.calculator {
  width: 300px;
  margin: 50px auto;
  padding: 20px;
  border: 1px solid #ccc;
  border-radius: 10px;
  background-color: #f9f9f9;
  font-family: Arial, sans-serif;
}

#display {
  width: 100%;
  height: 50px;
  font-size: 24px;
  text-align: right;
  margin-bottom: 10px;
  border: 1px solid #aaa;
  border-radius: 5px;
  padding: 5px;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

button {
  padding: 15px;
  font-size: 18px;
  border: 1px solid #ccc;
  border-radius: 5px;
  background-color: #fff;
  cursor: pointer;
}

button:hover {
  background-color: #e0e0e0;
}

button:active {
  background-color: #ccc;
}