body { font-family:Arial, sans-serif;justify-content:center;align-items:center;height:100vh;margin:0;} .calculator { text-align:center;padding:20px;border:1px solid #ccc;border-radius:5px;} input[type="number"] { margin:10px 0;padding:8px;border:1px solid #ccc;border-radius:4px;display:block;width:calc(100% - 22px);} button { padding:10px 20px;background-color:#007BFF;color:white;border:none;border-radius:5px;cursor:pointer;margin-top:10px;} button:hover { background-color:#0056b3;} #result { margin-top:20px;font-size:20px;}