:root { color-scheme: light; }
  * { box-sizing: border-box; }
  body {
    margin: 0; min-height: 100vh; display: flex; align-items: center; justify-content: center;
    padding: 24px; background: #eef1f5; color: #16202c;
    font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  }
  .card { width: 100%; max-width: 470px; background: #fff; border: 1px solid #e3e8ef; border-radius: 10px; overflow: hidden; }
  .band { background: #10243a; padding: 16px 26px; }
  .band b { display: block; font-size: 12px; font-weight: 700; letter-spacing: 2px; color: #fff; }
  .band span { display: block; font-size: 12px; font-weight: 700; letter-spacing: 2px; color: #d9b85c; margin-top: 3px; }
  .rule { height: 3px; background: #bf9b30; }
  .body { padding: 26px; }
  h1 { margin: 0 0 6px; font-size: 20px; }
  p.lead { margin: 0 0 20px; font-size: 14px; line-height: 1.6; color: #4b5a6d; }
  .btn {
    display: block; width: 100%; font-family: inherit; font-size: 15px; font-weight: 700;
    padding: 14px; border: 0; border-radius: 6px; background: #10243a; color: #fff;
    text-align: center; text-decoration: none;
  }
  .btn:hover { background: #17324e; }
  .btn:focus-visible { outline: 3px solid rgba(191,155,48,.6); outline-offset: 2px; }
  .btn.sec { background: #fff; color: #16202c; border: 1px solid #c9d4e0; margin-top: 10px; font-weight: 400; font-size: 13.5px; padding: 11px; }
  .btn.sec:hover { background: #f7f9fb; }
  .next { margin-top: 22px; padding: 14px 16px; background: #f7f9fb; border: 1px solid #e3e8ef; border-radius: 6px; }
  .next b { font-size: 13px; }
  .next ol { margin: 8px 0 0; padding-left: 20px; font-size: 13px; line-height: 1.75; color: #3c4757; }
  .foot { padding: 14px 26px; border-top: 1px solid #e3e8ef; background: #f7f9fb; font-size: 12px; color: #4b5a6d; line-height: 1.6; }
  .foot a { color: #1c6ea4; }
  @media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) { color-scheme: dark; }
    :root:not([data-theme="light"]) body { background: #0d1620; color: #e8edf3; }
    :root:not([data-theme="light"]) .card { background: #142231; border-color: #24394f; }
    :root:not([data-theme="light"]) p.lead, :root:not([data-theme="light"]) .foot { color: #9fb4c9; }
    :root:not([data-theme="light"]) .next { background: #0f1d28; border-color: #24394f; }
    :root:not([data-theme="light"]) .next ol { color: #b9cada; }
    :root:not([data-theme="light"]) .btn.sec { background: #142231; color: #e8edf3; border-color: #2d4a66; }
    :root:not([data-theme="light"]) .foot { background: #0f1d28; border-color: #24394f; }
  }
  form { display: grid; gap: 10px; }
  label { font-size: 13px; font-weight: 600; }
  input.code {
    font-family: 'IBM Plex Mono', ui-monospace, Consolas, monospace; font-size: 26px; letter-spacing: 6px;
    text-align: center; padding: 12px; border: 1px solid #c9d4e0; border-radius: 6px; width: 100%;
    background: #fff; color: #16202c;
  }
  input.code:focus-visible { outline: 3px solid rgba(191,155,48,.6); outline-offset: 1px; }
  .msg { min-height: 20px; margin: 4px 0 0; font-size: 13px; color: #b42318; line-height: 1.5; }
  .hint { font-size: 12.5px; color: #4b5a6d; line-height: 1.55; margin: 2px 0 0; }
  .server { margin-top: 16px; padding: 12px 14px; border: 1px solid #e3e8ef; border-radius: 6px; font-size: 12.5px; line-height: 1.7; }
  .server code { font-family: 'IBM Plex Mono', ui-monospace, Consolas, monospace; word-break: break-all; }
  [hidden] { display: none !important; }
  @media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) input.code { background: #0f1d28; color: #e8edf3; border-color: #2d4a66; }
    :root:not([data-theme="light"]) .msg { color: #ff8a80; }
    :root:not([data-theme="light"]) .hint { color: #9fb4c9; }
    :root:not([data-theme="light"]) .server { border-color: #24394f; }
  }