body {
  font-family: Arial, sans-serif;
  text-align: center;
  background: #121212;
  color: #fff;
}

.container {
  margin-top: 50px;
}

#box {
  width: 150px;
  height: 150px;
  background-color: #4caf50;
  margin: 30px auto;
  display: none;
  cursor: pointer;
  border-radius: 10px;
}

button {
  padding: 10px 20px;
  font-size: 16px;
  cursor: pointer;
  background-color: #1e88e5;
  color: white;
  border: none;
  border-radius: 5px;
}

button:hover {
  background-color: #1565c0;
}