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

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: #f7f7f7;
  color: #111;
  min-height: 100vh;
}

.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 24px;
  text-align: center;
}

h1 {
  font-size: 2rem;
  margin-bottom: 8px;
}

.subtitle {
  color: #555;
  margin-bottom: 24px;
}

.timer-display {
  font-size: 4rem;
  font-weight: 600;
  margin: 24px 0;
  color: #2563eb;
}

.controls {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-bottom: 20px;
}

button {
  padding: 12px 18px;
  font-size: 1rem;
  border-radius: 10px;
  border: none;
  cursor: pointer;
  background: #2563eb;
  color: #fff;
}

button.secondary {
  background: #e5e7eb;
  color: #111;
}

.presets {
  display: flex;
  justify-content: center;
  gap: 10px;
  margin-bottom: 24px;
}

.presets button {
  background: #fff;
  color: #111;
  border: 1px solid #ddd;
}

footer {
  margin-top: 28px;
  font-size: 0.9rem;
  color: #666;
}

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

.custom-time input {
  width: 110px;
  padding: 10px;
  font-size: 1rem;
  border-radius: 10px;
  border: 1px solid #ddd;
}

.custom-time button {
  background: #16a34a;
}