:root {
  --paper: #fcfcfa;
  --panel: #f6f6f3;
  --ink: #16181d;
  --ink-2: #4a4f58;
  --ink-3: #767c86;
  --rule: #e3e3df;
  --rule-2: #cdcdc7;
  --accent: #2c5aa0;
  --sans: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --mono: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 15px/1.6 var(--sans);
  -webkit-font-smoothing: antialiased;
}
code, pre { font-family: var(--mono); }

header {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 18px clamp(20px, 5vw, 48px);
  border-bottom: 1px solid var(--rule);
  color: var(--ink-2);
  font: 11px var(--mono);
  letter-spacing: .08em;
}
header .mark { width: 10px; height: 10px; border: 1.5px solid var(--ink); }
header i { color: var(--ink-3); font-style: normal; }
header .rev { margin-left: auto; color: var(--ink-3); }

main {
  max-width: 1020px;
  margin: 0 auto;
  padding: clamp(40px, 6vw, 64px) clamp(20px, 5vw, 48px) 56px;
}

h1 {
  max-width: 26ch;
  margin: 0;
  font-size: clamp(28px, 3.4vw, 38px);
  line-height: 1.2;
  letter-spacing: -.02em;
  font-weight: 600;
}
.lede {
  max-width: 62ch;
  margin: 16px 0 0;
  color: var(--ink-2);
  font-size: 15.5px;
}

/* ---------- diagram ---------- */

.diagram { margin: 44px 0 0; }
.stage {
  display: grid;
  grid-template-columns: minmax(130px, .85fr) minmax(90px, .7fr) minmax(150px, .9fr) minmax(90px, .7fr) minmax(160px, 1fr);
  align-items: center;
  gap: 4px;
  padding: 28px 24px;
  border: 1px solid var(--rule-2);
  background: var(--paper);
}
.stage > * { min-width: 0; }

.zone, .gateway { padding: 16px 14px; border: 1px solid var(--rule); background: var(--panel); }
.gateway { border-color: var(--ink); background: var(--paper); text-align: center; }
.zone h2, .gateway h2 {
  margin: 0 0 12px;
  color: var(--ink);
  font: 10px var(--mono);
  font-weight: 600;
  letter-spacing: .09em;
  text-transform: uppercase;
}
.gateway h2 { font-size: 14px; letter-spacing: 0; text-transform: none; margin-bottom: 6px; }
.gateway code { color: var(--accent); font-size: 12px; }
.zone-note { margin: 12px 0 0; color: var(--ink-3); font-size: 11px; line-height: 1.45; }
.gateway .zone-note { margin-top: 10px; }

.users { list-style: none; display: grid; grid-template-columns: repeat(4, 1fr); gap: 4px; margin: 0; padding: 0; }
.users li {
  padding: 7px 0;
  border: 1px solid var(--rule-2);
  background: var(--paper);
  color: var(--ink-2);
  font: 10px var(--mono);
  text-align: center;
}

.pools { list-style: none; display: grid; gap: 6px; margin: 0; padding: 0; }
.pools li {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 4px 8px;
  padding: 8px 9px;
  border: 1px solid var(--rule-2);
  background: var(--paper);
}
.pools b { font: 12px var(--mono); font-weight: 600; }
.pools span { display: flex; gap: 3px; }
.pools i { width: 8px; height: 14px; border: 1px solid var(--rule-2); background: #eef2f8; }
.pools em { grid-column: 1 / -1; color: var(--ink-3); font: 9px var(--mono); font-style: normal; }

.arrow { display: grid; justify-items: center; gap: 6px; padding: 0 6px; }
.arrow span { position: relative; width: 100%; height: 1px; background: var(--accent); }
.arrow span::after {
  content: "";
  position: absolute;
  right: 0;
  top: -3px;
  border-left: 5px solid var(--accent);
  border-top: 3.5px solid transparent;
  border-bottom: 3.5px solid transparent;
}
.arrow b { color: var(--ink-3); font: 9px/1.3 var(--mono); font-weight: 400; text-align: center; }

figcaption { margin: 12px 0 0; color: var(--ink-3); font: 11px var(--mono); }

/* ---------- notes ---------- */

.notes { margin: 44px 0 0; border-top: 1px solid var(--rule); }
.notes > div {
  display: grid;
  grid-template-columns: 130px 1fr;
  gap: 24px;
  padding: 15px 0;
  border-bottom: 1px solid var(--rule);
}
.notes dt { color: var(--ink); font: 10px var(--mono); font-weight: 600; letter-spacing: .09em; text-transform: uppercase; padding-top: 3px; }
.notes dd { margin: 0; color: var(--ink-2); font-size: 14px; }
.notes code { color: var(--ink); font-size: 12.5px; }

/* ---------- config ---------- */

.config { margin: 44px 0 0; }
.config h2 { margin: 0 0 12px; font-size: 10px; font-family: var(--mono); font-weight: 600; letter-spacing: .09em; text-transform: uppercase; color: var(--ink-3); }
.config pre {
  margin: 0;
  padding: 20px;
  overflow-x: auto;
  border: 1px solid var(--rule-2);
  background: var(--panel);
  color: var(--ink-2);
  font-size: 12.5px;
  line-height: 1.75;
}
.config pre span { color: var(--ink); font-weight: 600; }

footer {
  padding: 18px clamp(20px, 5vw, 48px);
  border-top: 1px solid var(--rule);
  color: var(--ink-3);
  font: 10px var(--mono);
  letter-spacing: .06em;
}

:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

/* ---------- responsive ---------- */

@media (max-width: 860px) {
  .stage { grid-template-columns: 1fr; gap: 0; padding: 22px 18px; }
  .arrow { grid-template-columns: 1fr; padding: 14px 0; gap: 5px; }
  .arrow span { width: 1px; height: 22px; justify-self: center; }
  .arrow span::after {
    right: -3px;
    top: auto;
    bottom: 0;
    border-top: 5px solid var(--accent);
    border-left: 3.5px solid transparent;
    border-right: 3.5px solid transparent;
    border-bottom: 0;
  }
  .users { grid-template-columns: repeat(7, 1fr); }
  .notes > div { grid-template-columns: 1fr; gap: 5px; }
}

@media (max-width: 480px) {
  .users { grid-template-columns: repeat(4, 1fr); }
  .config pre { font-size: 11px; padding: 14px; }
}