: var(--accent); }

.recon { margin-top: calc(var(--row) * 1); }
.recon .row { grid-template-columns: var(--margin) minmax(0, 1fr) var(--money); }
.recon .row.done .fig:last-child { color: var(--accent); }

/* Running figures in the side column. */
.figures { display: grid; gap: 1.1rem; padding-top: .25rem; }
.figure { border-bottom: 1px solid var(--rule); padding-bottom: .9rem; }
.figure .label { font-size: .8125rem; color: var(--ink-soft); }
.figure .value { font: 400 1.625rem/1.15 var(--mono); font-variant-numeric: tabular-nums; letter-spacing: -.01em; }
.figure .value.neg { color: var(--signal); }
.figure .value.good { color: var(--accent); }
.figure .sub { font-size: .8125rem; color: var(--ink-soft); }

/* Break it: the tape of one fault run, second by second. */
.tape-wrap { padding: calc(var(--row) * .5) .75rem 0 calc(var(--margin) + .5rem); }
.tape {
  position: relative; height: 11rem; display: flex; align-items: flex-end; gap: 2px;
  border-bottom: 1px solid var(--ink); cursor: ew-resize; touch-action: pan-y; user-select: none;
}
.tape .sec { flex: 1 1 0; height: 100%; display: flex; flex-direction: column-reverse; transform: scaleY(0); transform-origin: bottom; }
.tape .sec.on { transform: scaleY(1); transition: transform 260ms var(--ease-out); }
.tape .ok { background: var(--ink); opacity: .82; }
.tape .retry { background: var(--signal); transition: background-color 900ms ease; }
.tape.settled .retry { background: var(--rule-strong); }
.tape .mark { position: absolute; top: -.25rem; bottom: 0; width: 0; border-left: 1.5px dashed var(--signal); pointer-events: none; }
.tape .mark.heal { border-left-color: var(--accent); }
.tape .mark span {
  position: absolute; top: 0; left: 5px; font: 500 .6875rem/1.2 var(--text); color: var(--signal);
  white-space: nowrap; background: var(--paper); padding: 0 .2rem;
}
.tape .mark.heal span { color: var(--accent); }
.tape .head-line {
  position: absolute; top: -.5rem; bottom: -.5rem; left: 0; width: 2px; background: var(--accent);
  transform: translateX(0); will-change: transform; pointer-events: none;
}
.tape .head-line::after {
  content: ""; position: absolute; left: -5px; bottom: -6px; width: 12px; height: 12px; border-radius: 50%;
  background: var(--accent); border: 2px solid var(--paper);
}
.tape:focus-visible { outline-offset: 6px; }
.axis { display: flex; justify-content: space-between; font: 400 .6875rem/1 var(--mono); color: var(--ink-soft); padding: .45rem 0 0; }
.hint { font-size: .8125rem; color: var(--ink-soft); margin: .6rem 0 0; }
.controls { display: flex; align-items: flex-start; gap: 1rem; }
.controls .hint { flex: 1 1 auto; }
.play {
  flex: none; margin-top: .45rem; font: 500 .8125rem/1 var(--text); color: var(--ink); min-width: 4.5rem;
  padding: .55rem .75rem; background: transparent; border: 1px solid var(--rule-strong); border-radius: 3px;
  cursor: pointer; touch-action: manipulation; transition: background-color 160ms ease, transform 120ms var(--ease-out);
}
@media (hover: hover) and (pointer: fine) { .play:hover { background: var(--paper-deep); } }
.play:active { transform: scale(.97); }

.journal { list-style: none; margin: calc(var(--row) * .5) 0 0; padding: 0; }
.journal li {
  display: grid; grid-template-columns: var(--margin) minmax(0, 1fr); height: var(--row); align-items: center;
  color: var(--ink-soft); opacity: .45; transition: opacity 240ms ease, color 240ms ease;
}
.journal li > * { padding-inline: .75rem; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.journal .t { font: 400 .75rem/1 var(--mono); text-align: right; padding-right: 1rem; }
.journal li.past { opacity: 1; color: var(--ink); }
.journal li.past.fault { color: var(--signal); }
.journal li.now { background: var(--signal-wash); }

.summary { margin-top: calc(var(--row) * .5); }
.summary .row { grid-template-columns: var(--margin) minmax(0, 1fr) var(--money); }
.summary .row:last-child { border-bottom: 3px double var(--ink); }
.summary .zero { color: var(--accent); }

/* Flag it: the account chain drawn down the margin, reasons written beside each hop. */
.chain { list-style: none; margin: 0; padding: calc(var(--row) * .5) 0 var(--row); }
.hop { display: grid; grid-template-columns: var(--margin) minmax(0, 1fr); column-gap: 0; min-height: calc(var(--row) * 3); }
.hop .rail { position: relative; display: flex; justify-content: center; }
.hop .node {
  position: relative; z-index: 1; margin-top: .55rem; width: 1.1rem; height: 1.1rem; border-radius: 50%;
  border: 1.5px solid var(--ink-soft); background: var(--paper);
  transition: background-color 300ms ease, border-color 300ms ease;
}
.hop .node::after {
  content: ""; position: absolute; inset: -6px; border-radius: 50%; border: 1.5px solid var(--signal);
  opacity: 0; transform: scale(.6);
}
.hop.flagged .node { background: var(--signal); border-color: var(--signal); }
.hop.flagged .node::after { animation: ring 700ms var(--ease-out) 1; }
.hop .edge {
  position: absolute; top: 1.65rem; bottom: -.55rem; left: 50%; width: 1.5px; margin-left: -.75px;
  background: var(--signal); transform: scaleY(0); transform-origin: top;
}
.hop .edge.on { transform: scaleY(1); transition: transform 700ms var(--ease-out); }
.hop:last-child .edge { display: none; }
.hop .body { padding: .3rem .75rem 1rem; opacity: 0; transform: translateY(6px); }
.hop .body.on { opacity: 1; transform: none; transition: opacity 320ms ease, transform 420ms var(--ease-out); }
.hop .who { font: 400 1.35rem/1.2 var(--display); }
.hop .what { font-size: .9375rem; margin: .15rem 0 .35rem; }
.hop .what .fig { font-family: var(--mono); }
.hop .score { font: 500 .8125rem/1.3 var(--text); color: var(--ink-soft); }
.hop.flagged .score { color: var(--signal); }
.hop ul { margin: .35rem 0 0; padding: 0; list-style: none; font-size: .875rem; }
.hop li { display: flex; justify-content: space-between; gap: 1rem; max-width: 30rem; border-bottom: 1px dotted var(--rule-strong); padding: .15rem 0; }
.hop li .pts { font-family: var(--mono); white-space: nowrap; }
.hop .because { font-size: .875rem; color: var(--ink-soft); margin: .4rem 0 0; max-width: 34rem; }
.usual { display: flex; flex-wrap: wrap; gap: .4rem .9rem; font-size: .8125rem; color: var(--ink-soft); margin-top: .35rem; }
.usual span::before {
  content: ""; display: inline-block; width: .55rem; height: .55rem; border-radius: 50%;
  border: 1.5px solid var(--rule-strong); margin-right: .35rem; vertical-align: -.02rem;
}
@keyframes ring { 0% { opacity: .9; transform: scale(.6); } 100% { opacity: 0; transform: scale(1.5); } }

/* What went over the wire. */
.wire { margin-top: 1.75rem; border-top: 1px solid var(--rule-strong); padding-top: .9rem; }
.wire summary { cursor: pointer; font-weight: 500; color: var(--ink-soft); width: max-content; max-width: 100%; }
.wire summary:hover { color: var(--ink); }
.wire ol { padding-left: 1.4rem; margin: .75rem 0 0; }
.wire li { margin: .45rem 0; font-size: .8125rem; color: var(--ink-soft); }
.wire code { font: 400 .78rem/1.5 var(--mono); color: var(--ink); overflow-wrap: anywhere; }
.wire .lost { color: var(--signal); font-weight: 600; }

/* Trial balance: the headline numbers, each read from eval/. */
.trial { margin-top: 4.5rem; }
.trial h2 { font: 400 2rem/1.1 var(--display); margin: 0 0 1rem; letter-spacing: -.01em; text-wrap: balance; }
.trial-list { margin: 0; border-top: 1px solid var(--ink); }
.trial-list > div {
  display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: .15rem 1.5rem; align-items: baseline;
  padding: .9rem 0; border-bottom: 1px solid var(--rule);
}
.trial-list > div:last-child { border-bottom: 3px double var(--ink); }
.trial-list dt { font-weight: 500; }
.trial-list dd { margin: 0; font: 400 1.5rem/1.2 var(--mono); text-align: right; font-variant-numeric: tabular-nums; }
.trial-list .was { grid-column: 1 / -1; font-size: .875rem; color: var(--ink-soft); margin: 0; }
.trial .note { margin-top: .9rem; }
.trial .note code { font: 400 .8125rem var(--mono); }

.colophon { padding-top: 3rem; padding-bottom: 3rem; color: var(--ink-soft); font-size: .875rem; }

.error { margin: 1rem 0 0 calc(var(--margin) + .5rem); color: var(--signal); }
.error button {
  font: 500 .875rem var(--text); margin-left: .5rem; padding: .45rem .8rem; border: 1px solid currentColor;
  background: transparent; color: inherit; border-radius: 3px; cursor: pointer;
}

/* The book narrows: the side column moves under the page, the margin and money columns tighten. */
@media (max-width: 960px) {
  .spread { grid-template-columns: minmax(0, 1fr); }
  .figures { grid-template-columns: repeat(auto-fit, minmax(9rem, 1fr)); gap: 1rem 1.5rem; }
}
@media (max-width: 720px) {
  :root { --margin: 2.75rem; --money: 4.6rem; }
  .masthead { grid-template-columns: minmax(0, 1fr); padding-top: 2rem; }
  .folio { grid-template-columns: minmax(0, 1fr); }
  .folio h2 { font-size: 1.625rem; }
  .row > * { padding-inline: .45rem; }
  .row .ref { font-size: .625rem; padding-inline: .3rem; }
  .row .fig { font-size: .8125rem; }
  .row .part { font-size: .875rem; }
  .row.lost .part::after { content: "lost"; margin-left: .4rem; }
  .tape { height: 9rem; }
  .tape .mark span { display: none; }
  .tabs { margin-bottom: 1rem; }
  .tabs button { flex: 1 1 auto; padding: .75rem .8rem .7rem; font-size: .875rem; border-bottom-color: var(--rule-strong); border-radius: 3px; }
  .tabs button[aria-pressed="true"] { box-shadow: none; }
  .figure .value { font-size: 1.3rem; }
  .trial-list dd { font-size: 1.2rem; }
  .stamp { right: .25rem; }
  .journal .t { font-size: .625rem; padding-inline: .15rem .4rem; }
  .summary .row { grid-template-columns: var(--margin) minmax(0, 1fr) auto; }
  .summary .part { font-size: .875rem; }
}

@media (prefers-reduced-motion: reduce) {
  .tabs button, .tape .sec.on, .row .strike.on, .hop .edge.on, .hop .body.on, .journal li, .tape .retry { transition-duration: 1ms; }
  .hop.flagged .node::after { animation: none; }
  .hop .body { transform: none; }
}