:root {
    --bg: #f4f2ee; --card: #ffffff; --ink: #1b2a3a; --muted: #5d6b79; --line: #e3e0da;
    --accent: #1b2a3a; --ok: #1f7a4d; --ok-bg: #e6f4ec; --bad: #b3261e; --bad-bg: #fbeae8;
  }
  @media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
      --bg: #12171d; --card: #1b222b; --ink: #e8ecf0; --muted: #9aa6b2; --line: #2c3540;
      --accent: #e8ecf0; --ok: #6fd3a0; --ok-bg: #16342a; --bad: #f2a29b; --bad-bg: #3a1f1d;
    }
  }
  :root[data-theme="dark"] {
    --bg: #12171d; --card: #1b222b; --ink: #e8ecf0; --muted: #9aa6b2; --line: #2c3540;
    --accent: #e8ecf0; --ok: #6fd3a0; --ok-bg: #16342a; --bad: #f2a29b; --bad-bg: #3a1f1d;
  }
  * { box-sizing: border-box; }
  body { margin: 0; background: var(--bg); color: var(--ink);
    font: 16px/1.5 system-ui, -apple-system, "Segoe UI", Inter, sans-serif; }
  main { max-width: 960px; margin: 0 auto; padding: 32px 16px 48px; }
  .eyebrow { font-size: 13px; letter-spacing: .08em; text-transform: uppercase; color: var(--muted); margin: 0 0 4px; }
  h1 { font-size: clamp(26px, 4vw, 36px); margin: 0 0 20px; letter-spacing: -.01em; }
  .stage { background: var(--card); border: 1px solid var(--line); border-radius: 14px; overflow: hidden; }
  video { display: block; width: 100%; aspect-ratio: 16/9; background: #000; }
  .panel { padding: 24px; }
  .hidden { display: none !important; }
  .progress { font-size: 13px; color: var(--muted); margin-bottom: 6px; }
  .q { font-size: 20px; font-weight: 600; margin: 0 0 16px; }
  .opts { display: grid; gap: 10px; }
  .opt { text-align: left; font: inherit; color: var(--ink); background: transparent;
    border: 1px solid var(--line); border-radius: 10px; padding: 12px 14px; cursor: pointer; }
  .opt:hover:not(:disabled) { border-color: var(--muted); }
  .opt:disabled { cursor: default; }
  .opt.correct { border-color: var(--ok); background: var(--ok-bg); }
  .opt.wrong { border-color: var(--bad); background: var(--bad-bg); }
  .feedback { margin: 16px 0 0; padding: 12px 14px; border-radius: 10px; background: var(--bg); }
  .row { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 18px; }
  .btn { font: inherit; font-weight: 600; border: 0; border-radius: 10px; padding: 11px 18px; cursor: pointer;
    background: var(--accent); color: var(--bg); }
  .btn.ghost { background: transparent; color: var(--ink); border: 1px solid var(--line); }
  .score { font-size: 44px; font-weight: 700; margin: 4px 0; }
  .hint { color: var(--muted); margin: 0; }
  footer { margin-top: 20px; font-size: 13px; color: var(--muted); }