body {
  font-family: 'Arial', sans-serif;
  background-color: #f4f4f4;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100vh;
  margin: 0;
}

.header {
  text-align: center;
  background-color: #4CAF50;
  color: white;
  padding: 20px;
  border-radius: 10px;
  margin-bottom: 20px;
  width: 90%;
  max-width: 500px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

.header h1 {
  margin: 0;
  font-size: 26px;
}

.header p {
  margin-top: 5px;
  font-size: 16px;
}

.container {
  background-color: white;
  padding: 20px;
  border-radius: 10px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
  width: 90%;
  max-width: 500px;
  text-align: center;
}

#timeDisplay {
  font-size: 48px;
  margin-bottom: 20px;
  font-weight: bold;
  color: #333;
}

.buttons {
  display: flex;
  justify-content: space-around;
}

button {
  padding: 10px 20px;
  font-size: 18px;
  background-color: #ddd;
  color: black;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  transition: background-color 0.3s ease;
  flex: 1;
  margin: 0 10px;
}

button.primary {
  background-color: #4CAF50;
  color: white;
}

button.primary:hover {
  background-color: #45a049;
}

button:disabled {
  background-color: #ccc;
  cursor: not-allowed;
}

@media (max-width: 400px) {
  .header, .container {
      width: 90%;
      margin: 0;
      border-radius: 0;
  }

  .header {
      padding: 15px;
  }

  .container {
      padding: 15px;
  }

  #timeDisplay {
      font-size: 36px;
  }

  button {
      font-size: 16px;
  }
}