body {
    font-family: Arial, sans-serif;
    background-color: #d1e7f8;
  }
  
  h1 {
    text-align: center;
  }
  
  .intro-text {
    text-align: center;
    margin-bottom: 20px;
  }
  
  .calculator {
    width: 70%;
    max-width: 400px;
    border: 1px solid black;
    padding: 10px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    margin: auto;
  }
  
  .display {
    width: 100%;
    text-align: right;
    margin-bottom: 10px;
  }
  
  .display input {
    font-size: 24px;
    border: none;
    background-color: #f2f2f2;
    padding: 5px;
    box-sizing: border-box;
    width: 100%;
  }
  
  .buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    width: 100%;
  }
  
  button {
    margin: 5px;
    padding: 5px;
    background-color: #ccc;
    border: none;
    border-radius: 5px;
    font-size: 16px;
    width: 40px;
    height: 40px;
    box-sizing: border-box;
  }
  
  button:hover {
    cursor: pointer;
    background-color: #ddd;
  }
  
  /* Media queries */
  @media (max-width: 600px) {
    .calculator {
      width: 95%;
    }
  }