/* Signalbox — shared design system for the mockups.
   Metaphor: the human is a signaller, agents are trains, the codebase is track.
   Plan:
     ground  #EEF1EF  enamel panel grey-green
     surface #FFFFFF
     ink     #16201C
     muted   #56645E
     line    #D3DBD7
     accent  #1D4F91  rail blue (links, primary action, selection)
     lamp    #E9B949  route-set lamp (highlights in diagrams only)
     status  clear #1E7F4A · caution #B57A00 · stop #C0352A
   Type: Barlow Semi Condensed (headings, labels) · IBM Plex Sans (body) · IBM Plex Mono (code, ids, numbers)
*/
@import url('https://fonts.googleapis.com/css2?family=Barlow+Semi+Condensed:wght@500;600;700&family=IBM+Plex+Mono:wght@400;500;600&family=IBM+Plex+Sans:ital,wght@0,400;0,500;0,600;1,400&display=swap');

:root {
  --ground: #EEF1EF;
  --surface: #FFFFFF;
  --surface-2: #F6F8F7;
  --ink: #16201C;
  --muted: #56645E;
  --faint: #8A9893;
  --line: #D3DBD7;
  --line-strong: #B5C1BB;
  --accent: #1D4F91;
  --accent-ink: #FFFFFF;
  --accent-soft: #E3EBF6;
  --lamp: #E9B949;
  --lamp-soft: #FBF1D6;
  --clear: #1E7F4A;
  --clear-soft: #E1F2E8;
  --caution: #B57A00;
  --caution-soft: #FAEFD5;
  --stop: #C0352A;
  --stop-soft: #F8E2DF;
  --track: #2B3632;          /* track lines in diagrams */
  --code-bg: #F6F8F7;
  --shadow: 0 1px 2px rgba(22, 32, 28, .06), 0 4px 16px rgba(22, 32, 28, .05);
  --radius: 6px;
  --f-head: 'Barlow Semi Condensed', 'Arial Narrow', system-ui, sans-serif;
  --f-body: 'IBM Plex Sans', system-ui, -apple-system, 'Segoe UI', sans-serif;
  --f-mono: 'IBM Plex Mono', ui-monospace, 'SFMono-Regular', Menlo, monospace;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --ground: #0E1311;
    --surface: #151C19;
    --surface-2: #1A2320;
    --ink: #E4EBE8;
    --muted: #9AAAA3;
    --faint: #6B7A74;
    --line: #26312D;
    --line-strong: #364540;
    --accent: #8DB2F2;
    --accent-ink: #0E1311;
    --accent-soft: #1A2740;
    --lamp: #F2CF6B;
    --lamp-soft: #3A3218;
    --clear: #4CC285;
    --clear-soft: #15301F;
    --caution: #E2A93A;
    --caution-soft: #362A12;
    --stop: #EF6B5E;
    --stop-soft: #3A1A17;
    --track: #C9D4CF;
    --code-bg: #111815;
    --shadow: 0 1px 2px rgba(0, 0, 0, .4);
    color-scheme: dark;
  }
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--ground);
  color: var(--ink);
  font: 400 15px/1.55 var(--f-body);
}
a { color: var(--accent); text-underline-offset: 2px; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 3px; }
img, svg, canvas { max-width: 100%; }
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
}

/* ---------- shell ---------- */
.topbar {
  display: flex; align-items: center; gap: 16px; flex-wrap: wrap;
  padding: 10px 16px;
  background: var(--surface);
  border-bottom: 1px solid var(--line);
}
.brand {
  display: flex; align-items: center; gap: 8px;
  font: 700 18px/1 var(--f-head); letter-spacing: .02em; color: var(--ink); text-decoration: none;
}
.brand-mark { width: 22px; height: 22px; flex: none; }
.crumb { font: 500 13px/1 var(--f-mono); color: var(--muted); min-width: 0; overflow-wrap: anywhere; }
.crumb b { color: var(--ink); font-weight: 600; }
.topbar .spacer { flex: 1; }
.fleet-count { font: 500 12px/1 var(--f-mono); color: var(--muted); display: flex; align-items: center; gap: 6px; }

.nav {
  display: flex; gap: 2px; overflow-x: auto;
  padding: 0 16px; background: var(--surface); border-bottom: 1px solid var(--line);
  scrollbar-width: none;
}
.nav::-webkit-scrollbar { display: none; }
.nav a {
  flex: none; padding: 10px 12px 9px;
  font: 600 14px/1 var(--f-head); letter-spacing: .03em; text-transform: uppercase;
  color: var(--muted); text-decoration: none; border-bottom: 2px solid transparent;
}
.nav a:hover { color: var(--ink); }
.nav a[aria-current="page"] { color: var(--ink); border-bottom-color: var(--accent); }
.nav .was { font: 400 11px/1 var(--f-body); text-transform: none; letter-spacing: 0; color: var(--faint); margin-left: 4px; }

.page { max-width: 1240px; margin: 0 auto; padding: 24px 16px 64px; display: grid; grid-template-columns: minmax(0, 1fr); gap: 24px; }

/* ---------- type ---------- */
h1, h2, h3, h4 { font-family: var(--f-head); line-height: 1.15; margin: 0; text-wrap: balance; letter-spacing: .005em; }
h1 { font-size: 32px; font-weight: 700; }
h2 { font-size: 22px; font-weight: 600; }
h3 { font-size: 17px; font-weight: 600; }
h4 { font-size: 13px; font-weight: 600; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); }
p { margin: 0; max-width: 68ch; }
.lede { font-size: 17px; color: var(--muted); max-width: 68ch; }
.eyebrow { font: 600 12px/1 var(--f-head); text-transform: uppercase; letter-spacing: .1em; color: var(--muted); }
.mono, code { font-family: var(--f-mono); font-size: .9em; }
.num { font-variant-numeric: tabular-nums; }
.muted { color: var(--muted); }
.small { font-size: 13px; }
.stack { display: grid; gap: 12px; align-content: start; }
.stack-sm { display: grid; gap: 6px; align-content: start; }
.row { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
.between { display: flex; gap: 12px; align-items: center; justify-content: space-between; flex-wrap: wrap; }

/* "replaces" note: ties each screen back to the GitHub concept it retires */
.replaces {
  display: inline-flex; gap: 6px; align-items: center;
  font: 500 12px/1 var(--f-mono); color: var(--muted);
  padding: 5px 8px; border: 1px dashed var(--line-strong); border-radius: 4px;
}
.replaces s { color: var(--faint); }

/* ---------- surfaces ---------- */
.card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px; min-width: 0; }
.card-flush { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); min-width: 0; overflow: hidden; }
.card-head { display: flex; gap: 8px; align-items: center; justify-content: space-between; flex-wrap: wrap; padding: 12px 16px; border-bottom: 1px solid var(--line); }
.panel { background: var(--surface-2); border: 1px solid var(--line); border-radius: var(--radius); padding: 12px; min-width: 0; }

/* ---------- status: lamp + pill (shape and colour) ---------- */
.lamp { display: inline-block; width: 9px; height: 9px; border-radius: 50%; background: var(--faint); flex: none; }
.lamp.clear { background: var(--clear); }
.lamp.caution { background: var(--caution); }
.lamp.stop { background: var(--stop); }
.lamp.set { background: var(--lamp); box-shadow: 0 0 0 3px var(--lamp-soft); }
.pill {
  display: inline-flex; align-items: center; gap: 6px;
  font: 600 12px/1 var(--f-head); letter-spacing: .04em; text-transform: uppercase;
  padding: 4px 8px; border-radius: 999px; border: 1px solid var(--line); background: var(--surface-2); color: var(--muted);
  white-space: nowrap;
}
.pill.clear { color: var(--clear); background: var(--clear-soft); border-color: transparent; }
.pill.caution { color: var(--caution); background: var(--caution-soft); border-color: transparent; }
.pill.stop { color: var(--stop); background: var(--stop-soft); border-color: transparent; }
.pill.accent { color: var(--accent); background: var(--accent-soft); border-color: transparent; }
.chip {
  display: inline-flex; align-items: center; gap: 4px;
  font: 500 12px/1.2 var(--f-mono); padding: 3px 6px; border-radius: 4px;
  background: var(--surface-2); border: 1px solid var(--line); color: var(--ink);
}

/* Agent identity: a small square badge, colour from --h (hue) set inline */
.agent { display: inline-flex; align-items: center; gap: 6px; font: 500 13px/1 var(--f-mono); white-space: nowrap; }
.agent::before {
  content: ''; width: 10px; height: 10px; border-radius: 2px; flex: none;
  background: hsl(var(--h, 210) 55% 48%);
}

/* ---------- controls ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 6px; cursor: pointer;
  font: 600 14px/1 var(--f-body); padding: 8px 12px; border-radius: 5px;
  border: 1px solid var(--line-strong); background: var(--surface); color: var(--ink);
  text-decoration: none;
}
.btn:hover { border-color: var(--accent); }
.btn.primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.btn.quiet { border-color: transparent; background: transparent; color: var(--accent); }
.btn.small { font-size: 13px; padding: 6px 9px; }
.seg { display: inline-flex; border: 1px solid var(--line-strong); border-radius: 5px; overflow: hidden; }
.seg button { font: 600 13px/1 var(--f-body); padding: 7px 10px; border: 0; background: var(--surface); color: var(--muted); cursor: pointer; }
.seg button + button { border-left: 1px solid var(--line-strong); }
.seg button[aria-pressed="true"] { background: var(--accent-soft); color: var(--accent); }

/* ---------- tables ---------- */
.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; font-size: 14px; }
th { font: 600 12px/1.2 var(--f-head); text-transform: uppercase; letter-spacing: .06em; color: var(--muted); text-align: left; padding: 8px 12px; border-bottom: 1px solid var(--line); white-space: nowrap; }
td { padding: 9px 12px; border-bottom: 1px solid var(--line); vertical-align: middle; font-variant-numeric: tabular-nums; }
tr:last-child td { border-bottom: 0; }
td.r, th.r { text-align: right; }

/* ---------- code ---------- */
pre, .code {
  margin: 0; font: 400 13px/1.6 var(--f-mono); background: var(--code-bg);
  border: 1px solid var(--line); border-radius: var(--radius); padding: 12px; overflow-x: auto;
}
.diff-add { background: var(--clear-soft); color: var(--ink); display: block; }
.diff-del { background: var(--stop-soft); color: var(--ink); display: block; }

/* ---------- meters ---------- */
.meter { height: 6px; background: var(--line); border-radius: 3px; overflow: hidden; }
.meter > span { display: block; height: 100%; background: var(--accent); }
.meter.clear > span { background: var(--clear); }
.meter.caution > span { background: var(--caution); }
.meter.stop > span { background: var(--stop); }

/* ---------- layout helpers ---------- */
.split { display: grid; grid-template-columns: minmax(0, 1fr) 360px; gap: 24px; align-items: start; }
.cols-2 { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; }
.cols-3 { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
@media (max-width: 960px) {
  .split { grid-template-columns: minmax(0, 1fr); }
  .cols-3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 640px) {
  h1 { font-size: 26px; }
  .cols-2, .cols-3 { grid-template-columns: minmax(0, 1fr); }
  .topbar .crumb { display: none; }
}