:root {
  color-scheme: dark;
  --background: #080a0d;
  --panel: #0e1116;
  --panel-raised: #14181f;
  --ink: #f1eee5;
  --soft: #c9cdd3;
  --muted: #9aa2ac;
  --line: #2a3039;
  --line-bright: #4b5561;
  --accent: #f5bd62;
  --amber: #f5bd62;
  --red: #ff4e42;
  --green: #7dd49d;
  --cyan: #68d7e8;
  --purple: #d5a9ff;
  --pink: #ff9fd0;
  --blue: #7fb2ff;
  --mono: "SFMono-Regular", "Cascadia Code", "Liberation Mono", monospace;
  --sans: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --step: 16px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--background);
  font: 16px/1.6 var(--sans);
  -webkit-font-smoothing: antialiased;
}
p { max-width: 68ch; }
h1, h2, h3 { line-height: 1.25; }
code { font-family: var(--mono); font-size: .92em; color: var(--cyan); }
a { color: inherit; }
[hidden] { display: none !important; }
.visually-hidden {
  position: absolute; width: 1px; height: 1px; overflow: hidden;
  clip-path: inset(50%); white-space: nowrap;
}
.dim { color: var(--muted); font-size: 14px; }
.count { color: var(--muted); font-weight: 400; }

.skip-link {
  position: fixed; top: 8px; left: 8px; z-index: 30; padding: 12px 16px;
  color: var(--background); background: var(--ink); border-radius: 6px;
  transform: translateY(-160%);
}
.skip-link:focus { transform: none; }

.topbar {
  position: sticky; top: 0; z-index: 20;
  display: grid; grid-template-columns: auto 1fr auto; align-items: center; gap: 14px;
  padding: 12px 20px; border-bottom: 1px solid var(--line); background: #0a0c10;
}
.wordmark { color: var(--red); font: 800 12px/1 var(--mono); letter-spacing: .08em; text-decoration: none; }
.topbar-title { color: var(--muted); font-size: 13px; }
.chip {
  padding: 3px 10px; border: 1px solid var(--line-bright); border-radius: 999px;
  color: var(--soft); font: 500 12px/1.6 var(--mono);
}

main { max-width: 900px; margin: 0 auto; padding: 32px 20px 60px; }
section + section { margin-top: 48px; }

/* ----------------------------------------------------------------- hero */
.hero h1 { margin: 0 0 12px; font-size: 32px; letter-spacing: -.02em; }
.hero p { margin: 0 0 10px; font-size: 17px; color: var(--soft); }

/* -------------------------------------------------------------- chooser */
.chooser h2, .graph-wrap h2, .reference h2 { margin: 0 0 6px; font-size: 20px; }
.start { display: flex; flex-wrap: wrap; gap: 10px; margin: 18px 0 22px; }
.start button {
  display: grid; gap: 2px; min-width: 220px; padding: 14px 18px; text-align: left;
  border: 1px solid var(--line-bright); border-radius: 10px; background: var(--panel-raised);
  color: var(--ink); cursor: pointer; font-family: var(--sans);
}
.start button b { font-size: 16px; font-weight: 650; }
.start button span { color: var(--muted); font-size: 13px; }
.start button:hover { border-color: var(--accent); }
.start button[aria-pressed="true"] { border-color: var(--accent); background: #241d10; }

.filter { display: block; margin: 0 0 12px; }
.filter input {
  width: 100%; padding: 12px 14px; color: var(--ink); background: var(--panel);
  border: 1px solid var(--line); border-radius: 8px; font: 15px/1.4 var(--sans);
}
.filter input:focus-visible, button:focus-visible, summary:focus-visible {
  outline: 2px solid var(--accent); outline-offset: 2px;
}

.paths { margin: 0; padding: 0; list-style: none; border-top: 1px solid var(--line); }
.paths li { border-bottom: 1px solid var(--line); }
.paths button {
  display: grid; grid-template-columns: 1fr auto; align-items: baseline; gap: 4px 16px;
  width: 100%; padding: 12px 6px; text-align: left; border: 0; background: transparent;
  color: var(--ink); cursor: pointer; font-family: var(--sans);
}
.paths button:hover { background: var(--panel); }
.paths button[aria-pressed="true"] { background: var(--panel-raised); }
.paths b { font-size: 15px; font-weight: 600; }
.paths .n { color: var(--muted); font: 12px/1.6 var(--mono); white-space: nowrap; }
.paths .why { grid-column: 1 / 2; color: var(--muted); font-size: 14px; }
.paths button[aria-pressed="true"] b { color: var(--accent); }

/* ----------------------------------------------------------------- flow */
.flow-wrap { scroll-margin-top: 80px; }
.flow-head {
  padding: 18px 20px; border: 1px solid var(--line-bright); border-radius: 12px;
  background: var(--panel);
}
.flow-head h2 { margin: 0; font-size: 20px; }
.flow-head .request { margin: 4px 0 10px; color: var(--soft); font: 13px/1.6 var(--mono); word-break: break-word; }
.flow-head .outcome { margin: 0; color: var(--soft); font-size: 15px; }
.flow-head .totals { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 12px; }
.tag {
  padding: 3px 10px; border: 1px solid var(--line-bright); border-radius: 999px;
  color: var(--muted); font: 12px/1.6 var(--mono);
}
.tag strong { color: var(--ink); font-weight: 600; }

.flow { margin: 22px 0 0; padding: 0; list-style: none; }
.step { position: relative; padding-left: 58px; }
.step::before {
  position: absolute; left: 23px; top: 0; bottom: 0; width: 2px;
  background: var(--line); content: "";
}
.step:first-child::before { top: 22px; }
.step:last-child::before { height: 22px; bottom: auto; }
.badge {
  position: absolute; left: 7px; top: 10px; z-index: 1;
  display: grid; place-items: center; width: 34px; height: 34px; border-radius: 50%;
  border: 2px solid var(--line); background: var(--background);
  color: var(--muted); font: 600 13px/1 var(--mono);
}
.step.done .badge { border-color: var(--line-bright); color: var(--soft); }
.step.current .badge { border-color: var(--accent); background: var(--accent); color: #0b0d10; }

.step-head {
  display: flex; align-items: baseline; justify-content: space-between; gap: 12px;
  width: 100%; padding: 14px 2px; border: 0; background: transparent;
  color: var(--ink); cursor: pointer; text-align: left; font-family: var(--sans);
}
.step-head b { font-size: 17px; font-weight: 600; }
.step:not(.current) .step-head b { color: var(--soft); font-weight: 500; }
.step-head .hint { color: var(--muted); font: 12px/1.6 var(--mono); white-space: nowrap; }
.step-head:hover b { color: var(--accent); }

.step-body {
  margin: 0 0 18px; padding: 18px 20px 20px; border: 1px solid var(--line-bright);
  border-radius: 12px; background: var(--panel);
}
.step-body .what { margin: 0 0 10px; font-size: 16px; color: var(--ink); }
.step-body .why {
  margin: 0 0 14px; padding-left: 12px; border-left: 3px solid var(--line-bright);
  color: var(--muted); font-size: 15px;
}
.step-body h3 {
  margin: 18px 0 6px; color: var(--muted);
  font: 600 12px/1.6 var(--mono); letter-spacing: .1em; text-transform: uppercase;
}
.calls { display: flex; flex-wrap: wrap; gap: 8px; }
.call {
  flex: 1 1 240px; border: 1px solid var(--line-bright);
  border-radius: 8px; background: var(--panel-raised);
}
.call.open { flex-basis: 100%; }
.call.flagged { border-color: var(--red); }
.call code { font-size: 14px; }
.call em { color: var(--muted); font-size: 13px; font-style: normal; }
.call.none { border-style: dashed; color: var(--muted); }
.call-head {
  display: grid; grid-template-columns: auto 1fr auto; align-items: baseline; gap: 4px 10px;
  width: 100%; padding: 9px 12px; border: 0; background: transparent; color: var(--ink);
  cursor: pointer; text-align: left; font-family: var(--sans);
}
.call-head:hover code { color: var(--accent); }
.call-head .more { grid-column: 1 / -1; color: var(--muted); font-size: 12px; }
.call-body { padding: 4px 12px 14px; }
.call-body .signature {
  display: block; margin-bottom: 10px; padding: 8px 10px; border-radius: 6px;
  background: #05070a; color: var(--ink); font-size: 13px; white-space: pre-wrap; word-break: break-word;
}
.call-body h4 {
  margin: 14px 0 4px; color: var(--muted);
  font: 600 12px/1.6 var(--mono); letter-spacing: .1em; text-transform: uppercase;
}
.call-body > code {
  display: block; margin-bottom: 3px; padding: 2px 6px; border-radius: 4px;
  background: #05070a; color: var(--soft); font-size: 12.5px; white-space: pre-wrap; word-break: break-word;
}
.call-body > code.call-line { color: var(--accent); }
.call-body p { margin: 0 0 6px; color: var(--soft); font-size: 14px; }
.call-body .variant { margin-top: 10px; }
.call-body .variant-arg { margin: 0 0 2px 12px; color: var(--muted); font-size: 13px; }
table.args { margin-bottom: 6px; }
table.args th, table.args td { padding: 5px 8px; font-size: 13px; }
table.args td:first-child { white-space: nowrap; }
.handling { margin: 0; padding-left: 18px; }
.handling li { margin-bottom: 3px; color: var(--soft); font-size: 13.5px; }
.warn {
  margin: 12px 0; padding: 10px 12px; border: 1px solid var(--red); border-radius: 8px;
  background: #1a0f0e;
}
.warn strong { display: block; margin-bottom: 4px; color: var(--red); font-size: 14px; }
.warn p { margin: 0; color: var(--soft); font-size: 13.5px; }
.site {
  display: block; width: 100%; margin-bottom: 3px; padding: 3px 8px;
  border: 1px solid var(--line); border-radius: 6px; background: transparent;
  color: var(--soft); cursor: pointer; font: 12px/1.6 var(--mono); text-align: left;
}
.site:hover { border-color: var(--accent); color: var(--ink); }
.term {
  border-bottom: 1px dotted var(--line-bright); cursor: help;
}

.inside { display: grid; gap: 8px; margin: 0; padding: 0; list-style: none; }
.inside > li { border: 1px solid var(--line); border-radius: 8px; background: #0b0e13; }
.inside button {
  display: grid; grid-template-columns: 1fr auto; gap: 2px 12px; width: 100%;
  padding: 10px 12px; border: 0; background: transparent; color: var(--ink);
  cursor: pointer; text-align: left; font-family: var(--sans);
}
.inside b { font-size: 15px; font-weight: 600; }
.inside .where { grid-column: 1 / 2; color: var(--muted); font: 12px/1.6 var(--mono); word-break: break-all; }
.inside .calls-n { color: var(--muted); font: 12px/1.6 var(--mono); white-space: nowrap; }
.inside .detail { display: none; padding: 0 12px 12px; }
.inside li.open .detail { display: block; }
.inside .detail p { margin: 0 0 8px; color: var(--soft); font-size: 14px; }
.inside .detail code {
  display: block; margin-bottom: 4px; padding: 6px 8px; border-radius: 4px;
  background: #05070a; color: var(--soft); font-size: 12.5px; white-space: pre-wrap; word-break: break-word;
}
.deadline { margin: 14px 0 0; color: var(--accent); font-size: 14px; }
.continued { margin: 12px 0 0; color: var(--purple); font-size: 14px; }

.flow-controls {
  display: flex; align-items: center; gap: 14px; flex-wrap: wrap;
  margin: 20px 0 0 58px; padding-bottom: 4px;
}
.flow-controls button {
  min-width: 110px; padding: 12px 18px; border: 1px solid var(--line-bright); border-radius: 8px;
  background: var(--panel-raised); color: var(--ink); cursor: pointer; font: 600 15px/1 var(--sans);
}
.flow-controls button:hover:not(:disabled) { border-color: var(--accent); }
.flow-controls button:disabled { opacity: .4; cursor: default; }
.flow-controls .position { color: var(--soft); font: 13px/1.6 var(--mono); }
.flow-controls .bar { flex: 1 1 160px; height: 6px; border-radius: 999px; background: var(--line); overflow: hidden; }
.flow-controls .bar i { display: block; height: 100%; background: var(--accent); }

/* ---------------------------------------------------------------- graph */
.graph-wrap button#graph-toggle {
  margin-top: 14px; padding: 12px 18px; border: 1px solid var(--line-bright); border-radius: 8px;
  background: var(--panel); color: var(--ink); cursor: pointer; font: 600 12px/1 var(--mono); letter-spacing: .06em;
}
.graph { position: relative; margin-top: 16px; border: 1px solid var(--line); border-radius: 10px; background: #0a0c10; overflow: auto; max-height: 70vh; }
.lanes {
  display: grid; grid-template-columns: repeat(8, minmax(190px, 1fr)); gap: 10px;
  padding: 12px 12px 24px; min-width: 1660px;
}
.lane { display: flex; flex-direction: column; gap: 6px; }
.lane-accept { --lane: var(--cyan); }
.lane-handshake { --lane: var(--accent); }
.lane-read { --lane: var(--green); }
.lane-route { --lane: var(--blue); }
.lane-dispatch { --lane: var(--purple); }
.lane-respond { --lane: var(--pink); }
.lane-finish { --lane: var(--red); }
.lane-lifecycle { --lane: var(--line-bright); }
.lane > h3 {
  margin: 0 0 4px; padding-bottom: 6px; border-bottom: 1px solid var(--line);
  color: var(--lane, var(--muted)); font: 600 12px/1.6 var(--mono); letter-spacing: .12em; text-transform: uppercase;
}
.lane-lifecycle { border-left: 1px dashed var(--line); padding-left: 10px; }
.node {
  padding: 8px 10px; border: 1px solid var(--line); border-left: 3px solid var(--lane, var(--line-bright));
  border-radius: 6px; background: var(--panel); color: var(--soft);
  cursor: pointer; font: 13px/1.4 var(--sans); text-align: left;
}
.node:hover { border-color: var(--line-bright); color: var(--ink); }
.node.on-path { border-color: var(--accent); color: var(--ink); }
.node.dimmed { opacity: .3; }
.wires { position: absolute; top: 0; left: 0; pointer-events: none; }
.wires path { fill: none; stroke: var(--line); stroke-width: 1.2; pointer-events: stroke; }
.wires path.on-path { stroke: var(--accent); stroke-width: 2; }
.wires path.dimmed { opacity: .35; }
.wires marker path { fill: var(--line-bright); stroke: none; }

/* ------------------------------------------------------------ reference */
.reference details {
  margin-top: 10px; border: 1px solid var(--line); border-radius: 10px; background: var(--panel);
}
.reference summary {
  padding: 14px 16px; cursor: pointer; font-size: 15px; font-weight: 600;
}
.reference summary:hover { color: var(--accent); }
.panel { padding: 4px 16px 18px; }
.panel h3 { margin: 18px 0 6px; font-size: 15px; }
.panel h3:first-child { margin-top: 6px; }
.panel p { margin: 0 0 10px; color: var(--soft); font-size: 14px; }
.table-scroll { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; font-size: 14px; }
th, td { padding: 8px 10px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
th { color: var(--muted); font: 600 12px/1.6 var(--mono); letter-spacing: .08em; text-transform: uppercase; }
td.num { text-align: right; font-variant-numeric: tabular-nums; }
td code { color: var(--ink); }
.status-row { display: flex; flex-wrap: wrap; gap: 8px; margin: 0 0 12px; }
.status {
  padding: 5px 11px; border: 1px solid var(--line-bright); border-radius: 6px;
  background: var(--panel-raised); font: 13px/1.6 var(--mono);
}
.status.reachable { border-color: var(--green); }
.status.unreachable { color: var(--muted); }
.kind-dot {
  display: inline-block; width: 8px; height: 8px; margin-right: 7px;
  border-radius: 50%; background: var(--muted); vertical-align: middle;
}
.gap { padding: 12px 0; border-top: 1px solid var(--line); }
.gap h3 { margin: 0 0 4px; font-size: 15px; color: var(--accent); }
.gap p { margin: 0; }

.footer { padding: 28px 20px 60px; border-top: 1px solid var(--line); color: var(--muted); font-size: 13px; }
.footer p { max-width: 80ch; margin: 0 0 8px; }

@media (max-width: 720px) {
  main { padding: 22px 16px 50px; }
  .hero h1 { font-size: 26px; }
  .start button { min-width: 100%; }
  .paths button { grid-template-columns: 1fr; }
  .paths .n { justify-self: start; }
  .step { padding-left: 46px; }
  .step::before { left: 17px; }
  .badge { left: 1px; width: 32px; height: 32px; }
  .flow-controls { margin-left: 46px; }
}

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