body {
  margin: 0;
  font-family: system-ui, sans-serif;
  background: #111;
  color: #fff;
}

header {
  text-align: center;
  padding: 0.5rem;
  background: #222;
}

.screen {
  display: none;
  padding: 1rem;
}

.screen.active {
  display: block;
}

.reps-container,
.timers-container {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  justify-content: center;
  margin-bottom: 1rem;
}

.rep-btn,
.timer-btn {
  padding: 0.75rem 1rem;
  border: none;
  border-radius: 6px;
  font-size: 1rem;
  cursor: pointer;
}

.rep-btn {
  background: #00aa00;
  color: #fff;
}

.rep-btn.active {
  background: #ffcc00;
  color: #000;
}

.timer-btn {
  background: #00aa00;
  color: #fff;
}

#timer-display {
  font-size: 3rem;
  text-align: center;
  margin: 2rem 0;
}

#stop-btn {
  display: block;
  margin: 0 auto;
  padding: 1rem 2rem;
  font-size: 1.2rem;
  border-radius: 8px;
  border: none;
  background: #ff0000;
  color: #fff;
  cursor: pointer;
}

section#screen-settings label {
  display: block;
  margin: 0.5rem 0;
}

.settings-actions {
  margin-top: 1rem;
  display: flex;
  gap: 0.5rem;
  justify-content: center;
}

button {
  touch-action: manipulation;
}

@media (min-width: 600px) {
  #timer-display {
    font-size: 4rem;
  }
}