:root {
  --bg: #f5f6f8;
  --surface: #ffffff;
  --text: #1c2230;
  --muted: #667085;
  --border: #dde1e7;
  --primary: #2f6fde;
  --primary-text: #ffffff;
  --ok: #1f9d55;
  --ok-bg: #e5f6ec;
  --ko: #d64545;
  --ko-bg: #fbe9e9;
  --warn: #c27a00;
  --radius: 12px;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12151b;
    --surface: #1b2029;
    --text: #e7eaf0;
    --muted: #98a2b3;
    --border: #2c3340;
    --primary: #5b8ef0;
    --ok: #4cc782;
    --ok-bg: #173325;
    --ko: #f07070;
    --ko-bg: #3a1d1f;
    --warn: #f0b247;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font: 16px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
}
button { font: inherit; color: inherit; cursor: pointer; }
[hidden] { display: none !important; }

.topbar {
  display: flex; align-items: center; justify-content: space-between;
  padding: calc(12px + env(safe-area-inset-top)) 16px 12px; background: var(--surface); border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 10;
}
.topbar .brand { background: none; border: 0; font-weight: 700; font-size: 1.1rem; }
.topbar nav button { background: none; border: 0; padding: 6px 10px; color: var(--muted); }
.topbar nav button:hover { color: var(--text); }
.topbar nav .lang { border: 1px solid var(--border); border-radius: 8px; margin-left: 6px; font-weight: 600; font-size: .85rem; }

main { max-width: 860px; margin: 0 auto; padding: 16px max(16px, env(safe-area-inset-right)) calc(64px + env(safe-area-inset-bottom)) max(16px, env(safe-area-inset-left)); }
/* Inside Telegram the native BackButton replaces the "Home" nav button. */
body.tg .topbar nav [data-nav="home"] { display: none; }
h2 { font-size: 1.1rem; margin: 28px 0 12px; }
.muted { color: var(--muted); }

.config label { display: inline-flex; gap: 8px; align-items: center; color: var(--muted); }
select { font: inherit; padding: 6px 10px; border-radius: 8px; border: 1px solid var(--border); background: var(--surface); color: var(--text); }

.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 12px; }
.card {
  display: flex; flex-direction: column; align-items: flex-start; gap: 4px; text-align: left;
  padding: 16px; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  transition: border-color .15s, transform .15s;
}
.card:hover:not(:disabled) { border-color: var(--primary); transform: translateY(-1px); }
.card:disabled { opacity: .5; cursor: not-allowed; }
.card-title { font-weight: 600; }
.card-sub { color: var(--muted); font-size: .9rem; }
.card-accent { border-left: 4px solid var(--primary); }
.card-warn { border-left: 4px solid var(--warn); }
.meter { width: 100%; height: 6px; background: var(--border); border-radius: 3px; overflow: hidden; margin-top: 6px; }
.meter > div { height: 100%; background: var(--ok); }

.quiz-head { display: flex; justify-content: space-between; color: var(--muted); font-size: .9rem; }
.progress { height: 6px; background: var(--border); border-radius: 3px; margin: 8px 0 16px; overflow: hidden; }
#quiz-bar { height: 100%; width: 0; background: var(--primary); transition: width .2s; }

.question { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; }
.q-meta { margin: 0 0 4px; color: var(--muted); font-size: .85rem; }
.question h3 { margin: 0 0 16px; font-size: 1.15rem; line-height: 1.4; }
#q-img { display: block; max-width: 100%; max-height: 380px; margin: 0 auto 16px; border-radius: 8px; border: 1px solid var(--border); background: #fff; }

.options { display: flex; flex-direction: column; gap: 10px; }
.option {
  display: flex; gap: 12px; align-items: flex-start; text-align: left; width: 100%;
  padding: 12px 14px; border: 1px solid var(--border); border-radius: 10px; background: var(--surface);
}
.option:hover:not(:disabled) { border-color: var(--primary); }
.option:disabled { cursor: default; }
.option .letter {
  flex: 0 0 28px; height: 28px; border-radius: 50%; display: grid; place-items: center;
  border: 1px solid var(--border); font-weight: 600; font-size: .9rem;
}
.option.correct { border-color: var(--ok); background: var(--ok-bg); }
.option.correct .letter { background: var(--ok); color: #fff; border-color: var(--ok); }
.option.wrong { border-color: var(--ko); background: var(--ko-bg); }
.option.wrong .letter { background: var(--ko); color: #fff; border-color: var(--ko); }

.feedback { margin-top: 16px; padding: 12px 14px; border-radius: 10px; }
.feedback.ok { background: var(--ok-bg); border: 1px solid var(--ok); }
.feedback.ko { background: var(--ko-bg); border: 1px solid var(--ko); }
.feedback strong { display: block; margin-bottom: 4px; }

.quiz-actions { display: flex; justify-content: space-between; gap: 10px; margin-top: 18px; flex-wrap: wrap; }
.quiz-actions.left { justify-content: flex-start; }
.primary, .ghost, .danger { padding: 10px 18px; border-radius: 10px; border: 1px solid var(--border); background: var(--surface); }
.primary { background: var(--primary); color: var(--primary-text); border-color: var(--primary); }
.danger { color: var(--ko); border-color: var(--ko); }
.file-btn { display: inline-block; cursor: pointer; }

.result-score { text-align: center; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 24px; }
.big { font-size: 3rem; font-weight: 700; }
.review { padding-left: 20px; }
.review li { margin-bottom: 12px; background: var(--surface); border: 1px solid var(--border); border-radius: 10px; padding: 10px 14px; }
.review .ans-ok { color: var(--ok); }
.review .ans-ko { color: var(--ko); }
.review small { color: var(--muted); }

.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); }
th, td { padding: 8px 12px; border-bottom: 1px solid var(--border); text-align: left; font-variant-numeric: tabular-nums; }
th { color: var(--muted); font-weight: 600; font-size: .85rem; }
.chart-wrap { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 12px; height: 280px; }
.confirm { margin-top: 12px; display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }