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

#calc-grid {
  display: grid;
  grid-template-columns: repeat(4, 100px);
  grid-template-rows: repeat(6, 100px);
  gap: 10px;
  background-color: #fff;
  padding: 20px;
  border-radius: 10px;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.2);
}

#display {
  grid-column: span 4;
  background-color: #e0e0e0;
  display: flex;
  justify-content: flex-end;
  align-items: center;
  padding: 0 10px;
  font-size: 2rem;
  border-radius: 5px;
}

button {
  font-size: 1.5rem;
  background-color: #f9f9f9;
  border: 1px solid #ccc;
  border-radius: 5px;
  cursor: pointer;
}

button:hover {
  background-color: #e0e0e0;
}

.span-two {
  grid-column: span 2;
}