:root {
  --bg: #f6f7f9;
  --panel: #ffffff;
  --fg: #14161a;
  --muted: #6b7280;
  --line: #e4e7ec;
  --accent: #2563eb;
  --accent-fg: #ffffff;
  --stop: #dc2626;
  --fast: #16a34a;
  --slow: #dc2626;
  --shadow: 0 1px 2px rgba(16, 24, 40, .05), 0 12px 32px rgba(16, 24, 40, .08);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d0f13;
    --panel: #151920;
    --fg: #eceef2;
    --muted: #9aa3b2;
    --line: #262c36;
    --accent: #3b82f6;
    --accent-fg: #ffffff;
    --stop: #ef4444;
    --fast: #4ade80;
    --slow: #f87171;
    --shadow: 0 1px 2px rgba(0, 0, 0, .4), 0 12px 32px rgba(0, 0, 0, .45);
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100dvh;
  display: grid;
  place-items: center;
  padding: 24px;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Noto Sans JP", "Segoe UI", sans-serif;
  -webkit-font-smoothing: antialiased;
}

.app {
  width: 100%;
  max-width: 420px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 20px;
  box-shadow: var(--shadow);
  padding: 28px 24px 20px;
}

.title {
  margin: 0 0 18px;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--muted);
  text-align: center;
}

.display {
  font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, monospace;
  font-variant-numeric: tabular-nums;
  font-size: clamp(44px, 14vw, 60px);
  font-weight: 600;
  line-height: 1.1;
  text-align: center;
  letter-spacing: -.02em;
  margin-bottom: 24px;
}

.display .cs { color: var(--muted); }

.controls {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

.btn {
  appearance: none;
  border: 1px solid transparent;
  border-radius: 12px;
  padding: 13px 16px;
  font: inherit;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: background-color .12s ease, opacity .12s ease, transform .04s ease;
}

.btn:active:not(:disabled) { transform: scale(.98); }

.btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.btn-primary {
  background: var(--accent);
  color: var(--accent-fg);
}

.btn-primary.running { background: var(--stop); }

.btn-ghost {
  background: transparent;
  border-color: var(--line);
  color: var(--fg);
}

.btn-ghost:hover:not(:disabled) { background: var(--bg); }

.btn:disabled {
  opacity: .4;
  cursor: default;
}

.laps {
  list-style: none;
  margin: 20px 0 0;
  padding: 0;
  max-height: 220px;
  overflow-y: auto;
  font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, monospace;
  font-variant-numeric: tabular-nums;
  font-size: 14px;
}

.laps:empty { margin: 0; }

.laps li {
  display: grid;
  grid-template-columns: 3.2em 1fr auto;
  gap: 8px;
  align-items: baseline;
  padding: 9px 4px;
  border-top: 1px solid var(--line);
}

.laps li .no { color: var(--muted); font-size: 12px; }
.laps li .split { font-weight: 600; }
.laps li .total { color: var(--muted); font-size: 12px; text-align: right; }

.laps li.fast .split { color: var(--fast); }
.laps li.slow .split { color: var(--slow); }

.hint {
  margin: 18px 0 0;
  text-align: center;
  font-size: 12px;
  color: var(--muted);
}

kbd {
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 11px;
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: 5px;
  padding: 2px 5px;
}

@media (hover: none) {
  .hint { display: none; }
}