body {
  background-color: #3c3c3c;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  font-family: Arial, sans-serif;
}

.calculator {
  background-color: #d9d9d9;
  padding: 20px;
  border-radius: 10px;
  box-shadow: 0 0 15px rgba(0, 0, 0, 0.5);
}

.display {
  width: 100%;
  height: 50px;
  font-size: 24px;
  margin-bottom: 10px;
  text-align: right;
  padding-right: 10px;
  border: none;
  border-radius: 5px;
  box-shadow: inset 0 0 8px #aaa;
  background: white;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 60px);
  grid-gap: 10px;
}

button {
  height: 60px;
  font-size: 20px;
  border: none;
  border-radius: 5px;
  background: #f1f1f1;
  box-shadow: inset 0 2px #ffffff, inset 0 -2px #cccccc;
  cursor: pointer;
}

button.operator {
  background: #2e2e2e;
  color: white;
}

button.equal {
  background: #2e2e2e;
  color: white;
}

button.clear {
  background: #cc0000;
  color: white;
}