:root {
    --bg: #f6f7f9; --card: #ffffff; --text: #1a1d21; --muted: #5f6672; --border: #dfe3e8;
    --accent: #5b3df5; --accent-soft: #ece8ff; --ok: #1f8a4c; --ok-soft: #e3f5ea; --bad: #c62828; --bad-soft: #fde8e8;
    --warn: #b7791f; --warn-soft: #fff4dd; --code-bg: #f0f2f5; --shadow: 0 1px 2px rgba(0,0,0,.06), 0 4px 16px rgba(0,0,0,.04);
  }
  @media (prefers-color-scheme: dark) {
    :root { --bg: #111417; --card: #1a1f24; --text: #e7eaee; --muted: #9aa3ae; --border: #2c333b;
      --accent: #9b8bff; --accent-soft: #2a2350; --ok: #4cc07a; --ok-soft: #173124; --bad: #ff6b6b; --bad-soft: #3a1d1d;
      --warn: #e2b04a; --warn-soft: #3a2f14; --code-bg: #0f1215; --shadow: 0 1px 2px rgba(0,0,0,.4); }
  }
  * { box-sizing: border-box; }
  body { margin: 0; background: var(--bg); color: var(--text); font: 15px/1.55 ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif; -webkit-font-smoothing: antialiased; }
  .wrap { max-width: 860px; margin: 0 auto; padding: 24px 16px 64px; }
  header { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 20px; }
  header h1 { font-size: 20px; margin: 0; letter-spacing: -.01em; }
  header h1 span { color: var(--accent); }
  .card { background: var(--card); border: 1px solid var(--border); border-radius: 14px; padding: 20px; box-shadow: var(--shadow); }
  .card + .card { margin-top: 16px; }
  h2 { font-size: 15px; margin: 0 0 10px; color: var(--muted); text-transform: uppercase; letter-spacing: .06em; }
  .chips { display: flex; flex-wrap: wrap; gap: 8px; }
  .chip { border: 1px solid var(--border); background: transparent; color: var(--text); padding: 6px 12px; border-radius: 999px; cursor: pointer; font-size: 14px; }
  .chip.on { background: var(--accent-soft); border-color: var(--accent); color: var(--accent); font-weight: 600; }
  .chip small { color: var(--muted); font-weight: 400; margin-left: 4px; }
  .row { display: flex; flex-wrap: wrap; gap: 16px 28px; align-items: flex-end; }
  .field label { display: block; font-size: 12px; color: var(--muted); margin-bottom: 4px; }
  select, input[type=number] { background: var(--card); color: var(--text); border: 1px solid var(--border); border-radius: 8px; padding: 7px 10px; font-size: 14px; }
  .btn { border: 1px solid var(--border); background: var(--card); color: var(--text); padding: 10px 16px; border-radius: 10px; cursor: pointer; font-size: 15px; font-weight: 600; }
  .btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
  .btn.ghost { background: transparent; }
  .btn:disabled { opacity: .45; cursor: not-allowed; }
  .actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 16px; }
  .stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(120px, 1fr)); gap: 12px; }
  .stat { padding: 12px; border-radius: 10px; background: var(--bg); }
  .stat b { display: block; font-size: 22px; }
  .stat span { color: var(--muted); font-size: 12px; }
  .muted { color: var(--muted); }
  .topbar { display: flex; justify-content: space-between; align-items: center; gap: 12px; margin-bottom: 12px; flex-wrap: wrap; }
  .progress { height: 6px; background: var(--border); border-radius: 999px; overflow: hidden; margin-bottom: 16px; }
  .progress i { display: block; height: 100%; background: var(--accent); transition: width .2s; }
  .badges { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 10px; }
  .badge { font-size: 11px; text-transform: uppercase; letter-spacing: .05em; padding: 3px 8px; border-radius: 6px; background: var(--accent-soft); color: var(--accent); font-weight: 700; }
  .badge.tier { background: var(--warn-soft); color: var(--warn); }
  .badge.kind { background: var(--bg); color: var(--muted); }
  .q { font-size: 17px; font-weight: 600; margin: 0 0 12px; line-height: 1.45; }
  pre { background: var(--code-bg); border: 1px solid var(--border); border-radius: 10px; padding: 12px 14px; overflow-x: auto; font: 13px/1.5 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; margin: 0 0 14px; }
  .options { display: grid; gap: 8px; }
  .opt { text-align: left; display: flex; gap: 12px; align-items: flex-start; border: 1px solid var(--border); background: var(--card); color: var(--text); padding: 12px 14px; border-radius: 10px; cursor: pointer; font-size: 15px; line-height: 1.4; }
  .opt:hover:not(:disabled) { border-color: var(--accent); }
  .opt .k { flex: none; width: 24px; height: 24px; border-radius: 6px; background: var(--bg); color: var(--muted); font-weight: 700; font-size: 13px; display: grid; place-items: center; }
  .opt.sel { border-color: var(--accent); background: var(--accent-soft); }
  .opt.ok { border-color: var(--ok); background: var(--ok-soft); }
  .opt.bad { border-color: var(--bad); background: var(--bad-soft); }
  .opt:disabled { cursor: default; }
  .feedback { margin-top: 14px; padding: 14px; border-radius: 10px; border: 1px solid var(--border); background: var(--bg); }
  .feedback.ok { border-color: var(--ok); } .feedback.bad { border-color: var(--bad); }
  .feedback h3 { margin: 0 0 6px; font-size: 14px; }
  .feedback.ok h3 { color: var(--ok); } .feedback.bad h3 { color: var(--bad); }
  .feedback a { color: var(--accent); }
  .timer { font-variant-numeric: tabular-nums; font-weight: 700; padding: 6px 10px; border-radius: 8px; background: var(--bg); }
  .timer.low { background: var(--bad-soft); color: var(--bad); }
  table { width: 100%; border-collapse: collapse; font-size: 14px; }
  th, td { text-align: left; padding: 8px 6px; border-bottom: 1px solid var(--border); }
  th { color: var(--muted); font-weight: 600; font-size: 12px; text-transform: uppercase; letter-spacing: .05em; }
  .score { font-size: 40px; font-weight: 800; letter-spacing: -.02em; }
  .kbd { font: 12px ui-monospace, monospace; border: 1px solid var(--border); border-bottom-width: 2px; border-radius: 5px; padding: 1px 6px; color: var(--muted); }
  .hint { font-size: 13px; color: var(--muted); margin-top: 10px; }
  .flag { color: var(--warn); }
  .feedback .explain { margin-top: 4px; }
  .feedback .docs-actions { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; margin-top: 10px; }
  .btn.small { padding: 7px 12px; font-size: 13px; }
  .overlay { position: fixed; inset: 0; background: rgba(0,0,0,.35); z-index: 20; opacity: 0; transition: opacity .15s; }
  .panel { position: fixed; top: 0; right: 0; height: 100vh; width: min(620px, 96vw); background: var(--card); border-left: 1px solid var(--border); box-shadow: var(--shadow); z-index: 21; transform: translateX(100%); transition: transform .2s; display: flex; flex-direction: column; }
  .panel.open, .overlay.open { transform: none; opacity: 1; }
  .panel-head { display: flex; align-items: center; gap: 10px; padding: 12px 16px; border-bottom: 1px solid var(--border); }
  .panel-head .src { font-size: 12px; color: var(--muted); flex: 1; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
  .panel-head a { color: var(--accent); font-size: 13px; text-decoration: none; white-space: nowrap; }
  .panel-body { padding: 16px 20px 40px; overflow-y: auto; }
  [hidden] { display: none !important; }
  @media (max-width: 520px) { .wrap { padding: 14px 10px 48px; } .card { padding: 16px; } .q { font-size: 16px; } }