:root {
  --bg: #08090b;
  --panel: #12151a;
  --panel-2: #1a1e25;
  --line: #2a2f36;
  --text: #eef1f4;
  --muted: #8a929c;
  --accent: #ff7a1a;
  --accent-2: #ffb347;
  --red: #ff3b3b;
  --rev: 0; /* 0..1, set from JS */
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; }
body {
  background: var(--bg);
  color: var(--text);
  display: grid;
  grid-template-rows: auto 1fr auto;
  overflow: hidden;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
}

/* Background: fine diagonal weave + glow that grows with the revs */
.backdrop {
  position: fixed; inset: 0; z-index: -1;
  background:
    radial-gradient(ellipse at 50% 45%, transparent 0 30%, var(--bg) 75%),
    repeating-linear-gradient(45deg, #0e1014 0 3px, #0b0c0f 3px 6px),
    repeating-linear-gradient(-45deg, #0e1014 0 3px, #0b0c0f 3px 6px);
  background-blend-mode: normal, lighten, normal;
}
.backdrop-glow {
  position: absolute; left: 0; right: 0; bottom: 0; height: 45%;
  background: radial-gradient(ellipse at 50% 100%, rgba(255, 122, 26, .35), transparent 70%);
  opacity: calc(.15 + var(--rev) * .85);
  transition: opacity .1s linear;
}

/* Top bar */
.topbar {
  display: flex; align-items: center; justify-content: space-between;
  padding: max(12px, env(safe-area-inset-top)) 20px 12px;
}
.brand { display: flex; align-items: center; gap: 10px; letter-spacing: .18em; font-weight: 600; font-size: 14px; }
.brand b { color: var(--accent); font-weight: 800; }
.icon-btn {
  width: 48px; height: 48px; border-radius: 12px; border: 1px solid var(--line);
  background: var(--panel); color: var(--text); cursor: pointer; display: grid; place-items: center;
}
.icon-btn svg { width: 24px; height: 24px; }

/* Cluster */
.cluster { display: grid; place-items: center; align-content: center; gap: 8px; min-height: 0; }
.gauge {
  position: relative;
  width: min(72vh, 92vw, 640px);
  aspect-ratio: 1;
}
.gauge canvas { width: 100%; height: 100%; display: block; }
.readout {
  position: absolute; inset: 0; display: grid; place-content: center; text-align: center; gap: 2px;
  pointer-events: none;
}
.gear {
  font-size: clamp(28px, 7vh, 56px); font-weight: 800; color: var(--accent);
  font-variant-numeric: tabular-nums;
}
.speed span { font-size: clamp(56px, 15vh, 128px); font-weight: 700; line-height: .95; font-variant-numeric: tabular-nums; }
.speed small { display: block; color: var(--muted); font-size: 14px; letter-spacing: .2em; text-transform: uppercase; }
.rpm-text { color: var(--muted); font-size: 13px; font-variant-numeric: tabular-nums; margin-top: 6px; }
.status { min-height: 1.4em; color: var(--muted); font-size: 14px; text-align: center; padding: 0 16px; }

body.is-off .gauge { opacity: .35; filter: saturate(.4); transition: opacity .4s, filter .4s; }

/* Start panel */
.start {
  display: grid; justify-items: center; gap: 14px;
  padding: 0 16px max(20px, env(safe-area-inset-bottom));
}
body.is-on .start { display: none; }
.engine-grid {
  display: grid; gap: 10px; width: min(100%, 980px);
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
}
.engine {
  text-align: left; padding: 12px 14px; border-radius: 14px; cursor: pointer;
  background: var(--panel); border: 1px solid var(--line); color: var(--text);
  display: grid; gap: 4px; min-height: 64px;
}
.engine .name { font-weight: 700; font-size: 15px; }
.engine .spec { color: var(--muted); font-size: 12px; }
.engine[aria-checked="true"] { border-color: var(--accent); background: linear-gradient(180deg, #2a1a0e, var(--panel)); }
.engine[aria-checked="true"] .name { color: var(--accent-2); }

.start-btn {
  width: 140px; height: 140px; border-radius: 50%; cursor: pointer;
  font-size: 22px; font-weight: 800; letter-spacing: .15em; color: #fff;
  background: radial-gradient(circle at 50% 35%, #ff9a4a, var(--accent) 45%, #a33c00);
  border: 6px solid #1c1f25;
  box-shadow: 0 0 0 2px var(--accent), 0 10px 40px rgba(255, 122, 26, .35);
  transition: transform .1s;
}
.start-btn:active { transform: scale(.96); }
.hint { margin: 0; color: var(--muted); font-size: 13px; text-align: center; }

/* Dock */
.dock {
  display: flex; justify-content: center; gap: 14px; flex-wrap: wrap;
  padding: 0 16px max(20px, env(safe-area-inset-bottom));
}
.dock[hidden], .dock [hidden] { display: none; }
.gas-btn, .stop-btn {
  height: 72px; padding: 0 32px; border-radius: 18px; font-size: 18px; font-weight: 700; cursor: pointer;
  border: 1px solid var(--line); color: var(--text); background: var(--panel-2);
  touch-action: none;
}
.gas-btn { min-width: 240px; background: linear-gradient(180deg, #2c1a0c, #1a1209); border-color: var(--accent); }
.gas-btn.held { background: var(--accent); color: #111; }

/* Dialogs */
.sheet {
  width: min(520px, 94vw); border: 1px solid var(--line); border-radius: 18px;
  background: var(--panel); color: var(--text); padding: 22px;
}
.sheet::backdrop { background: rgba(0, 0, 0, .65); }
.sheet h2 { margin: 0 0 12px; font-size: 20px; }
.sheet p { line-height: 1.5; }
.fine { color: var(--muted); font-size: 13px; }
.row { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 16px; }
.btn {
  min-height: 48px; padding: 0 20px; border-radius: 12px; font-size: 15px; font-weight: 600; cursor: pointer;
  border: 1px solid var(--line); background: var(--panel-2); color: var(--text);
}
.btn.primary { background: var(--accent); border-color: var(--accent); color: #111; }

.field { display: grid; gap: 8px; margin: 0 0 16px; padding: 0; border: 0; }
.field legend { padding: 0; margin-bottom: 8px; }
.field input[type="range"] { width: 100%; accent-color: var(--accent); }
.toggle { grid-template-columns: auto 1fr; align-items: center; cursor: pointer; }
.toggle input { width: 22px; height: 22px; accent-color: var(--accent); }
.toggle small { color: var(--muted); }
.seg { display: inline-flex; border: 1px solid var(--line); border-radius: 12px; overflow: hidden; width: max-content; }
.seg input { position: absolute; opacity: 0; }
.seg span { display: block; padding: 12px 22px; cursor: pointer; }
.seg input:checked + span { background: var(--accent); color: #111; font-weight: 700; }
.seg input:focus-visible + span { outline: 2px solid #fff; outline-offset: -4px; }

button:focus-visible { outline: 2px solid #fff; outline-offset: 2px; }

@media (max-height: 640px) {
  .start-btn { width: 96px; height: 96px; font-size: 17px; }
  .engine { min-height: 52px; padding: 8px 12px; }
}
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; }
}