* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  font-family: sans-serif;
  background: #f3f5f7;
  color: #222;
}

.timer-app {
  width: 520px;
  padding: 32px;
  border-radius: 16px;
  background: #ffffff;
  box-shadow: 0 12px 30px rgba(0, 0, 0, 0.12);
  text-align: center;
}

.timer-app h1 {
  margin-top: 0;
}

.time-inputs {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-bottom: 16px;
}

.time-inputs label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: bold;
}

.time-inputs input {
  width: 90px;
  padding: 10px;
  border: 1px solid #999;
  border-radius: 8px;
  font-size: 1.2rem;
  text-align: right;
}

.error-message {
  min-height: 1.5em;
  margin: 0 0 8px;
  color: #c62828;
  font-weight: bold;
}

.timer-display {
  margin: 16px 0 24px;
  font-size: 5rem;
  font-weight: bold;
  line-height: 1;
  letter-spacing: 0.05em;
}

.buttons {
  display: flex;
  justify-content: center;
  gap: 12px;
}

.buttons button {
  min-width: 120px;
  padding: 12px 18px;
  border: 0;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: bold;
  cursor: pointer;
}

#start-button {
  background: #2e7d32;
  color: #ffffff;
}

#pause-button {
  background: #f9a825;
  color: #222222;
}

#reset-button {
  background: #546e7a;
  color: #ffffff;
}

.buttons button:disabled {
  cursor: not-allowed;
  opacity: 0.45;
}