body{font-family:Arial,sans-serif;background-color:#f4f4f4;margin:0;padding:0;display:flex;justify-content:center;align-items:center;height:100vh}.calculator{background:#fff;padding:20px;border-radius:10px;box-shadow:0 0 10px rgba(0,0,0,.1);width:100%;max-width:400px}h1{text-align:center;margin-bottom:20px}.unit-switch{display:flex;justify-content:center;margin-bottom:20px}.unit-switch button{padding:10px 20px;border:none;background:#007bff;color:#fff;cursor:pointer;border-radius:5px;margin:0 5px}.unit-switch button.active{background:#0056b3}form{display:flex;flex-direction:column}label{margin-bottom:5px;font-weight:700}input,select{padding:10px;margin-bottom:15px;border:1px solid #ccc;border-radius:5px}button[type=submit]{padding:10px;background:#28a745;color:#fff;border:none;border-radius:5px;cursor:pointer}button[type=submit]:hover{background:#218838}#results{margin-top:20px}.hidden{display:none}