.calculator{max-width:400px;margin:0 auto;padding:20px;border:1px solid #ccc;border-radius:5px;background-color:#f5f5f5}.calculator label{display:block;text-align:left;margin-top:10px}.calculator input{width:100%;padding:5px;margin-top:5px}.calculator button{width:100%;padding:10px;margin-top:10px;background-color:#007bff;color:#fff;border:none;border-radius:5px;cursor:pointer}.calculator button:hover{background-color:#0056b3}#result{margin-top:10px}.calculator span{font-weight:700}