body {
  background: #f2f2f2;
  font-family: Arial, sans-serif;
  text-align: center;
}

h2 {
  margin-top: 20px;
}

.calculator {
  width: 280px;
  margin: 20px auto;
  background: #ffffff;
  padding: 15px;
  border-radius: 6px;
  border: 1px solid #ccc;
}

#display {
  width: 100%;
  height: 45px;
  font-size: 20px;
  text-align: right;
  margin-bottom: 10px;
  padding-right: 8px;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 6px;
}

button {
  padding: 12px;
  font-size: 16px;
  cursor: pointer;
}

.buttons button:nth-child(4n) {
  background: #ff9900;
  color: white;
}

.buttons button:first-child {
  background: #ff5252;
  color: white;
}

.equal {
  grid-row: span 2;
  background: #00fc08;
  color: white;
  font-size: 18px;
}