.rtb-form{max-width:720px;margin:1rem auto;padding:1rem;border:1px solid #eee;border-radius:8px}
.rtb-grid{display:grid;grid-template-columns:repeat(2,minmax(200px,1fr));gap:.75rem}
.rtb-row{display:flex;flex-direction:column}
.rtb-row label{font-weight:600;margin-bottom:.25rem}
.rtb-row input,.rtb-row textarea{padding:.55rem;border:1px solid #ccc;border-radius:6px;width:100%}
.rtb-row.rtb-span{grid-column:1 / -1}
.rtb-actions{margin-top:1rem}
.rtb-submit{padding:.6rem 1rem;border:0;border-radius:6px;background:#111;color:#fff;cursor:pointer}
.rtb-fine{margin-top:.5rem;font-size:.9em;opacity:.8}
.rtb-success{max-width:720px;margin:1rem auto;padding:1rem;background:#f5fff5;border:1px solid #d6f5d6;border-radius:8px}
.rtb-error{max-width:720px;margin:1rem auto;padding:1rem;background:#fff5f5;border:1px solid #f5d6d6;border-radius:8px}
@media (max-width:640px){ .rtb-grid{grid-template-columns:1fr} }
@media (prefers-color-scheme: dark){
  .rtb-form{border-color:#333;background:#111}
  .rtb-submit{background:#eee;color:#111}
}