.calculator{background-color:#fff;text-align:center;border:1px solid #ccc;padding:20px;border-radius:5px;width:300px;margin:0 auto}.calculator label{display:block;margin-bottom:5px}.calculator select,input{width:100%;padding:5px;margin-bottom:10px}.calculator button{color:#fff;border:none;padding:10px 20px;border-radius:5px;cursor:pointer}.calculator button:hover{background-color:#0056b3}#result{font-weight:700}