.container{max-width:500px;margin:30px auto;padding:20px;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;color:#333}.container h1{font-size:24px;margin-bottom:10px;display:flex;align-items:center;gap:8px}.container p{color:#666;margin-bottom:25px;line-height:1.5}.form-group{margin-bottom:15px;display:flex}.form-group label{width:180px;padding:10px;background-color:#f8f8f8;border:1px solid #ddd;border-right:none;display:flex;align-items:center}.form-control{flex:1;padding:10px;border:1px solid #ddd;font-size:16px;outline:none}.btn-calculate{width:100%;padding:15px;background-color:#000;color:#fff;border:none;cursor:pointer;font-size:16px;margin-top:10px;transition:background-color 0.3s}.btn-calculate:hover{background-color:#333}.result{margin-top:20px;padding:15px;background-color:#f8f8f8;border:1px solid #ddd;display:none}.result.show{display:block}.error{color:#d9534f;margin-top:10px;display:none}.error.show{display:block}