/**
 * L13 互动课页面外壳 —— 全屏舞台 + 统一底栏导航
 * 各页在 :root 中设置 --l13-accent / --l13-accent-ink / --l13-top-bg 等主题色
 */
:root {
  --lesson-pager-gap: 2.35rem;
}

body.has-lesson-pager {
  align-items: stretch !important;
  justify-content: flex-start;
}

body.has-lesson-pager > #app {
  width: 100% !important;
  max-width: 100% !important;
  margin-left: 0 !important;
  margin-right: 0 !important;
  padding: 4px 6px !important;
  padding-left: max(4px, var(--lesson-s-l, 0px)) !important;
  padding-right: max(4px, var(--lesson-s-r, 0px)) !important;
}

@media (min-width: 769px) and (min-height: 560px) {
  body.has-lesson-pager > #app {
    --l13-stage-vw: calc(100vw - var(--lesson-s-l) - var(--lesson-s-r) - 12px);
    --l13-stage-vh: calc(
      100dvh - var(--lesson-pager-gap, 2.35rem) - max(2px, var(--lesson-s-t)) - max(2px, var(--lesson-s-b)) - 8px
    );
    width: var(--l13-stage-vw) !important;
    max-width: var(--l13-stage-vw) !important;
    height: var(--l13-stage-vh) !important;
    max-height: var(--l13-stage-vh) !important;
    aspect-ratio: unset !important;
    flex: 1 1 auto !important;
  }
}

#ui-lock {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 9998;
  cursor: wait;
  background: rgba(15, 23, 42, 0.08);
}
#ui-lock.active { display: block; }

#app {
  flex: 1 1 auto;
  width: 100%;
  max-width: 100%;
  margin: 0;
  display: flex;
  flex-direction: column;
  min-height: calc(100dvh - var(--lesson-pager-gap, 2.35rem) - 4px);
  min-width: 0;
}

#l13-book.book {
  position: relative;
  flex: 1 1 auto;
  min-height: 0;
  display: flex;
  flex-direction: column;
  background: var(--paper, #fff9f0);
  border: 3px solid var(--l13-accent, #0d9488);
  border-radius: 12px 22px 14px 20px;
  box-shadow:
    0 6px 0 var(--l13-shadow, rgba(13, 148, 136, 0.32)),
    0 18px 36px var(--shadow-book, rgba(60, 40, 20, 0.12));
  overflow: hidden;
}

#l13-book.book::before {
  content: "";
  position: absolute;
  inset: 8px;
  border: 2px dashed var(--l13-dash, rgba(13, 148, 136, 0.3));
  border-radius: 8px 16px 10px 14px;
  pointer-events: none;
  z-index: 0;
}

#l13-book .top-bar {
  z-index: 2;
  flex-shrink: 0;
  margin: 8px 10px 0;
  padding: 8px 12px;
  border: 2px solid var(--l13-accent, #0d9488);
  border-radius: 14px;
  background: var(--l13-top-bg, linear-gradient(180deg, #fff, #f0fdfa));
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 0.35rem 0.75rem;
  text-align: center;
  font-size: clamp(0.82rem, 0.35vw + 0.76rem, 0.96rem);
}

#l13-book .top-bar .top-bar-main {
  flex: 1 1 auto;
  min-width: 0;
}

#l13-book .top-bar strong {
  color: var(--l13-accent-ink, #0f766e);
  font-size: clamp(0.95rem, 1vw + 0.8rem, 1.08rem);
}

#l13-book .subtitle-line {
  display: block;
  margin-top: 2px;
  font-size: 0.8em;
  color: #6d4c41;
  font-weight: 600;
  line-height: 1.35;
}

.l13-scroll {
  position: relative;
  z-index: 1;
  flex: 1 1 auto;
  min-height: 0;
  overflow: hidden;
  padding: 6px 10px 8px;
  display: flex;
  flex-direction: column;
}

.l13-scroll > .lesson-page {
  display: none;
  flex-direction: column;
  gap: 0.5rem;
  flex: 1 1 auto;
  min-height: 0;
  animation: l13fade 0.3s ease;
}

.l13-scroll > .lesson-page.active {
  display: flex;
}

.l13-scroll > .lesson-page.active > .panel,
.l13-scroll > .lesson-page.active > .panel.panel-split {
  flex: 1 1 auto;
  min-height: 0;
  display: flex;
  flex-direction: column;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
}

@keyframes l13fade {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: none; }
}

#l13-book .page-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.35rem 0.75rem;
  padding-bottom: 0.35rem;
  border-bottom: 2px solid rgba(93, 64, 55, 0.12);
  flex-shrink: 0;
}

#l13-book .page-kicker {
  font-size: 0.76rem;
  font-weight: 800;
  color: #6d4c41;
  letter-spacing: 0.04em;
}

#l13-book .page-title {
  margin: 0;
  font-size: clamp(1.02rem, 1.6vw + 0.5rem, 1.28rem);
  font-weight: 900;
  color: var(--l13-accent-ink, #0f766e);
  line-height: 1.3;
}

#l13-book .panel {
  background: rgba(255, 255, 255, 0.94);
  border: 2px solid var(--edge, #5d4037);
  border-radius: 12px 18px 10px 16px;
  padding: clamp(0.65rem, 1.2vw, 0.95rem);
  box-shadow: 0 3px 0 rgba(93, 64, 55, 0.07);
}

#l13-book .scene-frame {
  width: 100%;
  aspect-ratio: 4 / 3;
  min-height: 0;
  border-radius: 10px 14px 8px 12px;
  border: 2px solid var(--edge, #5d4037);
  background: var(--l13-scene-bg, linear-gradient(145deg, #0f172a, #1e1b4b));
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
}

#l13-book .scene-frame img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  display: block;
}

/* —— L13 底栏：覆盖 lesson-screen 默认黄蜡笔风，统一青绿主题 —— */
body.has-lesson-pager #app nav.lesson-pager {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 200;
  display: flex;
  align-items: stretch;
  justify-content: stretch;
  gap: 0.28rem;
  padding: 0.28rem 0.4rem;
  padding-bottom: max(0.28rem, env(safe-area-inset-bottom, 0px));
  background: rgba(255, 255, 255, 0.97);
  border-top: 2px solid var(--l13-accent, #0d9488);
  box-shadow: 0 -6px 24px rgba(15, 23, 42, 0.1);
  backdrop-filter: blur(10px);
  font-family: system-ui, -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}

body.has-lesson-pager #app nav.lesson-pager .pager-prev,
body.has-lesson-pager #app nav.lesson-pager .pager-next,
body.has-lesson-pager #app nav.lesson-pager a.l13-index-link {
  flex: 1 1 0;
  min-width: 0;
  min-height: 34px;
  max-height: 38px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0;
  padding: 0.22rem 0.38rem;
  border-radius: 8px;
  border: 1.5px solid var(--edge, #5d4037);
  font-size: clamp(0.7rem, 2vw, 0.78rem);
  font-weight: 800;
  line-height: 1.25;
  cursor: pointer;
  touch-action: manipulation;
  box-shadow: 0 2px 0 rgba(93, 64, 55, 0.12);
  transition: filter 0.15s ease, transform 0.1s ease;
  font-family: inherit;
}

body.has-lesson-pager #app nav.lesson-pager .pager-prev {
  color: #334155;
  background: linear-gradient(180deg, #fff, #f8fafc);
}

body.has-lesson-pager #app nav.lesson-pager a.l13-index-link {
  flex: 0.75 1 0;
  color: var(--l13-accent-ink, #0f766e) !important;
  background: linear-gradient(180deg, #f0fdfa, #ccfbf1) !important;
  border-color: var(--l13-accent, #0d9488) !important;
  text-decoration: none;
  box-shadow: 0 2px 0 rgba(13, 148, 136, 0.2) !important;
}

body.has-lesson-pager #app nav.lesson-pager .pager-next {
  color: #fff !important;
  background: linear-gradient(135deg, var(--l13-accent, #14b8a6), var(--l13-accent-ink, #0d9488)) !important;
  border-color: var(--l13-accent-ink, #0f766e) !important;
  box-shadow: 0 3px 0 rgba(15, 118, 110, 0.35), 0 0 16px rgba(13, 148, 136, 0.25) !important;
}

body.has-lesson-pager #app nav.lesson-pager .pager-mid {
  flex: 0.7 1 0;
  min-width: 2.8rem;
  min-height: 34px;
  max-height: 38px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0;
  padding: 0.2rem 0.35rem;
  border-radius: 8px;
  border: 1.5px solid var(--l13-accent, #0d9488);
  background: linear-gradient(180deg, #fff, #f0fdfa);
  color: var(--l13-accent-ink, #0f766e);
  font-weight: 900;
  font-size: clamp(0.68rem, 1.9vw, 0.76rem);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.9);
  text-shadow: none;
  line-height: 1.2;
  cursor: default;
}

body.has-lesson-pager #app nav.lesson-pager .pager-mid::after {
  display: none;
}

body.has-lesson-pager #app nav.lesson-pager .pager-prev:hover:not(:disabled),
body.has-lesson-pager #app nav.lesson-pager .pager-next:hover:not(:disabled),
body.has-lesson-pager #app nav.lesson-pager a.l13-index-link:hover {
  filter: brightness(1.04);
}

body.has-lesson-pager #app nav.lesson-pager .pager-prev:active:not(:disabled),
body.has-lesson-pager #app nav.lesson-pager .pager-next:active:not(:disabled) {
  transform: translateY(1px);
}

body.has-lesson-pager #app nav.lesson-pager button:disabled {
  opacity: 0.42;
  cursor: not-allowed;
  box-shadow: none;
}

@media (min-width: 640px) {
  body.has-lesson-pager #app nav.lesson-pager {
    gap: 0.32rem;
    padding: 0.32rem 0.5rem;
    padding-bottom: max(0.32rem, env(safe-area-inset-bottom, 0px));
  }
  body.has-lesson-pager #app nav.lesson-pager .pager-prev,
  body.has-lesson-pager #app nav.lesson-pager .pager-next,
  body.has-lesson-pager #app nav.lesson-pager a.l13-index-link,
  body.has-lesson-pager #app nav.lesson-pager .pager-mid {
    min-height: 36px;
    max-height: 40px;
  }
}