/* Dynamic lesson page: reuses the study/player/drawer styles from styles.css. */
.lesson-page { background: radial-gradient(900px 480px at 82% -8%, rgba(221,96,58,.08), transparent 60%), var(--paper); }
.lesson-topbar {
  position: sticky;
  top: 0;
  z-index: 65;
  border-bottom: 1px solid rgba(214,201,180,.68);
  background: rgba(245,239,227,.88);
  backdrop-filter: blur(18px) saturate(1.15);
}
.lesson-topbar-inner {
  max-width: var(--max);
  height: 68px;
  margin: 0 auto;
  padding: 0 40px;
  display: flex;
  align-items: center;
  gap: 20px;
}
.lesson-back {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--ink-soft);
  font-size: 11.5px;
  white-space: nowrap;
}
.lesson-back:hover { color: var(--accent-deep); }
.lesson-back .ic { width: 15px; height: 15px; }
.lesson-topbar .brand { margin-left: 4px; }
.lesson-top-actions { margin-left: auto; display: flex; align-items: center; gap: 10px; }
.lesson-level-pill {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 27px;
  padding: 0 9px;
  border-radius: 6px;
  background: var(--accent-soft);
  color: var(--accent-deep);
  font-family: var(--mono);
  font-size: 9px;
  font-weight: 600;
}
.lesson-shell { max-width: var(--max); margin: 0 auto; padding: 0 40px 82px; }
.lesson-head {
  display: grid;
  grid-template-columns: minmax(0, 1.25fr) minmax(300px, .75fr);
  gap: 48px;
  align-items: end;
  padding: 31px 0 30px;
}
.lesson-breadcrumb { display: flex; align-items: center; gap: 7px; color: var(--muted); font-size: 9.5px; letter-spacing: .05em; }
.lesson-breadcrumb a { color: var(--muted); }
.lesson-breadcrumb a:hover { color: var(--accent-deep); }
.lesson-breadcrumb span:nth-child(2n) { color: var(--line-strong); }
.lesson-head h1 {
  max-width: 900px;
  margin-top: 10px;
  font-size: clamp(30px, 3.3vw, 45px);
  line-height: 1.15;
  letter-spacing: -.035em;
  font-weight: 500;
  text-wrap: balance;
}
.lesson-title-zh { margin-top: 7px; color: var(--muted); font-size: 13px; line-height: 1.6; }
.lesson-meta-line { display: flex; align-items: center; gap: 9px; flex-wrap: wrap; margin-top: 14px; color: var(--muted); font-size: 10px; }
.lesson-meta-line b { color: var(--ink-soft); font-weight: 600; }
.lesson-meta-line .ic { width: 12px; height: 12px; vertical-align: -2px; margin-right: 3px; }
.lesson-meta-line .dot { width: 3px; height: 3px; border-radius: 50%; background: var(--line-strong); }
.lesson-head-side { display: flex; gap: 11px; align-items: stretch; }
.lesson-level-card {
  flex: 0 0 135px;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: 15px;
  background: var(--surface);
}
.lesson-level-card strong { display: block; margin-top: 7px; font-family: var(--serif); font-size: 45px; font-weight: 400; line-height: .9; color: var(--accent); }
.lesson-level-card > span:last-child { display: block; margin-top: 7px; color: var(--muted); font-size: 9px; line-height: 1.45; }
.lesson-progress-card { flex: 1; min-width: 150px; padding: 16px; border: 1px solid var(--line); border-radius: 15px; background: var(--surface-2); }
.lesson-progress-card > div:first-child { display: flex; justify-content: space-between; align-items: baseline; color: var(--muted); font-size: 9.5px; }
.lesson-progress-card > div:first-child b { color: var(--ink); font-size: 18px; font-weight: 500; letter-spacing: -.03em; }
.lesson-progress-bar { height: 5px; margin-top: 10px; border-radius: 99px; background: var(--surface-3); overflow: hidden; }
.lesson-progress-bar i { display: block; height: 100%; width: 0; background: var(--green); border-radius: inherit; transition: width .5s ease; }
.lesson-progress-card > span { display: block; margin-top: 9px; color: var(--muted); font-size: 9px; line-height: 1.55; }
.lesson-study { padding-top: 0; scroll-margin-top: 84px; }
.lesson-study .study-heading { margin-bottom: 18px; }
.lesson-study .study-heading h2 { font-size: clamp(25px, 2.6vw, 34px); }
.lesson-page .transcript-card { top: 84px; height: min(818px, calc(100vh - 104px)); }
.lesson-page .practice-card { border-radius: 24px; }
.lesson-page .video-card { border-radius: 24px; }
.lesson-page .video-caption { bottom: 16px; max-height: 98px; overflow: hidden; }
.lesson-page .cap-en {
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  font-size: clamp(13px, 1.25vw, 17px);
}
.cap-zh {
  max-width: 100%;
  margin-top: 4px;
  padding: 3px 10px;
  border-radius: 6px;
  background: rgba(19,18,14,.62);
  color: rgba(255,255,255,.84);
  font-size: clamp(10px, .92vw, 12px);
  line-height: 1.4;
  text-align: center;
  text-shadow: 0 1px 4px rgba(0,0,0,.45);
  backdrop-filter: blur(8px);
  display: -webkit-box;
  -webkit-line-clamp: 1;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.video-caption { flex-direction: column; align-items: center; }
.lesson-page .practice-line { font-size: clamp(22px, 2.1vw, 28px); }
.lesson-page .practice-line .tk[data-word="1"] { cursor: pointer; }
.lesson-page .tk[data-word="1"]:hover { color: var(--accent-deep); }
.lesson-page .tk.speaking { background: var(--accent) !important; color: #fff8ec !important; border-radius: 3px; }
.hl {
  background: linear-gradient(transparent 55%, var(--orange-mark) 55%);
  border-radius: 2px;
  cursor: pointer;
  box-shadow: inset 0 -1px 0 rgba(196,87,47,.16);
  transition: background .18s ease;
}
.hl:hover { background: linear-gradient(transparent 45%, #f3b183 45%); }
.blank {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 24px;
  margin: 2px 2px;
  padding: 1px 8px;
  border: 1px dashed #d28e6e;
  border-bottom: 2px solid var(--accent);
  border-radius: 5px;
  background: #fff5e7;
  color: var(--accent-deep);
  font-size: .76em;
  letter-spacing: .08em;
  font-weight: 600;
  cursor: pointer;
  vertical-align: baseline;
}
.blank:hover { background: #ffe8d5; }

/* key words */
.key-words-section { padding: 44px 0 0; scroll-margin-top: 90px; }
.key-words-head { display: flex; align-items: flex-end; justify-content: space-between; gap: 16px; margin-bottom: 15px; }
.key-words-head h2 { margin-top: 5px; font-size: 26px; font-weight: 500; letter-spacing: -.03em; }
.key-words-head > span { color: var(--muted); font-size: 9.5px; }
.key-words-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 9px; }
.kw-card {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  min-height: 103px;
  padding: 13px 14px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface);
  text-align: left;
  cursor: pointer;
  transition: border-color .18s ease, background .18s ease, transform .18s ease;
}
.kw-card:hover { border-color: var(--line-strong); background: var(--surface-2); transform: translateY(-2px); }
.kw-word { font-size: 17px; font-weight: 600; letter-spacing: -.025em; }
.kw-ipa { margin-top: 3px; font-family: var(--mono); font-size: 8px; color: var(--muted); }
.kw-zh { margin-top: 6px; color: var(--ink-soft); font-size: 10px; line-height: 1.45; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.kw-speak { position: absolute; right: 9px; top: 10px; width: 21px; height: 21px; display: grid; place-items: center; border: 0; border-radius: 50%; background: transparent; color: var(--muted); }
.kw-speak:hover { background: var(--surface-3); color: var(--ink); }
.kw-speak .ic { width: 11px; height: 11px; }
.lesson-next { margin-top: 44px; padding-top: 20px; border-top: 1px solid var(--line); display: flex; align-items: center; justify-content: space-between; gap: 18px; }
.lesson-next-label { color: var(--muted); font-size: 9.5px; }
.lesson-next a { display: flex; align-items: center; gap: 9px; margin-top: 5px; color: var(--ink-soft); font-size: 13px; font-weight: 500; }
.lesson-next a:hover { color: var(--accent-deep); }
.lesson-next-thumb { width: 74px; height: 46px; overflow: hidden; border-radius: 7px; }
.lesson-next-thumb img { width: 100%; height: 100%; object-fit: cover; }
.lesson-next .btn { flex: 0 0 auto; }
.lesson-loading { padding: 60px 20px; text-align: center; color: var(--muted); font-size: 12px; }
.lesson-loading[hidden] { display: none; }
.lesson-error {
  max-width: 620px;
  margin: 36px 0 80px;
  padding: 28px 30px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--surface);
  box-shadow: var(--shadow-sm);
}
.lesson-error h2 { margin-top: 9px; font-size: 25px; font-weight: 500; letter-spacing: -.03em; }
.lesson-error p { margin-top: 8px; color: var(--muted); font-size: 12px; line-height: 1.7; }
.lesson-error .btn { margin-top: 18px; }
.popover-word { font-size: 25px; }
.popover-ipa { font-size: 10.5px; font-family: "Segoe UI", "Lucida Sans Unicode", "Arial Unicode MS", sans-serif; letter-spacing: .015em; }
.popover-zh { font-size: 12.5px; }
.popover-note { font-size: 10px; }
.popover-example { font-size: 12.5px; }

@media (max-width: 1100px) {
  .lesson-head { grid-template-columns: 1fr; gap: 22px; align-items: start; }
  .lesson-head-side { max-width: 460px; }
  .lesson-page .transcript-card { position: static; height: 72vh; min-height: 540px; }
  .key-words-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}
@media (max-width: 820px) {
  .lesson-topbar-inner { height: 62px; padding: 0 20px; gap: 10px; }
  .lesson-topbar .brand-copy small { display: none; }
  .lesson-back span { display: none; }
  .lesson-top-actions .nav-bookmark span { display: none; }
  .lesson-top-actions .nav-bookmark { padding: 0 9px; }
  .lesson-shell { padding-left: 20px; padding-right: 20px; }
  .lesson-head { padding: 24px 0 22px; }
  .lesson-head h1 { font-size: clamp(27px, 6.8vw, 35px); }
  .lesson-meta-line { gap: 7px; font-size: 9px; }
  .lesson-level-card { flex: 0 0 110px; padding: 13px; }
  .lesson-level-card strong { font-size: 36px; }
  .lesson-progress-card { padding: 13px; }
  .lesson-study .study-heading { margin-bottom: 14px; }
  .lesson-page .transcript-card { height: 73vh; min-height: 500px; }
  .key-words-section { padding-top: 38px; }
  .key-words-head h2 { font-size: 23px; }
  .key-words-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .lesson-next { flex-direction: column; align-items: flex-start; }
  .lesson-next .btn { width: 100%; }
  .lesson-page .video-caption { bottom: 11px; }
  .lesson-page .cap-en { font-size: 12px; }
  .cap-zh { font-size: 9.5px; }
}
@media (max-width: 520px) {
  .lesson-head-side { display: block; }
  .lesson-level-card { display: inline-flex; gap: 8px; align-items: baseline; flex: none; width: 100%; margin-bottom: 8px; }
  .lesson-level-card strong { margin: 0; font-size: 30px; }
  .lesson-level-card > span:last-child { margin: 0; }
  .lesson-page .practice-line { font-size: 21px; }
  .key-words-grid { grid-template-columns: 1fr 1fr; gap: 7px; }
  .kw-card { min-height: 96px; padding: 11px; }
  .kw-word { font-size: 15px; }
}