body{font-family:Arial,sans-serif;text-align:center;background-color:#f4f4f4;padding:20px}.calculator{background-color:#fff;padding:20px;border:1px solid #ccc;border-radius:5px;box-shadow:0 0 5px rgba(0,0,0,.2);width:300px;margin:0 auto}.calculator input,button{width:100%;margin:10px 0;padding:10px}.calculator button{background-color:#0073e7;color:#fff;border:none;cursor:pointer}.calculator button:hover{background-color:#0055b3}#result{margin-top:20px}