body {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  background: linear-gradient(135deg, #1f1c2c, #928dab);
}

.calculator {
  background: #2c2c2c;
  padding: 20px;
  border-radius: 15px;
  box-shadow: 0 10px 25px rgba(0,0,0,0.5);
}

#display {
  width: 100%;
  height: 60px;
  font-size: 24px;
  text-align: right;
  margin-bottom: 10px;
  padding: 10px;
  border: none;
  border-radius: 5px;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 70px);
  gap: 10px;
}

button {
  height: 60px;
  font-size: 18px;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  background: #444;
  color: white;
}

button:hover {
  background: #666;
}