body {
  font-family: Arial, sans-serif;
  text-align: center;
  background: #f5f7fa;
  color: #333;
  padding: 50px 20px;
  transition: background 0.3s, color 0.3s;
}

.container {
  max-width: 500px;
  margin: auto;
  padding: 20px;
  background: #ffffff;
  border-radius: 15px;
  box-shadow: 0 4px 15px rgba(0,0,0,0.1);
}

h1 {
  color: #4a4a4a;
}

button {
  padding: 10px 20px;
  font-size: 16px;
  margin: 5px;
  cursor: pointer;
  border-radius: 8px;
  border: none;
  background-color: #4caf50;
  color: white;
  transition: background 0.3s;
}

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

.timer-container {
  margin-top: 20px;
}

.dark-mode {
  background: #1e1e1e;
  color: #f5f5f5;
}

.dark-mode .container {
  background: #333;
}