:root {
  --bg: #0d1117;
  --panel: #161b22;
  --panel-2: #1f2631;
  --border: #30363d;
  --text: #e6edf3;
  --muted: #8b949e;
  --accent: #f97316;
  --accent-strong: #fb923c;
  --beat: #30363d;
  --beat-active: #f97316;
  --beat-accent: #fbbf24;
  --shadow: 0 6px 20px rgba(0, 0, 0, 0.4);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: radial-gradient(circle at 50% 0%, #1a2230 0%, var(--bg) 60%);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "Yu Gothic UI", sans-serif;
  min-height: 100vh;
}

main {
  max-width: 640px;
  margin: 0 auto;
  padding: 2rem 1.25rem 4rem;
}

header h1 {
  font-size: 1.75rem;
  margin: 0 0 0.25rem;
  letter-spacing: -0.01em;
}
.tagline {
  margin: 0 0 2rem;
  color: var(--muted);
  font-size: 0.95rem;
}
.tagline code {
  background: var(--panel-2);
  padding: 1px 6px;
  border-radius: 4px;
  font-size: 0.85em;
}

.display {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  box-shadow: var(--shadow);
  margin-bottom: 1.5rem;
}

.beats {
  display: flex;
  gap: 0.5rem;
  justify-content: center;
  margin-bottom: 1.5rem;
  min-height: 24px;
  flex-wrap: wrap;
}

.beat {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--beat);
  transition: background 70ms ease-out, transform 70ms ease-out;
}
.beat.on { background: var(--beat-active); transform: scale(1.25); }
.beat.on.accent { background: var(--beat-accent); }

.tempo {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  margin-bottom: 0.75rem;
}

.bpm {
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
}

#bpm {
  background: transparent;
  border: none;
  color: var(--text);
  font-size: 3.5rem;
  font-weight: 200;
  width: 4.5ch;
  text-align: center;
  font-variant-numeric: tabular-nums;
  -moz-appearance: textfield;
}
#bpm::-webkit-outer-spin-button,
#bpm::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
#bpm:focus { outline: none; }

.bpm-label {
  color: var(--muted);
  font-size: 0.85rem;
  letter-spacing: 0.1em;
}

.bpm-btn {
  background: var(--panel-2);
  border: 1px solid var(--border);
  color: var(--text);
  width: 40px;
  height: 40px;
  border-radius: 50%;
  font-size: 1.25rem;
  cursor: pointer;
  transition: background 120ms, border-color 120ms;
}
.bpm-btn:hover { background: var(--border); border-color: var(--muted); }

#bpmSlider {
  width: 100%;
  accent-color: var(--accent);
}

.controls {
  display: flex;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.controls button {
  flex: 1;
  padding: 0.9rem;
  border-radius: 10px;
  border: 1px solid var(--border);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 120ms, border-color 120ms, color 120ms;
}

.play {
  background: var(--accent);
  color: #0d1117;
  border-color: var(--accent);
}
.play:hover { background: var(--accent-strong); }
.play.playing { background: var(--panel-2); color: var(--text); border-color: var(--border); }

.tap {
  background: var(--panel-2);
  color: var(--text);
}
.tap:hover { background: var(--border); }
.tap:active { transform: translateY(1px); }

.signature, .presets, .shortcuts {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem 1.25rem;
  margin-bottom: 1rem;
}

.signature {
  display: flex;
  gap: 1rem;
  align-items: center;
  flex-wrap: wrap;
}
.signature label { color: var(--muted); font-size: 0.9rem; display: flex; align-items: center; gap: 0.4rem; }
.signature select {
  background: var(--panel-2);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.35rem 0.6rem;
  font-size: 0.95rem;
}

.presets h2, .shortcuts h2 {
  margin: 0 0 0.75rem;
  font-size: 0.85rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
}

.preset-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
  gap: 0.5rem;
}
.preset {
  background: var(--panel-2);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 0.55rem 0.6rem;
  border-radius: 8px;
  font-size: 0.85rem;
  cursor: pointer;
  transition: background 120ms, border-color 120ms;
}
.preset:hover { background: var(--border); border-color: var(--muted); }
.preset.active { border-color: var(--accent); color: var(--accent-strong); }

.shortcuts dl {
  margin: 0;
  display: grid;
  grid-template-columns: max-content 1fr;
  gap: 0.35rem 1rem;
  font-size: 0.9rem;
}
.shortcuts dt {
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 0.85rem;
  color: var(--accent-strong);
}
.shortcuts dd { margin: 0; color: var(--muted); }

footer {
  color: var(--muted);
  font-size: 0.85rem;
  text-align: center;
  padding: 2rem 0 0;
}
footer a { color: var(--accent-strong); }