:root {
  --bg: #f7f7f5;
  --surface: #ffffff;
  --text: #1c1c1a;
  --muted: #62625d;
  --line: #e2e2dc;
  --accent: #1d5fd1;
  --accent-soft: #e8f0fd;
  --ok: #17803d;
  --ok-soft: #e4f4ea;
  --bad: #b3261e;
  --bad-soft: #fbe9e7;
  --warn-soft: #fff4d6;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #131413; --surface: #1c1d1c; --text: #ecece8; --muted: #9c9c95; --line: #2f302e;
    --accent: #7aa7f5; --accent-soft: #1b2a45; --ok: #5fcf85; --ok-soft: #163322;
    --bad: #f2887f; --bad-soft: #3a1c19; --warn-soft: #3a3115; color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #131413; --surface: #1c1d1c; --text: #ecece8; --muted: #9c9c95; --line: #2f302e;
  --accent: #7aa7f5; --accent-soft: #1b2a45; --ok: #5fcf85; --ok-soft: #163322;
  --bad: #f2887f; --bad-soft: #3a1c19; --warn-soft: #3a3115; color-scheme: dark;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; padding-top: var(--hdr, 52px); background: var(--bg); color: var(--text);
  font: 16px/1.65 -apple-system, BlinkMacSystemFont, "PingFang SC", "Noto Sans SC", "Segoe UI", sans-serif;
}
.wrap { max-width: 820px; margin: 0 auto; padding: 0 16px; }
h1, h2, h3 { line-height: 1.3; margin: 0; }
h2 { font-size: 1.15rem; margin: 28px 0 12px; }
a { color: var(--accent); }

.top { border-bottom: 1px solid var(--line); background: var(--surface); position: fixed; top: env(safe-area-inset-top, 0px); left: 0; right: 0; z-index: 5; }
.top-inner { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding-top: 12px; padding-bottom: 12px; }
.top h1 { font-size: 1.1rem; }
.stats { display: flex; gap: 8px; flex-wrap: wrap; justify-content: flex-end; font-size: .82rem; color: var(--muted); }
.stats span { background: var(--accent-soft); color: var(--accent); padding: 2px 10px; border-radius: 99px; white-space: nowrap; }

.card { background: var(--surface); border: 1px solid var(--line); border-radius: 14px; padding: 18px; margin-top: 20px; }
.eyebrow { font-size: .8rem; color: var(--muted); margin-bottom: 6px; }
.card h2.title { font-size: 1.25rem; margin: 0 0 10px; }
.badges { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 12px; }
.badge { font-size: .75rem; padding: 2px 9px; border-radius: 99px; border: 1px solid var(--line); color: var(--muted); }
.badge.demo { background: var(--warn-soft); border-color: transparent; color: var(--text); }
.reason { margin: 0 0 14px; }
.actions { display: flex; gap: 10px; flex-wrap: wrap; }
button, .btn {
  font: inherit; cursor: pointer; border-radius: 10px; padding: 8px 14px; border: 1px solid var(--line);
  background: var(--surface); color: var(--text); text-decoration: none; display: inline-block;
}
button.primary, .btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
button:focus-visible, .btn:focus-visible, a:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.player { margin-top: 14px; aspect-ratio: 16 / 9; width: 100%; border: 0; border-radius: 10px; background: #000; }

.tabs { display: flex; gap: 6px; margin: 20px 0 0; overflow-x: auto; border-bottom: 1px solid var(--line); }
.tabs button { border: 0; border-bottom: 2px solid transparent; border-radius: 0; background: none; color: var(--muted); padding: 10px 12px; white-space: nowrap; }
.tabs button[aria-selected="true"] { color: var(--accent); border-bottom-color: var(--accent); }
.panel { padding: 16px 0; }
.panel ul { padding-left: 1.2em; margin: 8px 0; }
.panel li { margin: 6px 0; }
.summary { background: var(--accent-soft); border-radius: 10px; padding: 12px 14px; margin: 0 0 14px; }

.seg { padding: 10px 0; border-bottom: 1px dashed var(--line); }
.seg .t { color: var(--muted); font-size: .78rem; font-variant-numeric: tabular-nums; }
.seg .en { margin: 2px 0; }
.seg .zh { margin: 2px 0; color: var(--accent); }
.hide-zh .seg .zh { display: none; }
.toolbar { display: flex; gap: 10px; align-items: center; margin-bottom: 8px; font-size: .9rem; color: var(--muted); }

.gloss dt { font-weight: 600; margin-top: 10px; }
.gloss dd { margin: 2px 0 0; color: var(--muted); }

.q { border: 1px solid var(--line); border-radius: 12px; padding: 12px 14px; margin: 12px 0; }
.q p { margin: 0 0 8px; font-weight: 600; }
.opt { display: block; width: 100%; text-align: left; margin: 6px 0; }
.opt.right { background: var(--ok-soft); border-color: var(--ok); }
.opt.wrong { background: var(--bad-soft); border-color: var(--bad); }
.q .explain { font-weight: 400; margin: 8px 0 0; font-size: .92rem; color: var(--muted); }
.score { font-weight: 600; margin: 12px 0; }

.pending { background: var(--warn-soft); border-radius: 12px; padding: 14px 16px; margin-top: 16px; }
.pending code, .pending pre { background: var(--bg); border-radius: 6px; font-size: .85rem; }
.pending pre { padding: 8px 10px; overflow-x: auto; }
.pending ol { padding-left: 1.2em; }

.path-list { list-style: none; margin: 0; padding: 0; }
.path-list li { display: flex; gap: 10px; align-items: flex-start; padding: 10px 0; border-bottom: 1px solid var(--line); }
.path-list .n { color: var(--muted); font-variant-numeric: tabular-nums; min-width: 1.6em; }
.path-list button { border: 0; background: none; padding: 0; text-align: left; color: var(--text); font-weight: 500; }
.path-list .meta { font-size: .78rem; color: var(--muted); }
.path-list li.current { background: var(--accent-soft); margin: 0 -8px; padding: 10px 8px; border-radius: 8px; }
.dot { font-size: .75rem; padding: 1px 8px; border-radius: 99px; background: var(--line); color: var(--muted); white-space: nowrap; margin-left: auto; }
.dot.ready { background: var(--ok-soft); color: var(--ok); }
.dot.done { background: var(--ok); color: #fff; }

.foot { color: var(--muted); font-size: .8rem; padding-top: 24px; padding-bottom: 40px; }

/* video stays in view while the transcript scrolls.
   Pinning is done in JS (position: fixed under the header) so it does not depend on sticky support. */
.player-bar { background: var(--bg); padding: 10px 0; margin-top: 12px; }
.player-bar.fixed {
  position: fixed; left: 0; right: 0; margin-top: 0; padding: 10px 16px; z-index: 4;
  top: calc(env(safe-area-inset-top, 0px) + var(--hdr, 52px));
  border-bottom: 1px solid var(--line); box-shadow: 0 10px 12px -10px rgba(0, 0, 0, .35);
}
.player-inner {
  width: min(100%, 780px, calc(36vh * 16 / 9)); margin: 0 auto;
  aspect-ratio: 16 / 9; border-radius: 10px; overflow: hidden; background: #000;
}
.player-inner iframe, #player-slot { display: block; width: 100%; height: 100%; border: 0; }

.actions button[aria-pressed="true"] { background: var(--accent-soft); border-color: var(--accent); color: var(--accent); }
.seg { padding-inline: 8px; margin-inline: -8px; border-radius: 8px; transition: background-color .2s; }
.seg .t.seek {
  border: 0; background: none; padding: 2px 0; border-radius: 4px; font: inherit; font-size: .78rem;
  color: var(--accent); cursor: pointer; font-variant-numeric: tabular-nums;
}
.seg .t.seek:hover { text-decoration: underline; }
.seg.now { background: var(--accent-soft); }
.toolbar { flex-wrap: wrap; }
@media (prefers-reduced-motion: reduce) { .seg { transition: none; } }

.player-inner { position: relative; }
.player-inner iframe, #player-slot { position: relative; z-index: 1; }
.player-msg {
  position: absolute; inset: 0; z-index: 0; display: grid; place-content: center; gap: 4px; padding: 16px;
  text-align: center; color: #fff; font-size: .9rem;
}
.player-msg a { color: #9cc3ff; }
.player-msg.show { z-index: 2; background: #1b1b1b; }
.foot-ver { margin: 4px 0 0; font-size: .72rem; opacity: .8; }

/* transcript scrolls in its own box; the page and the video stay still */
.seg-scroll {
  position: relative; height: 60vh;
  overflow-y: auto; overscroll-behavior: contain; padding: 0 10px;
  border: 1px solid var(--line); border-radius: 12px; background: var(--surface);
}
.seg-scroll .seg { margin-inline: -2px; }
.seg-scroll:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }