.calculator{padding:20px}h4{color:#333}label{display:block;margin:10px 0 5px;font-weight:700}input,select{width:100%;padding:8px;margin-bottom:15px;border:1px solid #ccc;border-radius:4px}button{width:100%;padding:10px;background-color:#28a745;color:#fff;border:none;border-radius:4px;cursor:pointer}button:hover{background-color:#218838}#result{margin-top:20px;text-align:center;color:#333}.result-box{margin-top:10px;padding:15px;background-color:#e9ecef;border-radius:4px;font-size:1.2em;font-weight:700;display:inline-block}