:root {
  --bg: #f8fafc;
  --card: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --border: #e2e8f0;
  --accent: #1d4ed8;
  --accent-text: #ffffff;
  --good: #15803d;
  --good-bg: #dcfce7;
  --bad: #b91c1c;
  --bad-bg: #fee2e2;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b1120;
    --card: #111827;
    --text: #e5e7eb;
    --muted: #94a3b8;
    --border: #1f2937;
    --accent: #3b82f6;
    --good: #4ade80;
    --good-bg: #052e16;
    --bad: #f87171;
    --bad-bg: #450a0a;
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  font: 17px/1.45 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  -webkit-text-size-adjust: 100%;
  padding-bottom: env(safe-area-inset-bottom);
}

.topbar {
  position: sticky; top: 0; z-index: 10;
  display: flex; align-items: center; gap: 8px;
  padding: calc(env(safe-area-inset-top) + 8px) 12px 8px;
  background: var(--card);
  border-bottom: 1px solid var(--border);
}
.topbar h1 { flex: 1; font-size: 18px; margin: 0; }
.nav { background: none; border: 0; font-size: 22px; padding: 4px 6px; cursor: pointer; }
.lang-btn { display: inline-flex; align-items: center; }
.flag { display: inline-block; width: 27px; height: 18px; border-radius: 3px; overflow: hidden; flex: none;
  box-shadow: 0 0 0 1px rgba(0, 0, 0, .15); }
.flag svg { display: block; width: 100%; height: 100%; }
.lang-menu { position: absolute; top: 100%; right: 12px; z-index: 20; min-width: 220px; padding: 6px;
  background: var(--card); border: 1px solid var(--border); border-radius: 12px; box-shadow: 0 8px 24px rgba(0, 0, 0, .18); }
.lang-menu button { display: flex; align-items: center; gap: 12px; width: 100%; padding: 12px 10px; min-height: 48px;
  font: inherit; color: var(--text); background: none; border: 0; border-radius: 8px; text-align: left; cursor: pointer; }
.lang-menu button:hover, .lang-menu button:focus-visible { background: var(--bg); outline: none; }
.lang-menu .name { flex: 1; }
.lang-menu .check { color: var(--accent); font-weight: 700; }
.sync-dot { width: 10px; height: 10px; border-radius: 50%; background: var(--border); }
.sync-dot.ok { background: var(--good); }
.sync-dot.busy { background: #eab308; }
.sync-dot.err { background: var(--bad); }

main { max-width: 760px; margin: 0 auto; padding: 16px; }

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 16px;
  margin-bottom: 14px;
}
.card h2 { margin: 0 0 10px; font-size: 18px; }
.muted { color: var(--muted); font-size: 14px; }

.stats-row { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; text-align: center; }
.stats-row b { display: block; font-size: 22px; }
.stats-row span { color: var(--muted); font-size: 12px; }

.progress { height: 8px; background: var(--border); border-radius: 4px; overflow: hidden; margin-top: 12px; }
.progress > div { height: 100%; background: var(--accent); }

.modes { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
@media (min-width: 600px) { .modes { grid-template-columns: repeat(3, 1fr); } }

button.btn, .modes button {
  font: inherit;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  border-radius: 12px;
  padding: 14px 12px;
  text-align: left;
  cursor: pointer;
  min-height: 48px;
}
.modes button b { display: block; }
.modes button small { color: var(--muted); }
button.primary { background: var(--accent); color: var(--accent-text); border-color: var(--accent); text-align: center; }
button:disabled { opacity: .5; }

select, input[type=text], input[type=password] {
  font: inherit; width: 100%;
  padding: 10px; border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--bg); color: var(--text);
}
.sync-code { font-family: ui-monospace, Menlo, monospace; font-size: 28px; font-weight: 700; letter-spacing: 2px; text-align: center; padding: 12px; margin: 8px 0; border: 2px dashed var(--border); border-radius: 12px; user-select: all; -webkit-user-select: all; }
.mono { font-family: ui-monospace, Menlo, monospace; font-size: 13px; }
label { display: block; margin: 10px 0 4px; font-size: 14px; color: var(--muted); }
label.first { margin-top: 0; }

.qmeta { display: flex; justify-content: space-between; color: var(--muted); font-size: 14px; margin-bottom: 8px; align-items: center; gap: 8px; }
.lang-toggle { display: inline-flex; border: 1px solid var(--border); border-radius: 999px; overflow: hidden; }
.lang-toggle button { font: inherit; font-size: 14px; border: 0; background: none; color: var(--muted); padding: 4px 12px; min-height: 32px; cursor: pointer; }
.lang-toggle button.on { background: var(--accent); color: var(--accent-text); }
.lang-toggle button:disabled { opacity: .35; cursor: default; }
.qtext { font-size: 19px; margin: 0 0 14px; white-space: pre-wrap; }
.qimg { display: inline-block; max-width: 100%; max-height: 200px; margin: 0 6px 14px 0; border-radius: 8px; background: #fff; }

.options { display: grid; gap: 10px; }
.options.pics { grid-template-columns: repeat(3, 1fr); }
.options.pics button { text-align: center; }
.options button {
  font: inherit; text-align: left;
  padding: 14px; min-height: 52px;
  border-radius: 12px;
  border: 2px solid var(--border);
  background: var(--card); color: var(--text);
  cursor: pointer;
}
.optimg { display: block; max-width: 100%; height: 72px; object-fit: contain; margin: 6px auto 0; }
.thumb { float: right; height: 44px; margin: 0 0 4px 8px; }
.options button:disabled { opacity: 1; }
.options button:disabled:not(.correct):not(.wrong) { color: var(--muted); }
.options button.correct { border-color: var(--good); background: var(--good-bg); }
.options button.wrong { border-color: var(--bad); background: var(--bad-bg); }

.feedback { margin-top: 14px; font-weight: 600; }
.feedback.good { color: var(--good); }
.feedback.bad { color: var(--bad); }
.actions { display: flex; gap: 10px; margin-top: 14px; }
.actions button { flex: 1; text-align: center; }

table.weak { width: 100%; border-collapse: collapse; font-size: 14px; }
table.weak td { padding: 8px 4px; border-top: 1px solid var(--border); vertical-align: top; }
table.weak td.num { text-align: right; white-space: nowrap; color: var(--bad); }

table.editions { width: 100%; border-collapse: collapse; font-size: 15px; margin-bottom: 8px; }
table.editions th, table.editions td { padding: 8px 4px; border-top: 1px solid var(--border); text-align: left; vertical-align: top; }
table.editions th { white-space: nowrap; padding-right: 12px; }
table.editions td.muted { text-align: right; white-space: nowrap; }
a { color: var(--accent); }
a.link-btn { display: block; text-align: center; text-decoration: none; color: var(--text); border: 1px solid var(--border); border-radius: 12px; padding: 14px 12px; }

.result-score { font-size: 48px; font-weight: 700; text-align: center; margin: 8px 0; }
.pass { color: var(--good); }
.fail { color: var(--bad); }