body {
    font-family: Arial, sans-serif;
    background-color: #f3f4f6;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
  }
  
  .calculator {
    width: 300px;
    background: #e3f2fd;
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
  }
  
  .display {
    background: #90caf9;
    border-radius: 10px 10px 0 0;
    padding: 10px;
    text-align: right;
  }
  
  #calc-display {
    width: 100%;
    font-size: 1.5rem;
    padding: 10px;
    border: none;
    background: none;
    text-align: right;
    color: #000;
  }
  
  .buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 5px;
    padding: 10px;
  }
  
  button {
    background: #bbdefb;
    border: none;
    border-radius: 5px;
    font-size: 1.2rem;
    padding: 15px;
    cursor: pointer;
    transition: background-color 0.2s ease;
  }
  
  button:hover {
    background: #90caf9;
  }
  
  button:active {
    background: #42a5f5;
  }