/* 《望洞庭》：月下纸景。共享功能来自 lesson-shell-v2，本文件只定义本课视觉与内容布局。 */
body[data-lesson-shell="v2"][data-visual-system="paper-lantern"] {
  --lesson-bg: #b9c9cb;
  --lesson-paper: #f6f4ee;
  --lesson-ink: #1f302b;
  --lesson-muted: #52635f;
  --lesson-accent: #2b625d;
  --lesson-accent-soft: #d9e5e2;
  --lesson-gold: #c49342;
  --lesson-deep: #183d3a;
  --lesson-line: rgba(31, 48, 43, .18);
  --lesson-shadow: 0 28px 90px rgba(17, 40, 43, .2);
  background:
    radial-gradient(circle at 14% 8%, rgba(232, 200, 121, .23), transparent 22rem),
    linear-gradient(180deg, #142b3d 0 38rem, #8da8ad 64rem, #cbd6d4 100%);
}

body[data-visual-system="paper-lantern"] .lesson-topbar {
  background: rgba(13, 37, 49, .95);
  border-bottom-color: rgba(232, 200, 121, .22);
}

body[data-visual-system="paper-lantern"] .return-link::before {
  border-color: rgba(232, 200, 121, .72);
}

body[data-visual-system="paper-lantern"] .lesson-hero {
  min-height: 620px;
  color: #f4f2e9;
  background: #102a39;
  border-color: rgba(232, 200, 121, .28);
  box-shadow: 0 34px 100px rgba(3, 20, 31, .46);
}

body[data-visual-system="paper-lantern"] .hero-copy {
  position: relative;
  z-index: 1;
  padding-inline: clamp(38px, 7vw, 84px);
  background:
    radial-gradient(circle at 18% 20%, rgba(232, 200, 121, .12), transparent 18rem),
    linear-gradient(145deg, #102a39, #173b47);
}

body[data-visual-system="paper-lantern"] .hero-copy::after {
  content: "";
  position: absolute;
  inset: 28px;
  z-index: -1;
  pointer-events: none;
  border: 1px solid rgba(232, 200, 121, .17);
  border-radius: 50% 14px 50% 14px / 18px 50% 18px 50%;
}

body[data-visual-system="paper-lantern"] .lesson-mark,
body[data-visual-system="paper-lantern"] .section-kicker {
  color: #265b56;
}

body[data-visual-system="paper-lantern"] .hero-copy .lesson-mark {
  color: #e8c879;
}

body[data-visual-system="paper-lantern"] .hero-copy h1 {
  margin-block: 20px 12px;
  color: #fbf8ef;
  font-size: clamp(58px, 8vw, 98px);
  font-weight: 650;
  letter-spacing: .12em;
  white-space: nowrap;
}

.poem-author {
  margin: 0 0 22px;
  color: #d8ddd7;
  font-family: var(--lesson-serif);
  font-size: 19px;
  letter-spacing: .12em;
}

body[data-visual-system="paper-lantern"] .hero-lead {
  color: rgba(244, 242, 233, .76);
}

body[data-visual-system="paper-lantern"] .learning-path li {
  color: #f4f2e9;
  background: rgba(232, 200, 121, .12);
  border: 1px solid rgba(232, 200, 121, .23);
}

body[data-visual-system="paper-lantern"] .hero-visual {
  min-height: 620px;
  background: #102a39;
}

body[data-visual-system="paper-lantern"] .hero-visual::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(90deg, rgba(16, 42, 57, .28), transparent 32%),
    radial-gradient(circle at 27% 18%, rgba(232, 200, 121, .12), transparent 25%);
}

body[data-visual-system="paper-lantern"] .hero-visual img {
  object-position: 50% 48%;
  filter: saturate(.82) contrast(1.03);
  animation: lake-breathe 16s ease-in-out infinite alternate;
}

body[data-visual-system="paper-lantern"] .hero-visual figcaption {
  z-index: 1;
  color: #f7f3e8;
  background: rgba(12, 35, 46, .88);
  border: 1px solid rgba(232, 200, 121, .3);
}

@keyframes lake-breathe {
  from { transform: scale(1); }
  to { transform: scale(1.024); }
}

body[data-visual-system="paper-lantern"] .reader-dock {
  background: rgba(14, 46, 52, .96);
  border-color: rgba(232, 200, 121, .24);
  box-shadow: 0 18px 48px rgba(7, 31, 38, .34);
}

body[data-visual-system="paper-lantern"] .mode-switch button[aria-pressed="true"],
body[data-visual-system="paper-lantern"] .reader-actions button {
  color: #183d3a;
  background: #f6f4ee;
}

body[data-visual-system="paper-lantern"] .lesson-section {
  background:
    linear-gradient(90deg, rgba(43, 98, 93, .035) 1px, transparent 1px),
    rgba(246, 244, 238, .97);
  background-size: 34px 100%;
  box-shadow: 0 18px 58px rgba(17, 40, 43, .13);
}

.dongting-original-card {
  padding-block: clamp(36px, 6vw, 66px);
  text-align: center;
  background:
    radial-gradient(circle at 50% 45%, rgba(232, 200, 121, .17), transparent 19rem),
    linear-gradient(180deg, #fbfaf5, #eef3f0);
}

.dongting-original-card::before {
  content: "原诗";
  background: #183d3a;
}

.dongting-original-card [data-testid="textbook-original"] {
  font-size: clamp(25px, 3.8vw, 40px);
  font-weight: 620;
  letter-spacing: .1em;
  line-height: 2.15;
}

.poem-line {
  display: block;
}

.couplet-listen-grid {
  margin: 18px 0 24px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.couplet-listen-card {
  min-width: 0;
  padding: 14px;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: center;
  gap: 14px;
  color: #f6f4ee;
  background: #183d3a;
  border: 1px solid rgba(232, 200, 121, .32);
  border-radius: 14px;
}

.couplet-listen-card strong,
.couplet-listen-card span {
  display: block;
}

.couplet-listen-card strong {
  color: #e8c879;
  font-family: var(--lesson-serif);
  font-size: 18px;
}

.couplet-listen-card span {
  color: rgba(246, 244, 238, .72);
  font-size: 13px;
  line-height: 1.55;
}

.couplet-listen-card button {
  min-width: 76px;
  min-height: 48px;
  padding: 8px 13px;
  color: #183d3a;
  cursor: pointer;
  background: #f6f4ee;
  border: 0;
  border-radius: 999px;
  font-weight: 850;
}

.dongting-pronunciations {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.dongting-pronunciations .sound-card {
  background: linear-gradient(145deg, #eff4f1, #e2ebe7);
  border-color: rgba(43, 98, 93, .16);
}

.dongting-notes {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.dongting-notes .word-note {
  min-height: 142px;
  background: #e9efeb;
  border-top: 4px solid #2b625d;
}

.dongting-notes .word-note strong {
  font-family: var(--lesson-serif);
  font-size: 25px;
}

.distance-section {
  overflow: hidden;
}

.distance-journey {
  position: relative;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
}

.distance-journey::before {
  content: "";
  position: absolute;
  top: 23px;
  right: 4%;
  left: 4%;
  height: 1px;
  background: linear-gradient(90deg, transparent, #8cabaa 12% 88%, transparent);
}

.distance-stage {
  position: relative;
  min-width: 0;
  margin: 0;
  overflow: hidden;
  color: #eef3ef;
  background: #102f38;
  border: 1px solid rgba(232, 200, 121, .22);
  border-radius: 18px;
  box-shadow: 0 18px 42px rgba(14, 42, 48, .16);
}

.distance-index {
  position: relative;
  z-index: 1;
  min-height: 46px;
  padding: 11px 14px;
  color: #e8c879;
  background: rgba(12, 39, 47, .96);
  font-size: 12px;
  font-weight: 900;
  letter-spacing: .09em;
}

.distance-stage img {
  width: 100%;
  aspect-ratio: 9 / 16;
  display: block;
  object-fit: contain;
  background: #102a39;
  transition: transform .55s ease, filter .55s ease;
}

.distance-stage:hover img {
  transform: scale(1.02);
  filter: brightness(1.05);
}

.distance-stage figcaption {
  min-height: 130px;
  padding: 15px;
  color: rgba(238, 243, 239, .75);
  font-size: 14px;
  line-height: 1.65;
}

.distance-stage b {
  display: block;
  margin-bottom: 3px;
  color: #e8c879;
  font-family: var(--lesson-serif);
  font-size: 19px;
}

.metaphor-bridge {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 72px minmax(0, 1fr);
  align-items: stretch;
  gap: 0;
}

.metaphor-side {
  min-width: 0;
  padding: clamp(24px, 5vw, 42px);
  border: 1px solid rgba(31, 48, 43, .15);
}

.metaphor-lake {
  color: #24403e;
  background: linear-gradient(145deg, #dce9e8, #b9d1d3);
  border-radius: 22px 0 0 22px;
}

.metaphor-island {
  color: #f3f1e9;
  background: linear-gradient(145deg, #234e45, #183d3a);
  border-radius: 0 22px 22px 0;
}

.metaphor-label {
  display: block;
  margin-bottom: 14px;
  color: #8a671f;
  font-family: var(--lesson-serif);
  font-size: clamp(38px, 5vw, 58px);
  font-weight: 700;
  letter-spacing: .08em;
}

.metaphor-island .metaphor-label {
  color: #e8c879;
}

.metaphor-side strong {
  display: block;
  font-size: 18px;
}

.metaphor-side p {
  margin: 7px 0 0;
  color: inherit;
  opacity: .78;
}

.metaphor-equals {
  position: relative;
  display: grid;
  place-items: center;
  background: linear-gradient(90deg, #b9d1d3 0 50%, #234e45 50%);
}

.metaphor-equals span,
.metaphor-equals span::after {
  width: 28px;
  height: 3px;
  display: block;
  background: #e8c879;
  border-radius: 2px;
}

.metaphor-equals span::after {
  content: "";
  margin-top: 8px;
}

.metaphor-caution {
  grid-column: 1 / -1;
  margin: 14px 0 0;
  padding: 14px 17px;
  color: #37504b;
  background: #e7eee9;
  border-left: 4px solid #c49342;
  border-radius: 0 12px 12px 0;
}

.dongting-recitation .recite-prompt,
.dongting-recitation .recite-answer {
  white-space: normal;
}

body[data-visual-system="paper-lantern"] .recite-panel {
  color: #f6f4ee;
  background:
    radial-gradient(circle at 84% 12%, rgba(232, 200, 121, .2), transparent 22rem),
    linear-gradient(145deg, #102f38, #183d3a);
}

body[data-visual-system="paper-lantern"] .video-card video {
  max-height: 620px;
  background: #102a39;
}

body[data-visual-system="paper-lantern"] .disclosure,
body[data-visual-system="paper-lantern"] .lesson-footer {
  color: #334d49;
}

@media (max-width: 980px) {
  body[data-visual-system="paper-lantern"] .lesson-hero {
    min-height: 540px;
    grid-template-columns: minmax(0, .9fr) minmax(280px, 1.1fr);
  }

  body[data-visual-system="paper-lantern"] .hero-visual {
    min-height: 540px;
  }

  body[data-visual-system="paper-lantern"] .hero-copy h1 {
    font-size: clamp(45px, 7vw, 68px);
    letter-spacing: .06em;
  }

  .couplet-listen-grid {
    grid-template-columns: 1fr;
  }

  .distance-stage figcaption {
    min-height: 166px;
  }
}

@media (max-width: 680px) {
  body[data-visual-system="paper-lantern"] .lesson-hero {
    min-height: 0;
    grid-template-columns: 1fr;
  }

  body[data-visual-system="paper-lantern"] .hero-copy::after {
    inset: 14px;
  }

  body[data-visual-system="paper-lantern"] .hero-copy h1 {
    margin-top: 14px;
    font-size: clamp(48px, 14vw, 60px);
    letter-spacing: .06em;
  }

  body[data-visual-system="paper-lantern"] .hero-visual {
    min-height: 360px;
    max-height: 390px;
  }

  .dongting-original-card [data-testid="textbook-original"] {
    font-size: clamp(21px, 6vw, 27px);
    letter-spacing: .025em;
    line-height: 2.1;
  }

  .couplet-listen-card {
    grid-template-columns: minmax(0, 1fr) 76px;
  }

  .dongting-pronunciations,
  .dongting-notes {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .dongting-notes .word-note:last-child {
    grid-column: 1 / -1;
  }

  .distance-journey {
    grid-template-columns: 1fr;
  }

  .distance-journey::before {
    display: none;
  }

  .distance-stage {
    display: grid;
    grid-template-columns: minmax(150px, .8fr) minmax(0, 1.2fr);
    grid-template-rows: auto 1fr;
  }

  .distance-index {
    grid-column: 1 / -1;
  }

  .distance-stage img {
    grid-row: 2;
    align-self: stretch;
  }

  .distance-stage figcaption {
    min-height: 0;
    align-self: center;
  }

  .metaphor-bridge {
    grid-template-columns: 1fr;
  }

  .metaphor-lake,
  .metaphor-island {
    border-radius: 18px;
  }

  .metaphor-equals {
    min-height: 54px;
    background: linear-gradient(180deg, #b9d1d3 0 50%, #234e45 50%);
  }

  .metaphor-caution {
    grid-column: auto;
  }
}

@media (max-width: 420px) {
  .couplet-listen-card {
    grid-template-columns: 1fr;
  }

  .couplet-listen-card button {
    width: 100%;
  }

  .distance-stage {
    grid-template-columns: minmax(126px, .88fr) minmax(0, 1.12fr);
  }

  .distance-stage figcaption {
    padding: 12px;
    font-size: 13px;
  }

  .metaphor-label {
    font-size: 36px;
  }
}

@media (prefers-reduced-motion: reduce) {
  body[data-visual-system="paper-lantern"] .hero-visual img {
    animation: none;
  }
}