:root {
  --ink: #1e2529;
  --muted: #5d676c;
  --rule: #c9cfd1;
  --paper: #ffffff;
  --ground: #eef0ee;
  --accent: #1557d0;
  --stop: #c4271f;
  --sans: 'IBM Plex Sans', system-ui, sans-serif;
  --mono: 'IBM Plex Mono', ui-monospace, monospace;
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--ground); color: var(--ink); font: 16px/1.35 var(--sans); }
a { color: var(--accent); }
button { font: 600 13px var(--sans); color: var(--ink); background: var(--paper); border: 1px solid var(--rule); border-radius: 4px; padding: 6px 10px; cursor: pointer; }
button:hover { border-color: var(--ink); }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

header { padding: 18px 24px 14px; background: var(--ink); color: #fff; }
.kicker { margin: 0; font: 500 12px var(--mono); letter-spacing: .08em; text-transform: uppercase; color: #aab4b8; }
h1 { margin: 2px 0 0; font-size: 28px; font-weight: 700; letter-spacing: -.01em; }
.emergency { margin: 0; padding: 10px 24px; background: #fff; border-bottom: 3px solid var(--stop); font-size: 15px; }
.emergency b { color: var(--stop); }
.ph { border-bottom: 2px dashed currentColor; padding: 0 2px; background: #fff7d6; }

main { display: grid; grid-template-columns: minmax(320px, 420px) minmax(0, 1fr); gap: 20px; max-width: 1400px; margin: 0 auto; padding: 20px 24px 32px; align-items: start; }

.steps { list-style: none; margin: 0; padding: 0; background: var(--paper); border: 1px solid var(--rule); border-radius: 6px; }
.step + .step { border-top: 1px solid var(--rule); }
.step button { all: unset; box-sizing: border-box; display: grid; grid-template-columns: 34px 1fr; gap: 12px; width: 100%; padding: 12px 14px; cursor: pointer; border-left: 4px solid transparent; }
.step button:focus-visible { outline: 2px solid var(--accent); outline-offset: -2px; }
.step.active button { border-left-color: var(--accent); background: #f2f6fd; }
.n { display: grid; place-items: center; width: 30px; height: 30px; border-radius: 50%; border: 2px solid var(--ink); font: 500 14px var(--mono); }
.active .n { background: var(--accent); border-color: var(--accent); color: #fff; }
.stop .n { border-color: var(--stop); color: var(--stop); }
.stop.active .n { background: var(--stop); color: #fff; }
.stop.active button { border-left-color: var(--stop); background: #fdf3f2; }
.body { display: grid; gap: 4px; padding-top: 4px; }
.title { font-size: 18px; font-weight: 700; line-height: 1.25; }
.stop .title { color: var(--stop); }
.line { display: flex; align-items: baseline; gap: 8px; font-size: 15px; line-height: 1.4; color: var(--muted); }
.line.warn { color: var(--stop); margin-top: 2px; }
.led { flex: none; width: 12px; height: 12px; border-radius: 50%; border: 1.5px solid var(--ink); transform: translateY(1px); }
.led.on { background: #e8336d; box-shadow: 0 0 0 3px rgba(232, 51, 109, .25); }
.led.off { background: #565b5e; }
.foot { font-size: 12px; color: var(--muted); margin: 10px 2px 0; }

.figure-col { display: grid; gap: 16px; position: sticky; top: 12px; }
.sheet { margin: 0; background: var(--paper); border: 1px solid var(--rule); border-radius: 6px; overflow: hidden; }
.sheet figcaption, .model-bar { display: flex; align-items: baseline; gap: 10px; flex-wrap: wrap; padding: 10px 14px; border-bottom: 1px solid var(--rule); }
.sheet figcaption b, .model-bar b { font-size: 15px; }
.sheet figcaption span { font-size: 13px; color: var(--muted); }
.drawing { padding: 16px; display: grid; place-items: center; }
.drawing svg { width: 100%; height: auto; max-height: 34vh; }
.sheet-foot { display: flex; justify-content: space-between; gap: 10px; margin: 0; padding: 6px 14px; border-top: 1px solid var(--rule); font: 500 11px var(--mono); color: var(--muted); text-transform: uppercase; letter-spacing: .04em; }
.model-bar { align-items: center; }
.spacer { flex: 1; }
.model { position: relative; height: 36vh; min-height: 260px; touch-action: none; }
.model canvas { display: block; }
.tags { position: absolute; inset: 0; pointer-events: none; overflow: hidden; }
.tags span { position: absolute; left: 0; top: 0; padding: 2px 6px; background: rgba(255,255,255,.92); border: 1px solid var(--ink); border-radius: 3px; font: 500 11px var(--mono); }

@media (max-width: 900px) {
  header { padding: 14px 16px 12px; }
  .emergency { padding: 10px 16px; }
  main { display: flex; flex-direction: column; padding: 12px 16px 24px; gap: 14px; }
  .figure-col { display: contents; }
  .sheet:not(.model-sheet) { order: 0; position: sticky; top: 0; z-index: 2; box-shadow: 0 6px 12px -8px rgba(0,0,0,.3); }
  .drawing { padding: 8px; }
  .drawing svg { max-height: 30vh; }
  .sheet-foot { display: none; }
  .steps-col { order: 1; }
  .model-sheet { order: 2; }
  .model-sheet .sheet-foot { display: flex; }
}

/* Drawing highlight: solid ring, pulsing halo, veil over everything else. */
.drawing .halo { animation: halo 1.8s ease-out infinite; }
@keyframes halo {
  0% { stroke-width: 3; opacity: .7; }
  100% { stroke-width: 22; opacity: 0; }
}
@media (prefers-reduced-motion: reduce) {
  .drawing .halo { animation: none; stroke-width: 10; opacity: .25; }
}