:root {
  --bg: #f4f5f7; --card: #ffffff; --fg: #1b1f24; --muted: #5b6673; --border: #dfe3e8;
  --accent: #0b72b5; --accent-fg: #ffffff; --accent-soft: #e4f1fa;
  --ok: #1a7f37; --ok-bg: #e3f4e7; --bad: #c62828; --bad-bg: #fdeceb; --flag: #c98a00;
  --radius: 14px;
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1216; --card: #181c22; --fg: #e6e9ed; --muted: #9aa5b1; --border: #2b313a;
    --accent: #5aa9f0; --accent-fg: #0b1620; --accent-soft: #15293b;
    --ok: #4cc26a; --ok-bg: #12301c; --bad: #ff7b72; --bad-bg: #3a1716; --flag: #f0b93a;
  }
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--fg);
  font: 16px/1.5 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}
button { font: inherit; color: inherit; }
[hidden] { display: none !important; }
a { color: var(--accent); }
kbd {
  font: 0.8em ui-monospace, SFMono-Regular, Menlo, monospace;
  border: 1px solid var(--border); border-radius: 4px; padding: 0 0.3em; background: var(--card);
}

/* ── header ─────────────────────────────────────────────── */
.top {
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
  max-width: 1120px; margin: 0 auto; padding: 14px 16px 6px;
}
.brand { display: flex; align-items: center; gap: 10px; min-width: 0; }
.brand > div { min-width: 0; }
.brand-mark {
  flex: none; width: 34px; height: 34px; border-radius: 9px;
  background:
    repeating-linear-gradient(60deg, transparent 0 9px, #fff 9px 18px),
    repeating-linear-gradient(-60deg, #0b72b5 0 9px, #8fc7ea 9px 18px);
  background-blend-mode: normal; box-shadow: inset 0 0 0 1px rgba(0, 0, 0, .12);
}
.brand h1 { margin: 0; font-size: 1.05rem; line-height: 1.2; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.brand p { margin: 2px 0 0; font-size: .8rem; color: var(--muted); }
.land {
  max-width: 100%; min-height: 26px; padding: 1px 4px; border-radius: 7px; cursor: pointer;
  border: 1px solid var(--border); background: var(--card); color: var(--fg); font: inherit; font-weight: 600;
}
.land:hover:not(:disabled) { border-color: var(--accent); }
.land:disabled { opacity: .6; cursor: default; }

/* ── buttons ────────────────────────────────────────────── */
.btn {
  min-height: 44px; padding: 0 16px; border-radius: 11px; cursor: pointer;
  border: 1px solid var(--border); background: var(--card); font-weight: 600; font-size: .95rem;
  white-space: nowrap;
}
.btn:hover { border-color: var(--accent); }
.btn:disabled { opacity: .45; cursor: default; border-color: var(--border); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-fg); }
.btn.ghost { background: transparent; }
.btn.danger { color: var(--bad); }
.btn.translate { border-color: var(--accent); color: var(--accent); background: var(--accent-soft); }
.btn.translate[aria-pressed="true"] { background: var(--accent); color: var(--accent-fg); }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }

/* ── layout ─────────────────────────────────────────────── */
.layout {
  display: grid; grid-template-columns: minmax(0, 1fr) 340px; gap: 20px; align-items: start;
  max-width: 1120px; margin: 0 auto; padding: 10px 16px 32px;
}
.main { min-width: 0; }
.card {
  background: var(--card); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 20px; box-shadow: 0 1px 2px rgba(0, 0, 0, .04);
}
.card.empty { text-align: center; color: var(--muted); padding: 40px 20px; }

.banner {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 10px;
  background: var(--accent-soft); border: 1px solid var(--accent); border-radius: var(--radius);
  padding: 12px 16px; margin-bottom: 12px; font-weight: 600;
}
.banner.pass { background: var(--ok-bg); border-color: var(--ok); }
.banner.fail { background: var(--bad-bg); border-color: var(--bad); }
.banner small { display: block; font-weight: 400; color: var(--muted); }
.banner-actions { display: flex; gap: 8px; }

/* ── question card ──────────────────────────────────────── */
.card-head { display: flex; align-items: center; gap: 8px; min-height: 36px; }
.q-pos { color: var(--muted); font-size: .9rem; font-weight: 600; }
.tag {
  font-size: .72rem; font-weight: 700; letter-spacing: .03em; text-transform: uppercase;
  color: var(--accent); background: var(--accent-soft); border-radius: 999px; padding: 2px 9px;
}
.flag {
  margin-left: auto; width: 44px; height: 44px; border: 0; background: none; cursor: pointer;
  font-size: 1.5rem; line-height: 1; color: var(--muted); border-radius: 10px;
}
.flag[aria-pressed="true"] { color: var(--flag); }
.q-text { margin: 6px 0 16px; font-size: 1.3rem; line-height: 1.35; font-weight: 650; overflow-wrap: anywhere; }
.q-fig { margin: 0 0 16px; background: #fff; border: 1px solid var(--border); border-radius: 10px; padding: 8px; text-align: center; }
.q-fig img { max-width: 100%; height: auto; display: block; margin: 0 auto; cursor: zoom-in; }
.q-fig.zoom { overflow-x: auto; }
.q-fig.zoom img { max-width: none; cursor: zoom-out; }

.answers { list-style: none; margin: 0; padding: 0; display: grid; gap: 10px; }
.answer {
  display: flex; align-items: flex-start; gap: 12px; width: 100%; min-height: 52px; text-align: left;
  padding: 13px 14px; border-radius: 12px; border: 1.5px solid var(--border); background: var(--card);
  cursor: pointer; font-size: 1.02rem; line-height: 1.4; overflow-wrap: anywhere;
}
.answer .dot {
  flex: none; width: 22px; height: 22px; margin-top: 1px; border-radius: 50%; border: 2px solid var(--muted);
  display: grid; place-items: center; font-size: .8rem; font-weight: 800; line-height: 1; color: transparent;
}
.answer:not(:disabled):hover { border-color: var(--accent); }
.answer:disabled { cursor: default; color: inherit; }
.answer.chosen { border-color: var(--accent); background: var(--accent-soft); }
.answer.chosen .dot { border-color: var(--accent); background: var(--accent); box-shadow: inset 0 0 0 4px var(--accent-soft); }
.answer.correct { border-color: var(--ok); background: var(--ok-bg); }
.answer.correct .dot { border-color: var(--ok); background: var(--ok); color: #fff; }
.answer.wrong { border-color: var(--bad); background: var(--bad-bg); }
.answer.wrong .dot { border-color: var(--bad); background: var(--bad); color: #fff; }

.feedback { margin: 14px 0 0; font-weight: 700; }
.feedback.ok { color: var(--ok); }
.feedback.bad { color: var(--bad); }
.card-foot { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-top: 18px; }
.tr-note { color: var(--muted); font-size: .85rem; }
.card-foot #btn-retry { margin-left: auto; }

.pager { display: flex; gap: 10px; margin-top: 14px; }
.pager .nav { flex: 1; }
.pager .list-toggle { display: none; }
.source { color: var(--muted); font-size: .8rem; margin: 18px 4px 0; }

/* ── side panel ─────────────────────────────────────────── */
.side {
  position: sticky; top: 12px; background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 16px; display: grid; gap: 14px;
}
.side-head { display: flex; align-items: center; justify-content: space-between; }
.side-close { display: none; min-height: 36px; padding: 0 10px; }
.bar { display: flex; height: 10px; border-radius: 999px; overflow: hidden; background: var(--border); }
.bar i { display: block; height: 100%; }
#bar-ok { background: var(--ok); }
#bar-bad { background: var(--bad); }
.stats p { margin: 8px 0 0; font-size: .88rem; color: var(--muted); }

.filters { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 10px; }
.filters button {
  min-height: 36px; padding: 0 12px; border-radius: 999px; border: 1px solid var(--border);
  background: transparent; cursor: pointer; font-size: .85rem; font-weight: 600;
}
.filters button[aria-pressed="true"] { background: var(--accent); border-color: var(--accent); color: var(--accent-fg); }
.check { display: flex; align-items: center; gap: 8px; font-size: .9rem; min-height: 32px; cursor: pointer; }
.check input { width: 18px; height: 18px; accent-color: var(--accent); }

.grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(38px, 1fr)); gap: 5px;
  max-height: 46vh; overflow-y: auto; padding: 3px; margin: -3px;
}
.chip {
  position: relative; height: 36px; border-radius: 8px; border: 1px solid var(--border); background: transparent;
  cursor: pointer; font-size: .78rem; font-weight: 600; padding: 0; font-variant-numeric: tabular-nums;
}
.chip.ok { background: var(--ok-bg); border-color: var(--ok); color: var(--ok); }
.chip.bad { background: var(--bad-bg); border-color: var(--bad); color: var(--bad); }
.chip.chosen { background: var(--accent-soft); border-color: var(--accent); color: var(--accent); }
.chip.cur { outline: 2.5px solid var(--fg); outline-offset: 1px; }
.chip.flagged::after {
  content: ""; position: absolute; top: 3px; right: 3px; width: 6px; height: 6px; border-radius: 50%; background: var(--flag);
}
.keys { margin: 0; font-size: .78rem; color: var(--muted); }
.backdrop { display: none; }

/* ── mobile ─────────────────────────────────────────────── */
@media (max-width: 899px) {
  .layout { display: block; padding: 8px 16px calc(92px + env(safe-area-inset-bottom)); }
  .top { padding-top: calc(10px + env(safe-area-inset-top)); }
  .brand-count { display: none; }
  .land { min-height: 32px; font-size: 16px; }  /* 16px keeps iOS from zooming in on focus */
  .brand h1 { font-size: .95rem; white-space: normal; }
  .top .btn { padding: 0 12px; font-size: .9rem; }
  .card { padding: 16px; }
  .q-text { font-size: 1.18rem; }

  .pager {
    position: fixed; left: 0; right: 0; bottom: 0; z-index: 5; margin: 0;
    padding: 10px 16px calc(10px + env(safe-area-inset-bottom));
    background: var(--bg); border-top: 1px solid var(--border);
  }
  .pager .nav { min-height: 50px; }
  .pager .list-toggle { display: block; flex: 1.2; font-variant-numeric: tabular-nums; }

  .backdrop { display: block; position: fixed; inset: 0; z-index: 9; background: rgba(0, 0, 0, .45); }
  .side {
    position: fixed; left: 0; right: 0; bottom: 0; top: auto; z-index: 10; max-height: 86vh; overflow-y: auto;
    border-radius: 18px 18px 0 0; border-bottom: 0; padding-bottom: calc(16px + env(safe-area-inset-bottom));
    transform: translateY(105%); transition: transform .22s ease; visibility: hidden;
  }
  .side.open { transform: none; visibility: visible; }
  .side-close { display: block; }
  .grid { max-height: none; grid-template-columns: repeat(auto-fill, minmax(42px, 1fr)); }
  .chip { height: 42px; font-size: .85rem; }
  .keys { display: none; }
}
@media (max-width: 380px) {
  .pager .nav span { display: none; }
  .top .btn { padding: 0 12px; font-size: .88rem; }
}
@media (prefers-reduced-motion: reduce) { .side { transition: none; } }