body {
  font-family: Arial, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  margin: 0;
  background-color: #f0f0f0;
}

.calculator {
  background-color: #333;
  padding: 20px;
  border-radius: 10px;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.3);
}

.display {
  width: 100%;
  height: 60px;
  font-size: 24px;
  text-align: right;
  padding: 0 15px;
  margin-bottom: 15px;
  border: none;
  border-radius: 5px;
  background-color: #000;
  color: white;
  box-sizing: border-box;
}

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

button {
  height: 60px;
  font-size: 18px;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  transition: background-color 0.2s;
}

.number,
.clear {
  background-color: #666;
  color: white;
}

.operator {
  background-color: #ff9500;
  color: white;
}

.equals {
  background-color: #ff9500;
  color: white;
}

button:hover {
  opacity: 0.8;
}

button:active {
  transform: scale(0.95);
}

.clear {
  grid-column: span 2;
}