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

.calculator {
  background-color: #fff;
  padding: 20px;
  border-radius: 5px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
  text-align: center;
}

.designer {
  font-size: 14px;
  color: #888;
  margin-top: 5px;
}

.display {
  margin-bottom: 10px;
}

.display input {
  width: 100%;
  font-size: 24px;
  padding: 5px;
  text-align: right;
  border: 1px solid #ccc;
  border-radius: 3px;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-gap: 5px;
}

.buttons button {
  font-size: 18px;
  padding: 10px;
  background-color: #f0f0f0;
  border: none;
  border-radius: 3px;
  cursor: pointer;
}

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