/* ===========================================================================
   PRICE ENGINE — docs site
   Dark technical. One accent (--accent). System font stacks only: no external
   font request, so first paint is identical online and offline.
   Colour roles are tokens; nothing below hard-codes a hex outside :root.
   =========================================================================== */

:root {
  --bg:        #0a0d12;
  --surface:   #11161d;
  --surface-2: #161d26;
  --surface-3: #1c2531;
  --border:    #232e3c;
  --border-hi: #33445a;
  --fg:        #e6edf3;
  --fg-dim:    #9fb0c3;
  --fg-faint:  #6d7f93;
  --accent:    #5ad1ff;
  --accent-dim:#1e5f7a;
  --accent-ink:#04121a;

  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  --sans: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;

  --radius: 10px;
  --radius-sm: 6px;
  --radius-lg: 14px;

  --duration: 150ms;
  --ease: cubic-bezier(0.4, 0, 0.2, 1);

  --sidebar-w: 15rem;
  --measure: 68ch;
}

*, *::before, *::after { box-sizing: border-box; }
html, body { overflow-x: clip; }
html { color-scheme: dark; scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration-color: var(--accent-dim); text-underline-offset: 3px; }
a:hover { text-decoration-color: var(--accent); }

:where(a, button, [tabindex]):focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

h1, h2, h3, h4 { line-height: 1.15; margin: 0; overflow-wrap: anywhere; min-width: 0; }
p { margin: 0 0 1rem; }
p:last-child { margin-bottom: 0; }
code, kbd, pre, samp { font-family: var(--mono); }
.num { font-variant-numeric: tabular-nums; }

/* ---- layout -------------------------------------------------------------- */
.layout { display: grid; grid-template-columns: var(--sidebar-w) minmax(0, 1fr); }

.sidebar {
  position: sticky; top: 0; align-self: start;
  height: 100vh; overflow-y: auto;
  border-right: 1px solid var(--border);
  background: var(--surface);
  padding: 1.75rem 1.25rem;
}
.sidebar .brand { display: block; font-family: var(--mono); font-size: 0.875rem; letter-spacing: 0.04em; color: var(--fg); text-decoration: none; }
.sidebar .brand b { color: var(--accent); }
.sidebar .brand span { display: block; color: var(--fg-faint); font-size: 0.75rem; letter-spacing: 0.1em; text-transform: uppercase; margin-top: 0.35rem; }
.sidebar nav { margin-top: 2rem; }
.sidebar nav ol { list-style: none; margin: 0; padding: 0; counter-reset: nav; }
.sidebar nav li { counter-increment: nav; }
.sidebar nav a {
  display: grid; grid-template-columns: 1.5rem 1fr; gap: 0.5rem;
  padding: 0.4rem 0.5rem; border-radius: var(--radius-sm);
  font-size: 0.8125rem; color: var(--fg-dim); text-decoration: none;
  transition: color var(--duration) var(--ease), background-color var(--duration) var(--ease);
}
.sidebar nav a::before { content: counter(nav, decimal-leading-zero); font-family: var(--mono); color: var(--fg-faint); font-size: 0.75rem; }
.sidebar nav a:hover { background: var(--surface-2); color: var(--fg); }
.sidebar .meta { margin-top: 2rem; padding-top: 1.25rem; border-top: 1px solid var(--border); font-family: var(--mono); font-size: 0.6875rem; color: var(--fg-faint); line-height: 1.8; }

main { min-width: 0; padding: 0 clamp(1.25rem, 4vw, 3.5rem) 5rem; }
section { padding: 4rem 0 0; scroll-margin-top: 1.5rem; }
section > .inner { max-width: 62rem; }

.eyebrow {
  font-family: var(--mono); font-size: 0.6875rem; letter-spacing: 0.18em;
  text-transform: uppercase; color: var(--accent); margin: 0 0 0.75rem;
}
h2 { font-size: clamp(1.35rem, 3vw, 1.75rem); letter-spacing: -0.01em; margin-bottom: 0.75rem; }
h3 { font-size: 1rem; margin-bottom: 0.35rem; }
.lede { color: var(--fg-dim); max-width: var(--measure); margin-bottom: 2rem; }
.prose { max-width: var(--measure); color: var(--fg-dim); }
.prose b, .prose strong { color: var(--fg); font-weight: 600; }

/* ---- 1. hero ------------------------------------------------------------- */
.hero { padding-top: 4.5rem; }
.hero h1 { font-size: clamp(2.1rem, 6vw, 3.4rem); letter-spacing: -0.035em; margin-bottom: 1rem; }
.hero h1 em { font-style: normal; color: var(--accent); }
.hero .pitch { font-size: clamp(1rem, 2.2vw, 1.2rem); color: var(--fg-dim); max-width: 46ch; margin-bottom: 1.75rem; }
.tags { display: flex; flex-wrap: wrap; gap: 0.5rem; list-style: none; margin: 0 0 2.5rem; padding: 0; }
.tags li {
  font-family: var(--mono); font-size: 0.75rem; color: var(--fg-dim);
  border: 1px solid var(--border-hi); border-radius: 999px; padding: 0.25rem 0.7rem;
  background: var(--surface);
}
.claims { display: grid; gap: 1rem; grid-template-columns: repeat(auto-fit, minmax(14rem, 1fr)); }
.claim { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 1.35rem; }
.claim .label { font-family: var(--mono); font-size: 0.6875rem; letter-spacing: 0.12em; text-transform: uppercase; color: var(--fg-faint); }
.claim .big { display: block; font-size: clamp(2rem, 6vw, 2.9rem); font-weight: 620; letter-spacing: -0.035em; line-height: 1.05; margin: 0.55rem 0 0.4rem; font-variant-numeric: tabular-nums; color: var(--fg); }
.claim .big small { font-size: 1.1rem; font-weight: 500; color: var(--accent); letter-spacing: 0; }
.claim .why { font-size: 0.8125rem; color: var(--fg-dim); line-height: 1.55; margin: 0; }
.prov { margin-top: 1.75rem; font-family: var(--mono); font-size: 0.75rem; color: var(--fg-faint); border-left: 2px solid var(--accent-dim); padding-left: 0.9rem; line-height: 1.9; overflow-wrap: anywhere; }

/* ---- 2. what it does ----------------------------------------------------- */
.two-col { display: grid; gap: 1.25rem; grid-template-columns: repeat(auto-fit, minmax(17rem, 1fr)); margin-top: 1.5rem; }
.panel { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 1.35rem; }
.panel h3 { color: var(--fg); }
.panel p { font-size: 0.875rem; color: var(--fg-dim); }
.kicker { font-family: var(--mono); font-size: 0.6875rem; text-transform: uppercase; letter-spacing: 0.12em; color: var(--accent); }

/* ---- 3. architecture ----------------------------------------------------- */
.arch { display: grid; gap: 0.75rem; margin-top: 1.5rem; }
.arch-stage { display: grid; grid-template-columns: 9.5rem minmax(0, 1fr); gap: 1rem; align-items: stretch; }
.arch-stage > .stage-label {
  font-family: var(--mono); font-size: 0.75rem; color: var(--fg-faint);
  text-transform: uppercase; letter-spacing: 0.1em; padding-top: 1rem;
  border-right: 1px dashed var(--border-hi); padding-right: 1rem;
}
.node {
  background: var(--surface); border: 1px solid var(--border);
  border-left: 3px solid var(--accent-dim);
  border-radius: var(--radius); padding: 0.85rem 1rem;
}
.node.is-accent { border-left-color: var(--accent); }
.node .fn { font-family: var(--mono); font-size: 0.8125rem; color: var(--accent); }
.node .desc { font-size: 0.8125rem; color: var(--fg-dim); margin: 0.2rem 0 0; line-height: 1.5; }
.node-row { display: grid; gap: 0.75rem; grid-template-columns: repeat(auto-fit, minmax(13rem, 1fr)); }
.flow-arrow { color: var(--fg-faint); font-family: var(--mono); font-size: 0.8125rem; text-align: center; padding: 0.1rem 0; }
.arch-note {
  margin-top: 1.25rem; background: var(--surface-2); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1rem 1.15rem; font-size: 0.875rem; color: var(--fg-dim);
  max-width: var(--measure);
}
.arch-note b { color: var(--fg); }

/* ---- 4. real output ------------------------------------------------------ */
.runstamp {
  display: inline-flex; align-items: center; gap: 0.5rem; flex-wrap: wrap;
  font-family: var(--mono); font-size: 0.75rem; color: var(--fg-dim);
  background: var(--surface-2); border: 1px solid var(--border-hi);
  border-radius: 999px; padding: 0.3rem 0.85rem; margin-bottom: 1.5rem;
}
.runstamp .dot { width: 7px; height: 7px; border-radius: 50%; background: var(--accent); flex: none; }

.subhead { font-family: var(--mono); font-size: 0.75rem; letter-spacing: 0.12em; text-transform: uppercase; color: var(--fg-faint); margin: 2.5rem 0 0.9rem; }

.charts { display: grid; gap: 1rem; grid-template-columns: repeat(auto-fit, minmax(18rem, 1fr)); }
.chart { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 1.35rem; }
.chart h3 { font-size: 0.9375rem; }
.chart .unit { font-family: var(--mono); font-size: 0.6875rem; color: var(--fg-faint); }
.bars { margin-top: 1.15rem; display: grid; gap: 0.85rem; }
.bar-row { display: grid; grid-template-columns: 6rem minmax(0, 1fr); gap: 0.75rem; align-items: center; }
.bar-row .who { font-size: 0.8125rem; color: var(--fg-dim); }
.bar-track { background: var(--surface-3); border-radius: var(--radius-sm); }
.bar-fill {
  height: 2rem; border-radius: var(--radius-sm); display: flex; align-items: center;
  justify-content: flex-end; padding-right: 0.6rem; min-width: 5.5rem;
  font-family: var(--mono); font-size: 0.8125rem; font-variant-numeric: tabular-nums;
}
.bar-fill[data-who="lgbm"] { background: var(--accent); color: var(--accent-ink); }
.bar-fill[data-who="sk"]   { background: var(--surface-3); border: 1px solid var(--border-hi); color: var(--fg-dim); }
.verdict { margin-top: 1.25rem; background: var(--surface-2); border: 1px solid var(--border); border-left: 3px solid var(--accent); border-radius: var(--radius); padding: 1rem 1.15rem; font-size: 0.875rem; color: var(--fg-dim); max-width: var(--measure); }
.verdict b { color: var(--fg); font-variant-numeric: tabular-nums; }

.imp { display: grid; gap: 0.5rem; }
.imp-row { display: grid; grid-template-columns: 7.5rem minmax(0, 1fr) 3.25rem; gap: 0.75rem; align-items: center; }
.imp-row .f { font-family: var(--mono); font-size: 0.8125rem; color: var(--fg-dim); }
.imp-row .v { font-family: var(--mono); font-size: 0.8125rem; text-align: right; color: var(--fg-faint); font-variant-numeric: tabular-nums; }
.imp-track { background: var(--surface-3); border-radius: var(--radius-sm); height: 1.25rem; }
.imp-fill { height: 100%; background: var(--accent); border-radius: var(--radius-sm); min-width: 2px; opacity: 0.85; }

.table-scroll { overflow-x: auto; border: 1px solid var(--border); border-radius: var(--radius-lg); background: var(--surface); }
table { border-collapse: collapse; width: 100%; font-size: 0.8125rem; }
th, td { padding: 0.55rem 0.8rem; text-align: right; white-space: nowrap; }
th { font-family: var(--mono); font-size: 0.6875rem; font-weight: 500; text-transform: uppercase; letter-spacing: 0.08em; color: var(--fg-faint); border-bottom: 1px solid var(--border); background: var(--surface-2); }
td { font-variant-numeric: tabular-nums; color: var(--fg-dim); }
td.strong { color: var(--fg); }
tbody tr + tr td { border-top: 1px solid var(--border); }

/* Diverging delta: one hue. Direction is position (left = under, right = over),
   magnitude is length. No second colour needed to read the sign. */
.delta-cell { min-width: 11rem; }
.delta { display: grid; grid-template-columns: 1fr 1px 1fr; align-items: center; gap: 0; width: 9.5rem; margin-left: auto; }
.delta .axis { background: var(--border-hi); height: 1.15rem; }
.delta .half { height: 0.55rem; }
.delta .half > i { display: block; height: 100%; background: var(--accent); opacity: 0.9; }
.delta .half.left { display: flex; justify-content: flex-end; border-radius: var(--radius-sm) 0 0 var(--radius-sm); }
.delta .half.left > i { border-radius: var(--radius-sm) 0 0 var(--radius-sm); }
.delta .half.right > i { border-radius: 0 var(--radius-sm) var(--radius-sm) 0; }
.delta-val { font-family: var(--mono); font-variant-numeric: tabular-nums; }
.delta-val::before { content: attr(data-glyph); color: var(--accent); margin-right: 0.35rem; font-size: 0.7em; }
.caption { font-size: 0.8125rem; color: var(--fg-faint); margin-top: 0.9rem; max-width: var(--measure); line-height: 1.6; }
.caption b { color: var(--fg-dim); }

/* ---- terminal ------------------------------------------------------------ */
.terminal { border: 1px solid var(--border); border-radius: var(--radius-lg); overflow: hidden; background: var(--surface); }
.terminal .bar { display: flex; align-items: center; gap: 0.5rem; padding: 0.55rem 0.9rem; background: var(--surface-2); border-bottom: 1px solid var(--border); font-family: var(--mono); font-size: 0.75rem; color: var(--fg-faint); }
.terminal .bar .lights { display: flex; gap: 0.3rem; }
.terminal .bar .lights i { width: 9px; height: 9px; border-radius: 50%; background: var(--border-hi); display: block; }
.terminal .bar .path { margin-left: auto; color: var(--fg-faint); }
.terminal pre { margin: 0; padding: 1rem 1.15rem; overflow-x: auto; font-size: 0.75rem; line-height: 1.55; color: var(--fg-dim); }
.terminal pre b { color: var(--accent); font-weight: 400; }

pre.code { margin: 0; padding: 1.1rem 1.25rem; overflow-x: auto; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); font-size: 0.75rem; line-height: 1.6; color: var(--fg-dim); }
pre.code b { color: var(--accent); font-weight: 400; }

/* ---- 5. decisions -------------------------------------------------------- */
.decisions { display: grid; gap: 0.75rem; margin-top: 1.5rem; }
.decision { display: grid; grid-template-columns: 2rem minmax(0, 1fr); gap: 1rem; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 1rem 1.15rem; }
.decision .n { font-family: var(--mono); font-size: 0.75rem; color: var(--accent); padding-top: 0.15rem; }
.decision .choice { color: var(--fg); font-weight: 600; font-size: 0.9375rem; }
.decision .why { color: var(--fg-dim); font-size: 0.875rem; margin: 0.25rem 0 0; }

/* ---- 6. how to run ------------------------------------------------------- */
.steps { list-style: none; counter-reset: step; padding: 0; margin: 1.5rem 0 0; display: grid; gap: 1rem; }
.steps li { counter-increment: step; display: grid; grid-template-columns: 1.75rem minmax(0, 1fr); gap: 0.9rem; align-items: start; }
.steps li::before { content: counter(step); display: grid; place-items: center; width: 1.75rem; height: 1.75rem; border-radius: 50%; border: 1px solid var(--border-hi); background: var(--surface); color: var(--accent); font-family: var(--mono); font-size: 0.75rem; }
.steps .what { color: var(--fg-dim); font-size: 0.875rem; margin: 0 0 0.45rem; }
.cmd { display: block; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 0.5rem 0.75rem; font-family: var(--mono); font-size: 0.8125rem; color: var(--fg); overflow-x: auto; white-space: pre; }
.cmd .p { color: var(--fg-faint); user-select: none; }

/* ---- 7. code tour -------------------------------------------------------- */
.file { border: 1px solid var(--border); border-radius: var(--radius-lg); background: var(--surface-2); overflow: hidden; margin-top: 1.25rem; }
.file > header { display: flex; align-items: baseline; gap: 0.75rem; flex-wrap: wrap; padding: 0.85rem 1.15rem; border-bottom: 1px solid var(--border); }
.file .name { font-family: var(--mono); font-size: 0.875rem; color: var(--accent); }
.file .role { font-size: 0.8125rem; color: var(--fg-faint); }
.file .why { padding: 0.9rem 1.15rem 0; font-size: 0.875rem; color: var(--fg-dim); max-width: var(--measure); }
.file .excerpt { padding: 0.9rem 1.15rem 1.15rem; }
.file .excerpt pre.code { background: var(--bg); }
.excerpt-label { font-family: var(--mono); font-size: 0.6875rem; color: var(--fg-faint); margin-bottom: 0.4rem; }

footer { margin-top: 4.5rem; padding-top: 1.75rem; border-top: 1px solid var(--border); color: var(--fg-faint); font-size: 0.8125rem; max-width: var(--measure); }

.noscript { margin: 1.5rem 0; background: var(--surface-2); border: 1px solid var(--border-hi); border-left: 3px solid var(--accent); border-radius: var(--radius); padding: 1rem 1.15rem; font-size: 0.875rem; color: var(--fg-dim); }

/* ---- responsive: single column down to 375px ----------------------------- */
@media (max-width: 60rem) {
  .layout { grid-template-columns: minmax(0, 1fr); }
  .sidebar { position: static; height: auto; border-right: 0; border-bottom: 1px solid var(--border); padding: 1.25rem clamp(1.25rem, 4vw, 2rem); }
  .sidebar nav { margin-top: 1rem; }
  .sidebar nav ol { display: flex; flex-wrap: wrap; gap: 0.25rem; }
  .sidebar nav a { padding: 0.3rem 0.6rem; }
  .sidebar .meta { display: none; }
  section { padding-top: 3rem; }
  .arch-stage { grid-template-columns: minmax(0, 1fr); }
  .arch-stage > .stage-label { border-right: 0; border-bottom: 1px dashed var(--border-hi); padding: 0 0 0.4rem; }
}
@media (max-width: 26rem) {
  body { font-size: 15px; }
  .bar-row { grid-template-columns: 4.75rem minmax(0, 1fr); }
  .imp-row { grid-template-columns: 6rem minmax(0, 1fr) 2.75rem; }
  .delta { width: 6.5rem; }
  .claim .big { font-size: 2.1rem; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: 1ms !important; animation-duration: 1ms !important; }
}