:root{font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial;}
    body{display:flow-root;align-items:center;justify-content:center;min-height:100vh;background:linear-gradient(135deg,#f6f8ff,#eef9f1);margin:0;padding:20px}
    .card{background:white;padding:22px;border-radius:12px;box-shadow:0 8px 24px rgba(20,30,50,0.08);width:100%;max-width:420px}
    h1{font-size:20px;margin:0 0 12px}
    .row{display:flex;gap:10px;margin-bottom:12px}
    input[type="number"]{flex:1;padding:10px;border:1px solid #d6dbe8;border-radius:8px;font-size:16px}
    .actions{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:12px}
    button{flex:1;min-width:90px;padding:10px;border-radius:8px;border:0;background:#2b6ef6;color:white;font-weight:600;cursor:pointer}
    button.secondary{background:#6b7280}
    .result{padding:12px;border-radius:8px;background:#f3f4f6;border:1px dashed #e5e7eb;font-size:16px;min-height:44px;display:flex;align-items:center}
    .small{font-size:13px;color:#6b7280;margin-top:8px}
    .error{color:#b91c1c;font-weight:700}
    a.btn {
  display: inline-block;
  margin: 10px;
  padding: 10px 15px;
  text-decoration: none;
  color: white;
  background-color: #0d1a10;
  border-radius: 5px;
}

a.btn:hover {
  background-color: #060f08;}