body {
  background: linear-gradient(135deg, #00bcd4, #8e24aa);
  font-family: Arial, sans-serif;
}

.calculator {
  background: #ffffff;
  width: 300px;
  border-radius: 8px;
}

.screen input {
  height: 60px;
  font-size: 24px;
  border: none;
  background: #f1f3f4;
  border-radius: 5px;
  padding: 10px;
}

.buttons .btn {
  font-size: 20px;
  height: 60px;
  border-radius: 5px;
}