body {
  font-family: Arial, sans-serif;
  background: #f4f4f4;
  text-align: center;
  padding: 40px;
}
.calculadora {
  background: #fff;
  border-radius: 10px;
  padding: 30px;
  display: inline-block;
  box-shadow: 0 0 10px rgba(0,0,0,0.1);
}
input {
  padding: 10px;
  margin: 10px;
  width: 80px;
  font-size: 16px;
}
button {
  padding: 10px 15px;
  margin: 5px;
  font-size: 16px;
  cursor: pointer;
  border: none;
  border-radius: 5px;
  background-color: #007bff;
  color: white;
}
button:hover {
  background-color: #0056b3;
}
.resultado {
  margin-top: 20px;
  font-size: 20px;
  font-weight: bold;
}