:root {
  --brand: #6b45b8;
  --brand-soft: #efe9fa;
  --bg: var(--tg-theme-bg-color, #ffffff);
  --bg2: var(--tg-theme-secondary-bg-color, #f4f2f8);
  --text: var(--tg-theme-text-color, #1d1a24);
  --hint: var(--tg-theme-hint-color, #8a8496);
  --link: var(--tg-theme-link-color, #6b45b8);
  --btn: var(--tg-theme-button-color, #6b45b8);
  --btn-text: var(--tg-theme-button-text-color, #ffffff);
  --ok: #2e9d5b;
  --bad: #d1435b;
  --radius: 14px;
}
@media (prefers-color-scheme: dark) {
  :root:not(.tg) {
    --bg: #17151c; --bg2: #221f2a; --text: #ece9f2; --hint: #9a94a6;
    --link: #b49aec; --brand-soft: #2f2740;
  }
}
* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  background: var(--bg2); color: var(--text);
  font: 16px/1.5 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  padding-bottom: 88px;
}
.topbar {
  position: sticky; top: 0; z-index: 5; display: flex; align-items: center; gap: 8px;
  padding: 12px 16px; background: var(--bg); border-bottom: 1px solid color-mix(in srgb, var(--hint) 20%, transparent);
}
.tg .topbar { display: none; }
.brand { font-weight: 700; letter-spacing: .02em; color: var(--brand); }
.brand span { font-weight: 400; color: var(--hint); }
.back { border: 0; background: none; font-size: 28px; line-height: 1; color: var(--link); padding: 0 6px 2px 0; cursor: pointer; }
main { max-width: 680px; margin: 0 auto; padding: 16px; }
h1 { font-size: 22px; line-height: 1.25; margin: 4px 0 6px; }
h2 { font-size: 13px; text-transform: uppercase; letter-spacing: .06em; color: var(--hint); margin: 22px 4px 8px; font-weight: 600; }
.sub { color: var(--hint); font-size: 14px; margin: 0 0 12px; }
.card { background: var(--bg); border-radius: var(--radius); padding: 14px 16px; }
.list { display: grid; gap: 8px; }
.row {
  display: flex; align-items: center; gap: 12px; width: 100%; text-align: left;
  background: var(--bg); color: inherit; border: 0; border-radius: var(--radius);
  padding: 12px 14px; font: inherit; cursor: pointer;
}
.row:disabled { cursor: default; opacity: .55; }
.row .t { flex: 1; min-width: 0; }
.row .t b { display: block; font-weight: 600; overflow-wrap: anywhere; }
.row .t small { color: var(--hint); font-size: 13px; }
.icon {
  flex: none; width: 34px; height: 34px; border-radius: 10px; display: grid; place-items: center;
  background: var(--brand-soft); color: var(--brand); font-size: 16px; font-weight: 700;
}
.icon.done { background: color-mix(in srgb, var(--ok) 16%, transparent); color: var(--ok); }
.icon.lock { background: var(--bg2); color: var(--hint); }
.bar { height: 6px; border-radius: 3px; background: var(--bg2); overflow: hidden; margin-top: 6px; }
.bar i { display: block; height: 100%; background: var(--brand); border-radius: 3px; }
.tabs { display: flex; gap: 6px; background: var(--bg); padding: 4px; border-radius: 12px; margin-bottom: 4px; }
.tabs button {
  flex: 1; border: 0; background: none; color: var(--hint); font: inherit; font-size: 14px;
  padding: 8px; border-radius: 9px; cursor: pointer;
}
.tabs button[aria-pressed="true"] { background: var(--brand-soft); color: var(--brand); font-weight: 600; }
.note { font-size: 12px; color: var(--hint); margin: 6px 4px 0; }

/* lesson content */
.content { background: var(--bg); border-radius: var(--radius); padding: 18px 16px; overflow-wrap: anywhere; }
.content p { margin: 0 0 12px; }
.content h3 { font-size: 19px; margin: 20px 0 8px; line-height: 1.3; }
.content h4 { font-size: 17px; margin: 16px 0 6px; }
.content ul, .content ol { padding-left: 22px; margin: 0 0 12px; }
.content li p { margin: 0 0 4px; }
.content a { color: var(--link); }
.content hr, .divider { border: 0; height: 1px; background: color-mix(in srgb, var(--hint) 25%, transparent); margin: 18px 0; }
.gallery { display: flex; gap: 8px; overflow-x: auto; scroll-snap-type: x mandatory; margin: 6px -16px 14px; padding: 0 16px; }
.gallery img { scroll-snap-align: center; border-radius: 10px; max-height: 70vh; width: auto; max-width: 100%; flex: none; background: var(--bg2); }
.gallery.many img { max-width: 86%; }
video { width: 100%; border-radius: 10px; margin: 6px 0 14px; background: #000; }
.chip {
  display: inline-flex; align-items: center; gap: 8px; text-decoration: none; color: var(--link);
  background: var(--brand-soft); padding: 10px 14px; border-radius: 10px; margin: 0 0 12px; font-weight: 600;
}
.task { border: 1.5px dashed color-mix(in srgb, var(--brand) 45%, transparent); border-radius: 12px; padding: 12px; margin: 10px 0 14px; }
.task b { display: block; margin-bottom: 6px; }
.task textarea {
  width: 100%; min-height: 90px; border-radius: 10px; border: 1px solid color-mix(in srgb, var(--hint) 35%, transparent);
  background: var(--bg2); color: var(--text); font: inherit; padding: 10px; resize: vertical;
}
.task .sent { color: var(--ok); font-size: 14px; margin-top: 6px; }
.small-btn {
  border: 0; background: var(--btn); color: var(--btn-text); border-radius: 10px; padding: 9px 14px;
  font: inherit; font-weight: 600; margin-top: 8px; cursor: pointer;
}

/* test */
.q { font-size: 18px; font-weight: 600; margin: 4px 0 14px; line-height: 1.35; }
.opt {
  display: flex; gap: 10px; align-items: flex-start; width: 100%; text-align: left; font: inherit; color: inherit;
  background: var(--bg); border: 2px solid transparent; border-radius: 12px; padding: 12px 14px; margin-bottom: 8px; cursor: pointer;
}
.opt .mark { flex: none; width: 22px; height: 22px; border-radius: 50%; border: 2px solid var(--hint); margin-top: 1px; }
.opt.multi .mark { border-radius: 6px; }
.opt[aria-pressed="true"] { border-color: var(--brand); }
.opt[aria-pressed="true"] .mark { border-color: var(--brand); background: var(--brand); box-shadow: inset 0 0 0 3px var(--bg); }
.opt.right { border-color: var(--ok); background: color-mix(in srgb, var(--ok) 10%, var(--bg)); }
.opt.wrong { border-color: var(--bad); background: color-mix(in srgb, var(--bad) 10%, var(--bg)); }
.opt:disabled { cursor: default; }
.expl { font-size: 14px; color: var(--hint); margin: -2px 4px 10px; }
.progress-dots { display: flex; gap: 4px; margin: 0 0 14px; }
.progress-dots i { flex: 1; height: 4px; border-radius: 2px; background: color-mix(in srgb, var(--hint) 25%, transparent); }
.progress-dots i.on { background: var(--brand); }
.result { text-align: center; padding: 26px 16px; }
.result .big { font-size: 44px; font-weight: 800; margin: 6px 0; }
.result.pass .big { color: var(--ok); }
.result.fail .big { color: var(--bad); }

.bottom {
  position: fixed; left: 0; right: 0; bottom: 0; padding: 12px 16px calc(12px + env(safe-area-inset-bottom));
  background: linear-gradient(to top, var(--bg2) 70%, transparent);
}
.primary {
  display: block; width: 100%; max-width: 648px; margin: 0 auto; border: 0; border-radius: 12px;
  background: var(--btn); color: var(--btn-text); font: inherit; font-weight: 700; padding: 14px; cursor: pointer;
}
.primary:disabled { opacity: .45; cursor: default; }
.tg .bottom { display: none; }
.empty { text-align: center; color: var(--hint); padding: 40px 16px; }