:root {
  --bg: #0f1220;
  --card: #1a1e30;
  --card-2: #222741;
  --border: #2f3554;
  --text: #e8eaf6;
  --muted: #9aa0c3;
  --accent: #6c8cff;
  --accent-strong: #4a6cf7;
  --good: #3ddc97;
  --danger: #ff6b81;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: "Segoe UI", "Microsoft JhengHei", "Noto Sans TC", system-ui, sans-serif;
  background: radial-gradient(1200px 600px at 70% -10%, #232a4d 0%, var(--bg) 55%);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 24px 16px 40px;
}

header { text-align: center; margin-bottom: 20px; }
header h1 { font-size: 2rem; letter-spacing: 2px; }
.subtitle { color: var(--muted); margin-top: 6px; font-size: .95rem; }

main {
  width: 100%;
  max-width: 560px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 20px;
  box-shadow: 0 8px 24px rgba(0,0,0,.35);
}
.card h2 { font-size: 1.15rem; margin-bottom: 14px; color: #fff; }
.card h3 { font-size: 1rem; margin: 18px 0 10px; color: #dfe3ff; }

/* 節拍指示燈 */
.beat-dots { display: flex; gap: 12px; justify-content: center; margin: 6px 0 18px; }
.dot {
  width: 20px; height: 20px; border-radius: 50%;
  background: var(--card-2);
  border: 1px solid var(--border);
  transition: transform .08s ease, background .08s ease;
}
.dot.accent { border-color: var(--accent); }
.dot.on { background: var(--accent-strong); transform: scale(1.35); box-shadow: 0 0 14px var(--accent-strong); }
.dot.accent.on { background: #ffb347; box-shadow: 0 0 16px #ffb347; }

/* BPM */
.bpm-row { display: flex; align-items: center; justify-content: center; gap: 18px; }
.bpm-display { text-align: center; line-height: 1; }
.bpm-display span { font-size: 3.2rem; font-weight: 700; font-variant-numeric: tabular-nums; }
.bpm-display small { display: block; color: var(--muted); letter-spacing: 3px; margin-top: 4px; }

.ctrl {
  width: 46px; height: 46px; border-radius: 50%;
  background: var(--card-2); color: var(--text);
  border: 1px solid var(--border);
  font-size: 1.4rem; cursor: pointer;
}
.ctrl:hover { border-color: var(--accent); }
.ctrl:active { transform: scale(.94); }

input[type=range] { width: 100%; accent-color: var(--accent-strong); cursor: pointer; }
#bpmSlider { margin-top: 14px; }

.row { display: flex; gap: 16px; align-items: end; margin-top: 14px; flex-wrap: wrap; }
.field { display: flex; flex-direction: column; gap: 6px; font-size: .85rem; color: var(--muted); }
.field.grow { flex: 1; min-width: 140px; }
select {
  background: var(--card-2); color: var(--text);
  border: 1px solid var(--border); border-radius: 8px;
  padding: 8px 10px; font-size: 1rem;
}

.btn-row { display: flex; gap: 12px; margin-top: 18px; justify-content: center; flex-wrap: wrap; }
button {
  font-family: inherit; cursor: pointer;
  border-radius: 10px; border: 1px solid var(--border);
  background: var(--card-2); color: var(--text);
  padding: 10px 18px; font-size: .95rem;
  transition: filter .15s ease, transform .05s ease;
}
button:hover { filter: brightness(1.15); }
button:active { transform: scale(.97); }
.primary {
  background: linear-gradient(135deg, var(--accent-strong), var(--accent));
  border: none; color: #fff; font-weight: 600; padding: 12px 32px; font-size: 1.05rem;
  min-width: 130px;
}
.secondary { border-color: var(--accent); color: var(--accent); }
.danger { border-color: var(--danger); color: var(--danger); background: transparent; }
.danger-row { display: flex; justify-content: flex-end; margin-top: 16px; }

.hint { color: var(--muted); font-size: .85rem; margin-bottom: 14px; line-height: 1.5; }

/* 樂器選擇 */
.instruments { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 12px; }
.pill {
  position: relative;
  padding: 8px 14px; border-radius: 999px;
  background: var(--card-2); border: 1px solid var(--border);
  color: var(--text); font-size: .92rem; cursor: pointer;
}
.pill:hover { border-color: var(--accent); }
.pill.active { background: var(--accent-strong); border-color: var(--accent-strong); color: #fff; font-weight: 600; }
.pill .remove {
  margin-left: 8px; padding: 0 4px; font-size: .8rem;
  background: none; border: none; color: rgba(255,255,255,.65);
}
.pill .remove:hover { color: #fff; }

.add-instrument { display: flex; gap: 8px; margin-bottom: 18px; }
.add-instrument input {
  flex: 1; background: var(--card-2); border: 1px solid var(--border);
  border-radius: 8px; color: var(--text); padding: 9px 12px; font-size: .95rem;
}
.add-instrument input:focus { outline: none; border-color: var(--accent); }

/* 計時器 */
.timer-display {
  text-align: center; font-size: 3.6rem; font-weight: 700;
  font-variant-numeric: tabular-nums;
  margin: 10px 0 4px; color: var(--good);
  text-shadow: 0 0 24px rgba(61,220,151,.25);
}
.timer-display.running { animation: pulse 1s infinite alternate; }
@keyframes pulse { from { opacity: .85; } to { opacity: 1; } }

/* 統計 */
.stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; margin-top: 20px; }
.stat-box {
  background: var(--card-2); border: 1px solid var(--border);
  border-radius: 12px; padding: 12px 8px; text-align: center;
}
.stat-box .num { font-size: 1.25rem; font-weight: 700; color: #fff; font-variant-numeric: tabular-nums; }
.stat-box .lbl { font-size: .78rem; color: var(--muted); margin-top: 4px; }

/* 圖表 */
.chart { display: flex; flex-direction: column; gap: 8px; margin-top: 16px; }
.bar-row { display: grid; grid-template-columns: 76px 1fr 64px; align-items: center; gap: 10px; font-size: .85rem; }
.bar-track { height: 14px; background: var(--card-2); border-radius: 7px; overflow: hidden; border: 1px solid var(--border); }
.bar-fill { height: 100%; background: linear-gradient(90deg, var(--accent-strong), var(--accent)); border-radius: 7px; min-width: 2px; transition: width .4s ease; }
.bar-time { text-align: right; color: var(--muted); font-variant-numeric: tabular-nums; }

/* 紀錄列表 */
.sessions { list-style: none; display: flex; flex-direction: column; gap: 8px; }
.sessions li {
  display: flex; align-items: center; justify-content: space-between; gap: 10px;
  background: var(--card-2); border: 1px solid var(--border);
  border-radius: 10px; padding: 10px 14px; font-size: .88rem;
}
.session-info { display: flex; flex-direction: column; gap: 2px; min-width: 0; }
.session-inst { font-weight: 600; }
.session-date { color: var(--muted); font-size: .78rem; }
.session-dur { color: var(--good); font-weight: 700; white-space: nowrap; font-variant-numeric: tabular-nums; }
.del-btn { background: none; border: none; color: var(--muted); font-size: .8rem; padding: 4px 8px; }
.del-btn:hover { color: var(--danger); }
.empty { color: var(--muted); text-align: center; padding: 16px 0 !important; border-style: dashed !important; background: transparent !important; }

footer { margin-top: 28px; color: var(--muted); font-size: .78rem; }

@media (max-width: 480px) {
  .stats { grid-template-columns: repeat(3, 1fr); }
  .bar-row { grid-template-columns: 64px 1fr 56px; }
}