:root {
  color-scheme: light dark;
  --bg: #f4f5f7;
  --card: #ffffff;
  --text: #1c1e21;
  --muted: #6b7280;
  --accent: #2563eb;
  --accent-text: #ffffff;
  --danger: #dc2626;
  --border: #e5e7eb;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14161a;
    --card: #1f2229;
    --text: #f2f3f5;
    --muted: #9aa0aa;
    --accent: #3b82f6;
    --accent-text: #ffffff;
    --danger: #f87171;
    --border: #2c303a;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "Noto Sans JP", sans-serif;
  padding: 24px;
}

.card {
  width: 100%;
  max-width: 420px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 32px 28px;
  text-align: center;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
}

h1 {
  margin: 0 0 24px;
  font-size: 1.3rem;
}

.display {
  font-variant-numeric: tabular-nums;
  font-size: 3rem;
  font-weight: 700;
  letter-spacing: 1px;
  margin-bottom: 28px;
}

.controls {
  display: flex;
  gap: 10px;
  justify-content: center;
  margin-bottom: 20px;
}

button {
  appearance: none;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
  padding: 10px 20px;
  border-radius: 999px;
  font-size: 0.95rem;
  cursor: pointer;
  transition: opacity 0.15s ease, transform 0.05s ease;
}

button:active { transform: scale(0.97); }

button:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

button.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-text);
}

button.primary.running {
  background: var(--danger);
  border-color: var(--danger);
}

.laps {
  list-style: none;
  margin: 0;
  padding: 0;
  max-height: 220px;
  overflow-y: auto;
  text-align: left;
  border-top: 1px solid var(--border);
}

.laps li {
  display: flex;
  justify-content: space-between;
  padding: 8px 4px;
  border-bottom: 1px solid var(--border);
  font-variant-numeric: tabular-nums;
  color: var(--muted);
  font-size: 0.9rem;
}

.laps li:first-child {
  color: var(--text);
  font-weight: 600;
}