:root {
  --bg: #f4f6fa; --surface: #fff; --text: #1b1f27; --muted: #6b7280; --border: #e3e7ee;
  --primary: #0063f0; --primary-soft: #e6f0ff; --good: #12a150; --good-soft: #e5f6ec; --bad: #e0393e; --bad-soft: #fdeaea;
}
[data-theme="dark"] {
  --bg: #0f1218; --surface: #1a1f29; --text: #e8ebf1; --muted: #9aa3b2; --border: #2a3140;
  --primary: #4d8dff; --primary-soft: #1c2a45; --good: #3ccf7e; --good-soft: #15301f; --bad: #ff6b6f; --bad-soft: #3a1c1e;
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--text); font: 16px/1.55 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; }
a { color: var(--primary); text-decoration: none; }
h1 { font-size: 1.6rem; margin: .4rem 0 1rem; }
h2 { font-size: 1.2rem; }
.wrap { max-width: 760px; margin: 0 auto; padding: 0 16px; }
main { padding-bottom: 48px; }

header { background: var(--surface); border-bottom: 1px solid var(--border); position: sticky; top: 0; z-index: 10; }
header .wrap { display: flex; align-items: center; gap: 16px; height: 56px; }
.brand { display: flex; align-items: center; gap: 8px; font-weight: 700; color: var(--text); }
.brand img { width: 28px; height: 28px; border-radius: 7px; }
nav { display: flex; gap: 4px; margin-left: auto; }
nav a { padding: 6px 12px; border-radius: 8px; color: var(--muted); font-weight: 600; }
nav a.active { background: var(--primary-soft); color: var(--primary); }
.theme { border: 0; background: none; color: var(--text); font-size: 1.2rem; cursor: pointer; }
@media (max-width: 520px) { .brand { font-size: 0; gap: 0; } nav a { padding: 6px 8px; } }

.back { display: inline-block; margin-top: 16px; font-weight: 600; }
.muted { color: var(--muted); font-size: .9rem; }
.center { text-align: center; justify-content: center; }
.grow { flex: 1; min-width: 0; }

.card { display: flex; align-items: center; gap: 14px; background: var(--surface); border: 1px solid var(--border);
  border-radius: 12px; padding: 14px 16px; margin-bottom: 10px; color: var(--text); }
a.card:hover { border-color: var(--primary); }
.card .title { font-weight: 600; }
.card .icon { width: 52px; height: 52px; }
.num { width: 32px; height: 32px; border-radius: 50%; display: grid; place-items: center; background: var(--primary-soft);
  color: var(--primary); font-weight: 700; flex: none; }
.num.done { background: var(--good); color: #fff; }
.bar { height: 6px; background: var(--border); border-radius: 3px; overflow: hidden; margin: 6px 0 4px; }
.bar span { display: block; height: 100%; background: var(--primary); }
.badge { font-size: .8rem; font-weight: 700; padding: 3px 10px; border-radius: 99px; }
.badge.pass, .score.pass { background: var(--good-soft); color: var(--good); }
.badge.fail, .score.fail { background: var(--bad-soft); color: var(--bad); }

.btn { display: inline-block; border: 1px solid var(--border); background: var(--surface); color: var(--text); font: inherit;
  font-weight: 600; padding: 10px 18px; border-radius: 10px; cursor: pointer; }
.btn:hover:not(:disabled) { border-color: var(--primary); }
.btn.primary { background: var(--primary); border-color: var(--primary); color: #fff; }
.btn:disabled { opacity: .45; cursor: default; }
.btn.link { border: 0; background: none; color: var(--muted); font-weight: 400; padding: 0; text-decoration: underline; }
.actions { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin: 20px 0; }

.lesson { background: var(--surface); border: 1px solid var(--border); border-radius: 12px; padding: 8px 22px 18px; }
.lesson h3 { margin: 1.2em 0 .3em; }
.lesson figure { margin: 18px 0; text-align: center; }
.lesson figure img { display: block; max-width: 100%; max-height: 420px; margin: 0 auto; border-radius: 8px; }
.lesson figcaption { margin-top: 6px; font-size: .9rem; color: var(--muted); }
.lesson ul { padding-left: 1.3em; }

.runbar { display: flex; align-items: center; gap: 12px; margin: 16px 0 10px; }
.runbar .back { margin: 0; }
.runbar .title { flex: 1; font-weight: 600; text-align: center; }
.timer { font-variant-numeric: tabular-nums; font-weight: 700; padding: 3px 10px; border-radius: 8px; background: var(--primary-soft); color: var(--primary); }
.timer.low { background: var(--bad-soft); color: var(--bad); }
.dots { display: flex; flex-wrap: wrap; gap: 6px; margin: 8px 0 14px; }
.dot { width: 32px; height: 32px; border-radius: 8px; border: 1px solid var(--border); background: var(--surface); color: var(--muted);
  font: inherit; font-size: .8rem; cursor: pointer; }
.dot.answered { background: var(--primary-soft); color: var(--primary); border-color: transparent; }
.dot.current { border: 2px solid var(--primary); color: var(--text); }
.question { font-size: 1.25rem; margin: 6px 0 18px; }
.options { display: grid; gap: 10px; }
.option { text-align: left; font: inherit; color: var(--text); background: var(--surface); border: 2px solid var(--border);
  border-radius: 12px; padding: 14px 16px; cursor: pointer; }
.option:hover:not(:disabled) { border-color: var(--primary); }
.option.selected { border-color: var(--primary); background: var(--primary-soft); }
.option.correct { border-color: var(--good); background: var(--good-soft); }
.option.wrong { border-color: var(--bad); background: var(--bad-soft); }
.option:disabled { cursor: default; color: var(--text); }
.feedback { margin-top: 16px; padding: 14px 16px; border-radius: 12px; }
.feedback.good { background: var(--good-soft); }
.feedback.bad { background: var(--bad-soft); }

.score { display: inline-block; font-size: 2rem; font-weight: 800; padding: 10px 22px; border-radius: 14px; }
.score small { font-size: 1rem; font-weight: 600; margin-left: 6px; }
.review { display: block; }
.review .q { font-weight: 600; margin-bottom: 6px; }
.review .yours.good { color: var(--good); }
.review .yours.bad { color: var(--bad); }
.review p { margin: 4px 0; }

.flash { background: var(--surface); border: 1px solid var(--border); border-radius: 16px; min-height: 260px; padding: 28px;
  display: flex; flex-direction: column; justify-content: center; align-items: center; text-align: center; cursor: pointer; user-select: none; }
.flash.flipped { background: var(--primary-soft); }
.flash .word { font-size: 2rem; font-weight: 800; }
.flash .def { font-size: 1.2rem; font-weight: 600; }
.flash .example { margin-top: 14px; color: var(--muted); font-style: italic; }
.flash .hint { margin-top: 22px; font-size: .8rem; color: var(--muted); }
.toolbar { display: flex; align-items: center; gap: 14px; margin-bottom: 14px; flex-wrap: wrap; }