:root {
  /* Bench instrument: deep green-black enamel, phosphor-brass readout.
     One accent family (signal brass); teal kept for the one live LED. */
  --bg: #0a0f0c;
  --panel: #0e1511;
  --panel2: #121a15;
  --line: #223028;
  --rule: #1a241e;
  --ink: #d8dfd2;
  --dim: #8a978c;
  --faint: #5c6860;
  --brass: #e0a83c;
  --brass-hi: #ffd88a;
  --brass-dim: #6b5320;
  --teal: #00c2a8;
  --teal-dim: #0a5f57;
  --red: #ff6b5e;
  --green: #3ddc84;
  --mono: ui-monospace, "Cascadia Mono", "JetBrains Mono", Menlo, Consolas, monospace;
  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font: 15px/1.55 -apple-system, "Segoe UI", Inter, Roboto, sans-serif;
  min-height: 100vh;
}
::selection { background: #3a2f14; color: var(--brass-hi); }
.bg-grid {
  position: fixed; inset: 0; pointer-events: none; overflow: clip;
  background-image: linear-gradient(#141d1666 1px, transparent 1px),
    linear-gradient(90deg, #141d1666 1px, transparent 1px);
  background-size: 34px 34px;
  mask-image: radial-gradient(ellipse 90% 80% at 50% 0%, black 30%, transparent 90%);
}

/* ---------- site nav ---------- */
.sitenav {
  border-bottom: 1px solid var(--rule);
  background: #0c120ed9;
  position: sticky; top: 0; z-index: 50;
  backdrop-filter: blur(8px);
}
.sitenav-in {
  max-width: 1180px; margin: 0 auto; padding: 10px 30px;
  display: flex; align-items: baseline; gap: 22px; flex-wrap: wrap;
}
.sitenav-brand {
  color: var(--ink); text-decoration: none; font-weight: 800; font-size: 14px;
  letter-spacing: .04em;
}
.sitenav-brand b { color: var(--brass); font-weight: 800; }
.sitenav-links { display: flex; gap: 4px; margin-left: auto; }
.sitenav-links a {
  color: var(--dim); text-decoration: none; font-size: 13.5px; font-weight: 600;
  padding: 6px 12px; border-radius: 8px;
}
.sitenav-links a:hover { color: var(--ink); background: #ffffff10; }
.sitenav-links a[aria-current="page"] { color: var(--brass-hi); background: #e0a83c1a; }

/* ---------- header ---------- */
.topbar {
  display: flex; justify-content: space-between; align-items: center;
  gap: 16px; flex-wrap: wrap;
  padding: 22px 30px 14px; max-width: 1180px; margin: 0 auto;
}
.brand { display: flex; gap: 14px; align-items: center; }
.brand-mark {
  width: 52px; height: 52px; border-radius: 10px;
  background: linear-gradient(150deg, #f4c95d, #9a7420);
  color: #191104; font-weight: 800; font-size: 22px;
  display: flex; align-items: center; justify-content: center;
  box-shadow: 0 0 26px #e0a83c44;
}
h1 { font-size: 24px; margin: 0; letter-spacing: .2px; }
h1 span { color: var(--brass); font-weight: 600; }
.sub { margin: 2px 0 0; color: var(--dim); font-size: 13px; }
.badges { display: flex; gap: 8px; flex-wrap: wrap; }
.badge {
  font-size: 12px; color: var(--dim); border: 1px solid var(--line);
  padding: 4px 10px; border-radius: 20px; background: var(--panel);
  font-family: var(--mono);
}
.badge.ok { color: var(--green); border-color: #1d4a34; }
.layout {
  display: grid; grid-template-columns: 430px 1fr; gap: 18px;
  max-width: 1180px; margin: 0 auto; padding: 6px 30px 20px;
}
@media (max-width: 980px) { .layout { grid-template-columns: 1fr; } }
.card {
  background: linear-gradient(180deg, var(--panel2), var(--panel));
  border: 1px solid var(--line); border-radius: 16px;
  padding: 18px; box-shadow: 0 18px 50px #0009;
}
.card-title { font-weight: 700; letter-spacing: .4px; margin-bottom: 12px; display: flex; justify-content: space-between; align-items: center; gap: 10px; flex-wrap: wrap; }
.card-title.small { font-size: 12px; color: var(--dim); text-transform: uppercase; letter-spacing: 1.2px; }
.seg { display: inline-flex; border: 1px solid var(--line); border-radius: 10px; overflow: hidden; }
.seg-btn { background: transparent; border: 0; color: var(--dim); font-weight: 700; font-size: 12px; padding: 5px 12px; cursor: pointer; }
.seg-btn.active { background: #3a2f14; color: var(--brass-hi); }
.mono { font-family: var(--mono); }
.state { font-size: 11px; padding: 3px 10px; border-radius: 12px; text-transform: uppercase; letter-spacing: 1px; }
.state.paused { background: #2a3440; color: var(--dim); }
.state.running { background: #3a2f14; color: var(--brass-hi); box-shadow: 0 0 12px #e0a83c44; }
.state.fault { background: #4a1717; color: var(--red); }
.board-wrap { display: flex; justify-content: center; }
.board { width: 100%; max-width: 390px; }
.pcb { fill: #12241c; }
.pcb-edge { fill: none; stroke: #6b5320; stroke-width: 2; }
.silk { fill: #d8c690; font: 600 13px sans-serif; letter-spacing: 2px; }
.silk.tiny { font-size: 8.5px; letter-spacing: 1px; fill: #7a6f52; }
.silk.big { font-size: 22px; font-weight: 800; }
.usb { fill: #31424f; stroke: #5a7183; }
.usb-hole { fill: #0a0f14; }
.pins circle { fill: #c9a227; }
.btn { fill: #31424f; stroke: #5a7183; }
.mcu { fill: #10161d; stroke: #3b4c5d; }
.led { fill: #3a2b12; stroke: #6b5320; stroke-width: 1.5; transition: fill .12s; }
.led.on { fill: var(--brass); stroke: var(--brass-hi); }
.led.small.on { fill: #57c7ff; stroke: #bfe9ff; }
.glow { fill: url(#g); opacity: 0; transition: opacity .12s; }
.glow.on { opacity: .85; }
.stats { display: flex; gap: 18px; margin: 12px 2px 4px; flex-wrap: wrap; }
.stat label { display: block; font-size: 11px; color: var(--dim); text-transform: uppercase; letter-spacing: 1px; }
.stat span { font-family: var(--mono); font-size: 15px; }
.ok { color: var(--green); } .bad { color: var(--red); }
.gpio { margin-top: 14px; }
.gpio-grid { display: grid; grid-template-columns: repeat(16, 1fr); gap: 5px; }
.pin { aspect-ratio: 1; border-radius: 50%; background: #1a2530; border: 1px solid #243140; transition: all .12s; }
.pin.hi { background: var(--brass); border-color: var(--brass-hi); box-shadow: 0 0 8px #e0a83c88; }
.pin.chg { outline: 1px solid var(--brass); }
.tabs { display: flex; gap: 6px; margin-bottom: 14px; flex-wrap: wrap; }
.tab {
  flex: 1; padding: 9px; border-radius: 10px; border: 1px solid var(--line);
  background: transparent; color: var(--dim); font-weight: 700; cursor: pointer;
}
.tab.active { background: #3a2f14; color: var(--brass-hi); border-color: var(--brass-dim); }
.tab:disabled { opacity: .38; cursor: not-allowed; }
.tabpane { display: none; }
.tabpane.active { display: block; }
.desc { color: var(--dim); font-size: 13.5px; margin: 0 0 12px; }
.row { display: flex; gap: 10px; margin-bottom: 12px; flex-wrap: wrap; }
.btn-acc {
  background: linear-gradient(150deg, #f4c95d, #c1902e); border: 0; color: #191104;
  font-weight: 800; padding: 10px 18px; border-radius: 10px; cursor: pointer;
  white-space: nowrap;
}
.btn-acc:disabled { opacity: .4; cursor: default; }
.btn-ghost {
  background: transparent; border: 1px solid var(--line); color: var(--ink);
  padding: 10px 16px; border-radius: 10px; cursor: pointer;
  white-space: nowrap;
}
.slider { display: flex; align-items: center; gap: 10px; color: var(--dim); font-size: 13px; }
.slider input { accent-color: var(--brass); }
.term {
  background: #060a08; border: 1px solid var(--line); border-radius: 10px;
  font-family: var(--mono); font-size: 13px; min-height: 150px; max-height: 300px;
  overflow-y: auto; padding: 12px; white-space: pre-wrap; color: #cfe3c0;
}
.term.small { min-height: 90px; }
.term .sys { color: #5f7a6c; }
.term .okline { color: var(--green); font-weight: 700; }
.enum { list-style: none; margin: 0 0 12px; padding: 0; font-size: 13px; max-height: 210px; overflow-y: auto; }
.enum li { padding: 3px 0 3px 24px; position: relative; color: var(--dim); }
.enum li::before { content: "○"; position: absolute; left: 4px; color: var(--dim); }
.enum li.run { color: var(--ink); } .enum li.run::before { content: "◌"; color: var(--brass); }
.enum li.done { color: var(--green); } .enum li.done::before { content: "●"; color: var(--green); }
.matrix-grid { display: grid; grid-template-columns: repeat(12, 1fr); gap: 5px; max-width: 340px; margin: 0 0 12px; }
.matrix-grid .mx { aspect-ratio: 1; border-radius: 50%; background: #182633; transition: background 0.08s, box-shadow 0.08s; }
.matrix-grid .mx.hi { background: var(--brass); box-shadow: 0 0 8px var(--brass); }
.doctable-wrap { overflow-x: auto; margin: 0 0 12px; border: 1px solid var(--line); border-radius: 10px; }
.doctable { width: 100%; border-collapse: collapse; font-size: 13px; }
.doctable th, .doctable td { text-align: left; padding: 7px 10px; border-bottom: 1px solid var(--line); vertical-align: top; }
.doctable thead th { color: var(--dim); font-weight: 600; font-size: 12px; text-transform: uppercase; letter-spacing: 0.04em; background: var(--panel2); }
.doctable tbody tr:last-child td { border-bottom: none; }
.doctable td:nth-child(2), .doctable td:nth-child(3) { white-space: nowrap; }
.doctable .st-done { color: var(--green); font-weight: 700; }
.doctable .st-part { color: var(--brass); font-weight: 700; }
.doctable .st-no { color: var(--dim); font-weight: 700; }
.doctable td:nth-child(4) { color: var(--dim); }
.textin {
  flex: 1; background: #060a08; border: 1px solid var(--line); color: var(--ink);
  border-radius: 10px; padding: 10px 12px; font-family: var(--mono); font-size: 13px;
}
.textin:disabled { opacity: .45; }
.banner { margin-top: 12px; padding: 10px 14px; border-radius: 10px; font-size: 13px; }
.banner.hidden { display: none; }
.banner.err { background: #3a1414; border: 1px solid #7a2a2a; color: #ff9d9d; }
.banner.info { background: #1d2b1a; border: 1px solid #3d5a2e; color: #cfe3c0; }

/* ---------- paper pages (docs / about) ---------- */
.page { max-width: 860px; margin: 0 auto; padding: 26px 30px 60px; overflow-x: clip; }
.page table { display: block; overflow-x: auto; }
.page-head { border-bottom: 2px solid var(--brass-dim); padding-bottom: 14px; margin-bottom: 6px; }
.page-kicker {
  font-family: var(--mono); font-size: 12px; color: var(--brass);
  letter-spacing: .14em; margin: 0 0 8px;
}
.page-title {
  font-family: var(--serif); font-weight: 700; font-size: 34px; line-height: 1.15;
  margin: 0 0 8px; letter-spacing: 0;
}
.page-lede { color: var(--dim); font-size: 15.5px; max-width: 62ch; margin: 0 0 4px; }
.page-toc {
  border: 1px solid var(--line); border-radius: 12px; background: var(--panel);
  padding: 12px 18px; margin: 18px 0 8px; font-size: 13.5px; color: var(--dim);
}
.page-toc b { color: var(--ink); }
.page-toc a { color: var(--brass-hi); text-decoration: none; }
.page-toc a:hover { text-decoration: underline; }
.page h2 {
  font-family: var(--serif); font-size: 23px; margin: 30px 0 8px;
  padding-top: 14px; border-top: 1px solid var(--rule);
}
.page h3 { font-size: 16px; margin: 20px 0 6px; color: var(--brass-hi); }
.page p, .page li { max-width: 72ch; }
.page p { margin: 8px 0; color: #c3cec0; }
.page ul, .page ol { padding-left: 22px; color: #c3cec0; }
.page li { margin: 4px 0; }
.page code {
  font-family: var(--mono); font-size: 12.5px; background: #060a08;
  border: 1px solid var(--line); border-radius: 6px; padding: 1px 6px;
  color: var(--brass-hi); white-space: nowrap;
}
.page pre {
  background: #060a08; border: 1px solid var(--line); border-radius: 10px;
  padding: 12px 14px; overflow-x: auto; font-family: var(--mono); font-size: 12.5px;
  color: #cfe3c0;
}
.page pre code { border: 0; background: none; padding: 0; white-space: pre; }
.page table { width: 100%; border-collapse: collapse; font-size: 13.5px; margin: 10px 0 18px; }
.page th, .page td { text-align: left; padding: 7px 10px; border-bottom: 1px solid var(--line); vertical-align: top; }
.page thead th { color: var(--dim); font-size: 12px; text-transform: uppercase; letter-spacing: .05em; }
.page .st-done { color: var(--green); font-weight: 700; }
.page .st-part { color: var(--brass); font-weight: 700; }
.page .st-no { color: var(--dim); font-weight: 700; }
.page a { color: var(--brass-hi); }
.foot-nav {
  max-width: 860px; margin: 0 auto; padding: 0 30px 40px;
  display: flex; gap: 12px; flex-wrap: wrap;
}
footer { max-width: 1180px; margin: 0 auto; padding: 0 30px 26px; color: var(--dim); font-size: 12.5px; }

/* ---------- accessibility floor ---------- */
:focus-visible { outline: 2px solid var(--brass-hi); outline-offset: 2px; }
.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}
.skip-link {
  position: absolute; left: 12px; top: -48px; z-index: 100;
  background: var(--brass); color: #191104; font-weight: 800;
  padding: 10px 16px; border-radius: 10px; text-decoration: none;
  transition: top .15s;
}
.skip-link:focus { top: 12px; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition: none !important; animation: none !important; }
}