:root {
  --bg: var(--tg-theme-bg-color, #fff);
  --fg: var(--tg-theme-text-color, #111);
  --muted: #777;
  --accent: #2a7ae2;
  --border: #e2e2e2;
}
* { box-sizing: border-box; }
body { margin: 0; font-family: system-ui, -apple-system, Segoe UI, Roboto, sans-serif; color: var(--fg); background: var(--bg); }
.site-header { position: sticky; top: 0; background: var(--bg); border-bottom: 1px solid var(--border); z-index: 10; }
.brand-bar { height: 4px; }
.site-nav { display: flex; gap: 12px; align-items: center; padding: 10px 16px; }
.nav-link { color: var(--fg); text-decoration: none; padding: 6px 4px; }
.nav-link.active { border-bottom: 2px solid var(--accent); }
.nav-user { margin-left: auto; font-size: 14px; color: var(--muted); }
.site-main { max-width: 820px; margin: 0 auto; padding: 16px; }
.muted { color: var(--muted); }
.book-list, .lesson-list { list-style: none; padding: 0; margin: 0; }
.book-item, .lesson-item { padding: 10px 0; border-bottom: 1px solid var(--border); display: flex; gap: 10px; align-items: center; justify-content: space-between; }
.book-title, .lesson-item a { font-weight: 600; color: var(--fg); text-decoration: none; }
.badge { background: var(--accent); color: #fff; border-radius: 10px; padding: 1px 8px; font-size: 12px; }
.badge.ok { background: #2ea44f; }
.lesson-item.completed a { color: #2ea44f; }
.lesson-item.locked a { color: var(--muted); }
.reader-line { padding: 6px 0; }
.line-main { font-size: 1.05rem; }
.line-native { font-size: 0.95rem; }
.reader-nav { display: flex; gap: 12px; justify-content: space-between; margin-top: 24px; }
.exercise { border: 1px solid var(--border); border-radius: 8px; padding: 12px; margin-bottom: 12px; }
.exercise-body { line-height: 2; }
.slot { padding: 2px 6px; border: 1px solid var(--border); border-radius: 4px; min-width: 80px; }
.slot.correct { border-color: #2ea44f; background: #eaffef; }
.slot.wrong { border-color: #d33; background: #ffecec; }
.exercise-actions { display: flex; gap: 10px; align-items: center; margin-top: 8px; }
.lesson-finish { margin-top: 24px; }
.lesson-result { margin-top: 8px; font-weight: 600; }
.btn-check, .btn-finish { padding: 6px 14px; border: 1px solid var(--border); border-radius: 6px; background: var(--accent); color: #fff; cursor: pointer; }
.btn-finish { background: #2ea44f; }
.error-page { text-align: center; padding: 40px 0; }
.nav-langs { display: flex; gap: 6px; margin-left: 12px; }
.lang-link { color: var(--muted); text-decoration: none; font-size: 12px; text-transform: uppercase; }
.lang-link.active { color: var(--fg); font-weight: 600; }
.auth-box { border: 1px solid var(--border); border-radius: 8px; padding: 12px; margin: 12px 0; }
.auth-row { display: flex; gap: 8px; align-items: center; margin: 6px 0; }
.auth-row label { min-width: 120px; color: var(--muted); }
.auth-row input { flex: 1; padding: 4px 8px; border: 1px solid var(--border); border-radius: 4px; }
.auth-row button { padding: 4px 10px; cursor: pointer; }
.auth-row code { font-family: monospace; font-size: 12px; }
.hidden { display: none; }
.summary { list-style: none; padding: 0; display: flex; gap: 16px; }