:root {
  --bg: #07070d;
  --surface: #0f0f1a;
  --surface2: #161625;
  --border: rgba(255,255,255,0.07);
  --border2: rgba(255,255,255,0.13);
  --text: #dde1f0;
  --muted: #5c6080;
  --accent: #5b6ef5;
  --accent-light: #8b98ff;
  --accent-bg: rgba(91,110,245,0.12);
  --accent-border: rgba(91,110,245,0.35);
  --warn: #f0a040;
  --warn-bg: rgba(240,160,64,0.1);
  --warn-border: rgba(240,160,64,0.3);
  --mono: 'IBM Plex Mono', monospace;
  --sans: 'IBM Plex Sans', sans-serif;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-weight: 300;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
}

/* ── Intro ── */

#intro {
  width: 100%;
  max-width: 680px;
  padding: 56px 24px 0;
}

.wordmark {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: .18em;
  color: var(--muted);
  text-transform: uppercase;
  margin-bottom: 28px;
  display: flex;
  align-items: center;
  gap: 10px;
}
.wordmark::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border);
}

.lang-switch {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: .06em;
  color: var(--accent-light);
  text-decoration: none;
  border: 1px solid var(--accent-border);
  border-radius: 4px;
  padding: 2px 8px;
  transition: background .12s, color .12s;
  flex-shrink: 0;
}
.lang-switch:hover {
  background: var(--accent-bg);
  color: #fff;
}

h1 {
  font-family: var(--mono);
  font-size: clamp(22px, 4vw, 32px);
  font-weight: 500;
  letter-spacing: -.02em;
  line-height: 1.2;
  margin-bottom: 16px;
  color: #fff;
}
h1 span { color: var(--accent-light); }

.tagline {
  font-size: 15px;
  line-height: 1.75;
  color: var(--muted);
  max-width: 520px;
  margin-bottom: 32px;
}

.rules-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-bottom: 40px;
}
.rule {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px 16px;
}
.rule-num {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: .12em;
  color: var(--accent-light);
  margin-bottom: 6px;
}
.rule-text {
  font-size: 13px;
  line-height: 1.55;
  color: var(--text);
}

.divider {
  width: 100%;
  height: 1px;
  background: var(--border);
  margin-bottom: 36px;
}

/* ── Demo ── */

#demo {
  width: 100%;
  max-width: 680px;
  padding: 0 24px;
}

/* Status bar */

#status {
  display: flex;
  align-items: stretch;
  gap: 10px;
  margin-bottom: 20px;
  min-height: 48px;
}

.status-locks {
  flex: 1;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 14px;
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
}

.lock-tag {
  font-family: var(--mono);
  font-size: 11px;
  background: var(--accent-bg);
  border: 1px solid var(--accent-border);
  border-radius: 4px;
  padding: 2px 8px;
  color: var(--accent-light);
  letter-spacing: .04em;
  animation: tagIn .15s ease;
}
@keyframes tagIn { from { opacity: 0; transform: scale(.9); } }

.status-hint {
  font-size: 12px;
  color: var(--muted);
  font-style: italic;
}

.status-pool {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 16px;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  justify-content: center;
  min-width: 100px;
}

.pool-num {
  font-family: var(--mono);
  font-size: 22px;
  font-weight: 500;
  color: #fff;
  line-height: 1;
}

.pool-label {
  font-size: 10px;
  letter-spacing: .08em;
  color: var(--muted);
  margin-top: 2px;
}

/* FIFO toast */

#fifo-toast {
  background: var(--warn-bg);
  border: 1px solid var(--warn-border);
  border-radius: 8px;
  padding: 10px 14px;
  font-size: 12px;
  font-family: var(--mono);
  color: var(--warn);
  margin-bottom: 14px;
  opacity: 0;
  transition: opacity .3s;
  pointer-events: none;
}
#fifo-toast.show { opacity: 1; }

/* Navigator grid */

#navigator {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
  margin-bottom: 20px;
}

.dir-btn {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  aspect-ratio: 1;
  transition: background .12s, border-color .12s, transform .08s;
  -webkit-tap-highlight-color: transparent;
  position: relative;
  overflow: hidden;
}
.dir-btn::before {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--accent-bg);
  opacity: 0;
  transition: opacity .12s;
}
.dir-btn:hover { border-color: var(--border2); }
.dir-btn:hover::before { opacity: 1; }
.dir-btn:active { transform: scale(.95); }
.dir-btn.locked {
  background: var(--accent-bg);
  border-color: var(--accent-border);
}
.dir-btn.unlocked-flash { animation: unlockFlash .5s ease; }
@keyframes unlockFlash {
  0%, 100% {}
  40% { background: var(--warn-bg); border-color: var(--warn-border); }
}

.dir-arrow {
  font-size: 13px;
  color: var(--muted);
  line-height: 1;
}
.dir-btn.locked .dir-arrow { color: var(--accent-light); }

.dir-val {
  font-family: var(--mono);
  font-size: 28px;
  font-weight: 500;
  color: var(--text);
  line-height: 1;
  position: relative;
}
.dir-btn.locked .dir-val { color: #fff; }

/* Current card */

#current-card {
  background: var(--surface2);
  border: 2px solid var(--accent-border);
  border-radius: 12px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 6px;
  aspect-ratio: 1;
  position: relative;
}

.card-id {
  font-family: var(--mono);
  font-size: 36px;
  font-weight: 500;
  color: #fff;
  line-height: 1;
}

.card-sub {
  font-size: 10px;
  font-family: var(--mono);
  color: var(--muted);
  letter-spacing: .06em;
}

.cycle-indicator {
  position: absolute;
  bottom: 10px;
  display: flex;
  gap: 4px;
}

.cycle-dot {
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--border2);
  transition: background .2s;
}
.cycle-dot.active { background: var(--accent-light); }

/* Loop pool */

#pool-display {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 16px;
  margin-bottom: 16px;
}

.pool-title {
  font-size: 10px;
  letter-spacing: .1em;
  color: var(--muted);
  text-transform: uppercase;
  margin-bottom: 10px;
  font-family: var(--mono);
}

.pool-cards {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.pool-card {
  font-family: var(--mono);
  font-size: 12px;
  padding: 3px 9px;
  border-radius: 4px;
  border: 1px solid var(--border);
  color: var(--muted);
  transition: all .15s;
}
.pool-card.visited {
  border-color: rgba(139,152,255,0.25);
  color: var(--accent-light);
  opacity: .7;
}
.pool-card.current {
  background: var(--accent-bg);
  border-color: var(--accent-border);
  color: var(--accent-light);
  opacity: 1;
}

.pool-empty {
  font-size: 12px;
  color: var(--muted);
  font-style: italic;
}

/* History */

#history-row {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
  margin-bottom: 32px;
  min-height: 28px;
  padding: 8px 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
}

.hist-label {
  font-size: 10px;
  letter-spacing: .1em;
  color: var(--muted);
  font-family: var(--mono);
  text-transform: uppercase;
  margin-right: 2px;
}

.hist-item {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--muted);
  padding: 1px 7px;
  border-radius: 3px;
  border: 1px solid var(--border);
}
.hist-item.current {
  color: var(--text);
  border-color: var(--border2);
}

.hist-sep { color: var(--border2); font-size: 12px; }
.hist-empty {
  font-size: 12px;
  color: var(--muted);
  font-style: italic;
}

/* Controls */

#controls {
  display: flex;
  gap: 8px;
  margin-bottom: 48px;
}

.ctrl-btn {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: .06em;
  padding: 8px 16px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--muted);
  cursor: pointer;
  transition: all .12s;
}
.ctrl-btn:hover {
  border-color: var(--border2);
  color: var(--text);
}
.ctrl-btn:disabled {
  opacity: .35;
  cursor: default;
}

.ctrl-toggle {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: .06em;
  padding: 8px 16px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: all .12s;
}
.ctrl-toggle:hover {
  border-color: var(--border2);
  color: var(--text);
}
.ctrl-toggle input {
  accent-color: var(--accent);
}

/* Footer */

#footer {
  width: 100%;
  max-width: 680px;
  padding: 20px 24px 48px;
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer-text {
  font-size: 11px;
  font-family: var(--mono);
  color: var(--muted);
  letter-spacing: .05em;
}

.footer-link {
  font-size: 11px;
  font-family: var(--mono);
  color: var(--accent-light);
  text-decoration: none;
  letter-spacing: .05em;
  opacity: .7;
  transition: opacity .15s;
}
.footer-link:hover { opacity: 1; }

/* ── Responsive ── */

@media (max-width: 480px) {
  .rules-grid { grid-template-columns: 1fr; }
  .dir-val { font-size: 22px; }
  .card-id { font-size: 28px; }
}