:root {
  --bg: #0b1020;
  --panel: #111631;
  --text: #e8ecf2;
  --muted: #97a0b3;
  --accent: #4f7cff;
  --danger: #ef4444;
  --border: #232b53;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: radial-gradient(1200px 900px at 20% -20%, #1a2260 0%, #0b1020 60%);
  color: var(--text);
  font: 16px/1.5 system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
}
.container {
  max-width: 900px;
  margin: 40px auto;
  padding: 24px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: 0 20px 60px rgba(0,0,0,0.35);
}
h1 { margin: 0; font-size: 24px; letter-spacing: 0.3px; }
.row { display: flex; align-items: center; gap: 12px; margin-bottom: 14px; }
.wrap { flex-wrap: wrap; }
.label { font-weight: 600; color: var(--text); display: inline-flex; gap: 8px; align-items: center; }
input[type=number] {
  width: 86px; padding: 8px 10px; border-radius: 10px; border: 1px solid var(--border);
  background: #0f1533; color: var(--text);
}
.btn {
  padding: 10px 16px;
  border-radius: 10px; border: 1px solid transparent;
  background: var(--accent); color: white; cursor: pointer;
}
.btn.stop { background: var(--danger); }
.subtle { color: var(--muted); font-size: 12px; }

.chip {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 6px 10px; border-radius: 999px;
  background: #0f1533; border: 1px solid var(--border);
  user-select: none; cursor: pointer;
}

#roots { display: flex; gap: 8px; flex-wrap: wrap; }
.root-toggle {
  padding: 6px 10px; border-radius: 999px; border: 1px solid var(--border);
  background: #0f1533; color: var(--text); cursor: pointer;
}
.root-toggle.active { background: var(--accent); border-color: var(--accent); color: white; }

.chord {
  font-size: 84px;
  font-weight: 900;
  letter-spacing: -1px;
  text-align: center;
  margin: 28px 0 4px;
}