/* Mobile-first per SPEC §4: 500px max width, 44x44 min touch targets. */

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  line-height: 1.4;
}

.app {
  max-width: 500px;
  margin: 0 auto;
  padding: 0 1rem;
}

.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.5rem 0;
  border-bottom: 1px solid currentColor;
}

.tabs { display: flex; gap: 0.5rem; }

.tab {
  min-height: 44px;
  padding: 0 1rem;
  border: none;
  background: transparent;
  color: inherit;
  font: inherit;
  cursor: pointer;
}

.tab--active { font-weight: 600; text-decoration: underline; }

.running-timer { padding: 1rem 0; }

.btn {
  min-height: 44px;
  min-width: 44px;
  padding: 0 1.25rem;
  border: 1px solid currentColor;
  border-radius: 4px;
  background: transparent;
  color: inherit;
  font: inherit;
  cursor: pointer;
}

.timer__elapsed {
  font-size: 2.5rem;
  font-variant-numeric: tabular-nums;
  margin: 0.5rem 0;
}