:root {
  --page-bg-left: #fdf4e3;
  --page-bg-right: #fbead3;
  --ink: #443021;
  --ink-light: #6b4d30;
  --accent: #bb8a38;
  --accent-dark: #945f23;
  --button-primary: linear-gradient(135deg, #c59a57 0%, #a9742a 48%, #8b561c 100%);
  --button-primary-hover: linear-gradient(135deg, #d8b26e 0%, #b88336 48%, #9b611e 100%);
  --button-secondary: linear-gradient(135deg, #b9935b 0%, #967240 48%, #7a542b 100%);
  --button-secondary-hover: linear-gradient(135deg, #cca771 0%, #a57f47 48%, #855f31 100%);
  --button-cover: linear-gradient(135deg, #8d6742 0%, #704c2c 45%, #523519 100%);
  --button-cover-hover: linear-gradient(135deg, #9f7b53 0%, #7e5935 45%, #5f3f22 100%);
  --paper-fiber: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160' viewBox='0 0 160 160'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cpath fill='%23f2e3c6' d='M0 0h160v160H0z'/%3E%3Cpath d='M119 144c13.807 0 25-11.193 25-25s-11.193-25-25-25-25 11.193-25 25 11.193 25 25 25zM36 66c8.284 0 15-6.716 15-15S44.284 36 36 36 21 42.716 21 51s6.716 15 15 15z' stroke='%23f5d5a5' stroke-width='5' opacity='.45'/%3E%3Cpath d='M33 123c4.418 0 8-3.582 8-8s-3.582-8-8-8-8 3.582-8 8 3.582 8 8 8zm87-72c5.523 0 10-4.477 10-10S125.523 31 120 31s-10 4.477-10 10 4.477 10 10 10z' stroke='%23f3d6a1' stroke-width='3' opacity='.35'/%3E%3C/g%3E%3C/svg%3E");
  --page-margin-vertical: clamp(16px, 2.6vw, 28px);
  --page-margin-inner: clamp(8px, 1vw, 14px);
  --page-margin-outer: clamp(24px, 4vw, 40px);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  font-family: 'Lora', serif;
  color: var(--ink);
  min-height: 100%;
  background: radial-gradient(circle at top, #705536 0%, #3a2817 65%, #21160c 100%);
  overflow: hidden;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  background: radial-gradient(circle at center, rgba(255, 244, 223, 0.12) 0%, rgba(33, 22, 12, 0.82) 100%);
  pointer-events: none;
  z-index: -1;
}

.intro-page {
  position: fixed;
  inset: 0;
  background: radial-gradient(circle at center, rgba(23, 12, 6, 0.7) 0%, rgba(5, 3, 0, 0.95) 100%);
  z-index: 999;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  transition: opacity 0.6s ease;
}

.intro-page.closing {
  opacity: 0;
  pointer-events: none;
}

.library-bg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: brightness(0.75) saturate(0.85);
  transform: scale(1.05);
  animation: fadeLibrary 3s ease-in forwards;
}

.cover-book {
  width: clamp(260px, 28vw, 460px);
  height: auto;
  transform: scale(0) rotateY(720deg);
  animation: zoomInBook 2.8s ease-in-out forwards 0.6s;
  cursor: pointer;
  z-index: 2;
  box-shadow: 0 28px 45px rgba(0, 0, 0, 0.55);
  transition: transform 0.45s ease;
}

.cover-book:hover {
  transform: scale(1.08) rotateY(0deg);
}

.book-stage {
  position: relative;
  width: 100%;
  height: 100vh;
  padding: clamp(8px, 3.5vw, 28px);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: clamp(0.8rem, 2vw, 1.4rem);
  perspective: 2200px;
  transform-style: preserve-3d;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.6s ease;
}

.book-stage.is-open {
  opacity: 1;
  pointer-events: auto;
}

.book-wrapper {
  position: relative;
  width: min(99vw, 1400px);
  height: min(94vh, 860px);
  display: flex;
  align-items: center;
  justify-content: center;
}

.book-shadow {
  position: absolute;
  inset: 12% 6%;
  filter: blur(45px);
  background: radial-gradient(circle at center, rgba(0, 0, 0, 0.45) 0%, rgba(0, 0, 0, 0) 70%);
  transform: translateZ(-60px);
}

.book {
  position: relative;
  width: 100%;
  height: 100%;
  display: flex;
  border-radius: 26px;
  background: linear-gradient(90deg, rgba(52, 36, 20, 0.65) 0%, rgba(32, 21, 12, 0.85) 50%, rgba(52, 36, 20, 0.68) 100%);
  box-shadow:
    0 45px 70px rgba(16, 7, 2, 0.58),
    inset 0 0 25px rgba(0, 0, 0, 0.4);
  transform-style: preserve-3d;
  overflow: hidden;
}

.book::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at center, rgba(255, 255, 255, 0.08) 0%, rgba(0, 0, 0, 0.35) 100%);
  opacity: 0.35;
  pointer-events: none;
}

.book::after {
  content: "";
  position: absolute;
  top: var(--page-margin-vertical);
  bottom: var(--page-margin-vertical);
  left: 50%;
  width: 2px;
  transform: translateX(-1px);
  background: linear-gradient(180deg, rgba(0, 0, 0, 0.25) 0%, rgba(0, 0, 0, 0.05) 50%, rgba(0, 0, 0, 0.32) 100%);
  box-shadow:
    0 0 12px rgba(0, 0, 0, 0.35);
  z-index: 3;
  pointer-events: none;
}

.book-leaf {
  position: relative;
  width: 50%;
  height: 100%;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.04) 0%, rgba(0, 0, 0, 0.2) 100%);
  display: flex;
  justify-content: center;
  perspective: 1600px;
}

.left-leaf {
  border-top-left-radius: 26px;
  border-bottom-left-radius: 26px;
  box-shadow: inset -12px 0 24px rgba(0, 0, 0, 0.32);
}

.right-leaf {
  border-top-right-radius: 26px;
  border-bottom-right-radius: 26px;
  box-shadow: inset 12px 0 24px rgba(0, 0, 0, 0.32);
}

.page-surface {
  position: absolute;
  inset: var(--page-margin-vertical) var(--page-margin-outer);
  background: linear-gradient(90deg, var(--page-bg-left) 0%, var(--page-bg-left) 50%, var(--page-bg-right) 100%);
  background-image:
    var(--paper-fiber),
    linear-gradient(90deg, rgba(255, 255, 255, 0.3) 0%, rgba(210, 180, 140, 0.1) 49%, rgba(210, 180, 140, 0.12) 51%, rgba(255, 255, 255, 0.35) 100%);
  background-blend-mode: multiply;
  border-radius: 18px;
  box-shadow:
    inset 0 0 22px rgba(255, 255, 255, 0.3),
    0 24px 38px rgba(16, 7, 2, 0.35);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  transition: opacity 0.4s ease;
}

.left-leaf .page-surface {
  inset: var(--page-margin-vertical) var(--page-margin-inner) var(--page-margin-vertical) var(--page-margin-outer);
}

.right-leaf .page-surface {
  inset: var(--page-margin-vertical) var(--page-margin-outer) var(--page-margin-vertical) var(--page-margin-inner);
}

.page-surface::before {
  content: "";
  position: absolute;
  inset: clamp(8px, 1.8vw, 16px);
  border-radius: 14px;
  border: 1px solid rgba(176, 137, 74, 0.35);
  pointer-events: none;
}

.page-surface.is-hidden {
  opacity: 0;
  visibility: hidden;
}

.page-surface.is-empty::after {
  content: "";
}

.page-surface::after {
  content: attr(data-page-label);
  position: absolute;
  bottom: clamp(3.2rem, 5vw, 4rem);
  right: clamp(20px, 4vw, 36px);
  font-size: clamp(0.7rem, 1vw, 0.95rem);
  letter-spacing: 0.28em;
  text-transform: uppercase;
  color: rgba(138, 98, 47, 0.7);
  pointer-events: none;
}

.left-leaf .page-surface::after {
  right: auto;
  left: clamp(20px, 4vw, 36px);
  text-align: left;
}

.chapter {
  position: relative;
  display: flex;
  flex-direction: column;
  height: 100%;
  justify-content: flex-start;
  padding: clamp(1.2rem, 2.4vw, 1.8rem);
  gap: clamp(1rem, 2vw, 1.6rem);
  overflow: hidden;
}

.chapter-figure {
  margin: 0;
  border-radius: 14px;
  overflow: hidden;
  box-shadow:
    0 22px 28px rgba(0, 0, 0, 0.25),
    0 0 0 6px rgba(255, 255, 255, 0.4);
  flex: 0 0 clamp(200px, 30vh, 280px);
  display: flex;
}

.chapter-figure img {
  display: block;
  width: 100%;
  height: 100%;
  min-height: 200px;
  object-fit: cover;
  transform: translateY(22px) scale(0.9);
  opacity: 0;
  transition:
    transform 0.85s cubic-bezier(0.19, 1, 0.22, 1) 0.12s,
    opacity 0.6s ease 0.12s;
}

.chapter-text {
  position: relative;
  padding: clamp(1rem, 2.2vw, 1.6rem);
  border-radius: 16px;
  border: 1px solid rgba(182, 144, 91, 0.28);
  flex: 1 1 auto;
  min-height: 0;
  overflow-y: auto;
  background: linear-gradient(180deg, rgba(255, 252, 244, 0.92) 0%, rgba(255, 249, 233, 0.8) 100%);
  box-shadow:
    inset 0 12px 28px rgba(255, 255, 255, 0.45),
    inset 0 -8px 22px rgba(138, 102, 54, 0.18);
  backdrop-filter: blur(1px);
}

.chapter-text::before,
.chapter-text::after {
  content: "";
  position: absolute;
  width: 46px;
  height: 46px;
  background: radial-gradient(circle at center, rgba(187, 138, 56, 0.32) 0%, rgba(255, 255, 255, 0) 75%);
  opacity: 0.75;
}

.chapter-text::before {
  top: -15px;
  left: -18px;
}

.chapter-text::after {
  bottom: -18px;
  right: -16px;
}

.chapter h2 {
  margin: 0 0 clamp(0.6rem, 1.4vw, 1.1rem);
  font-family: 'Cinzel Decorative', cursive;
  font-size: clamp(1.6rem, 2.8vw, 2.2rem);
  letter-spacing: 0.06em;
  text-align: center;
  color: var(--accent-dark);
}

.chapter p {
  margin: 0;
  font-size: clamp(0.95rem, 1.45vw, 1.15rem);
  line-height: 1.65;
  color: var(--ink-light);
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease 0.18s, transform 0.6s ease 0.18s;
}

.chapter p + p {
  margin-top: clamp(0.6rem, 1vw, 0.9rem);
}

.chapter p:first-of-type::first-letter {
  font-family: 'Cinzel Decorative', cursive;
  font-size: clamp(2.4rem, 4.2vw, 3.2rem);
  line-height: 0.95;
  padding-right: 0.35rem;
  color: var(--accent);
  float: left;
}

.book-leaf.active .chapter-figure img,
.book-turner .chapter-figure img {
  opacity: 1;
  transform: translateY(0) scale(0.94);
}

.book-leaf.active .chapter p {
  opacity: 1;
  transform: translateY(0);
}

.book-turner .chapter-figure img {
  transition: none;
}

.book-turner .chapter p {
  opacity: 1;
  transform: none;
  transition: none;
}


.book-turner {
  position: absolute;
  top: 0;
  left: 50%;
  width: 50%;
  height: 100%;
  pointer-events: none;
  transform-style: preserve-3d;
  transform-origin: left center;
  display: none;
  z-index: 5;
}

.book-turner.visible {
  display: block;
}

.book-turner .page-face {
  position: absolute;
  inset: var(--page-margin-vertical) var(--page-margin-outer);
  background: linear-gradient(90deg, var(--page-bg-left) 0%, var(--page-bg-left) 50%, var(--page-bg-right) 100%);
  background-image:
    var(--paper-fiber),
    linear-gradient(90deg, rgba(255, 255, 255, 0.3) 0%, rgba(210, 180, 140, 0.1) 49%, rgba(210, 180, 140, 0.12) 51%, rgba(255, 255, 255, 0.35) 100%);
  background-blend-mode: multiply;
  border-radius: 18px;
  box-shadow:
    inset 0 0 22px rgba(255, 255, 255, 0.3),
    0 24px 38px rgba(16, 7, 2, 0.42);
  overflow: hidden;
  backface-visibility: hidden;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.book-turner .page-face::before {
  content: "";
  position: absolute;
  inset: clamp(12px, 2vw, 20px);
  border-radius: 14px;
  border: 1px solid rgba(176, 137, 74, 0.35);
  pointer-events: none;
}

.book-turner .page-face::after {
  content: attr(data-page-label);
  position: absolute;
  bottom: clamp(18px, 3vw, 28px);
  right: clamp(20px, 4vw, 36px);
  font-size: clamp(0.7rem, 1vw, 0.95rem);
  letter-spacing: 0.28em;
  text-transform: uppercase;
  color: rgba(138, 98, 47, 0.7);
}

.book-turner[data-side="right"] .page-face {
  inset: var(--page-margin-vertical) var(--page-margin-outer) var(--page-margin-vertical) var(--page-margin-inner);
}

.book-turner[data-side="left"] .page-face {
  inset: var(--page-margin-vertical) var(--page-margin-inner) var(--page-margin-vertical) var(--page-margin-outer);
}

.book-turner .page-face.front {
  transform: rotateY(0deg);
}

.book-turner .page-face.back {
  transform: rotateY(180deg);
}

.book-turner.turn-forward {
  left: 50%;
  transform-origin: left center;
  animation: pageTurnForward 1s cubic-bezier(0.19, 1, 0.22, 1) forwards;
}

.book-turner.turn-backward {
  left: 0;
  transform-origin: right center;
  animation: pageTurnBackward 1s cubic-bezier(0.19, 1, 0.22, 1) forwards;
}

.book-turner.turn-backward .page-face::after {
  left: clamp(20px, 4vw, 36px);
  right: auto;
}

.book-turner.turn-forward .page-face::after {
  right: clamp(20px, 4vw, 36px);
}

.page-content {
  position: relative;
  flex: 1 1 auto;
  display: flex;
  flex-direction: column;
  min-height: 0;
}

.page-content > * {
  flex: 1 1 auto;
}

.page-nav-btn {
  position: absolute;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  font-family: 'Cinzel Decorative', cursive;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-dark);
  background: linear-gradient(160deg, rgba(255, 252, 241, 0.8) 0%, rgba(254, 244, 217, 0.65) 100%);
  border: 1px solid rgba(148, 95, 35, 0.28);
  box-shadow:
    0 12px 22px rgba(35, 20, 6, 0.22),
    inset 0 1px 3px rgba(255, 255, 255, 0.35);
  border-radius: 999px;
  transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.3s ease, border-color 0.3s ease;
  padding: 0.35rem 0.85rem;
  font-size: clamp(0.7rem, 0.9vw, 0.85rem);
  z-index: 6;
}

.page-nav-btn span {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: clamp(18px, 2.4vw, 24px);
  height: clamp(18px, 2.4vw, 24px);
  color: transparent;
}

.page-nav-btn--prev,
.page-nav-btn--next {
  width: clamp(40px, 4.6vw, 54px);
  height: clamp(40px, 4.6vw, 54px);
  padding: 0;
  border-radius: 50%;
  font-size: 0;
}

.page-nav-btn--prev span::before,
.page-nav-btn--next span::before,
.page-nav-btn--prev span::after,
.page-nav-btn--next span::after {
  content: "";
  position: absolute;
  display: block;
}

.page-nav-btn--next span::before,
.page-nav-btn--prev span::before {
  top: 50%;
  height: clamp(3px, 0.45vw, 4px);
  border-radius: 999px;
  background: linear-gradient(90deg, rgba(148, 95, 35, 0.2) 0%, rgba(148, 95, 35, 0.9) 100%);
  transform: translateY(-50%);
  box-shadow: 0 0 6px rgba(148, 95, 35, 0.35);
}

.page-nav-btn--next span::after,
.page-nav-btn--prev span::after {
  width: clamp(12px, 1.8vw, 18px);
  height: clamp(12px, 1.8vw, 18px);
  background: linear-gradient(135deg, rgba(155, 102, 41, 0.95) 0%, rgba(215, 164, 93, 0.9) 100%);
  filter: drop-shadow(0 2px 3px rgba(35, 20, 6, 0.25));
}

.page-nav-btn--next span::before {
  left: 18%;
  right: 30%;
}

.page-nav-btn--next span::after {
  right: 16%;
  top: 50%;
  transform: translateY(-50%);
  clip-path: polygon(0 0, 100% 50%, 0 100%);
}

.page-nav-btn--prev span::before {
  left: 30%;
  right: 18%;
  background: linear-gradient(270deg, rgba(148, 95, 35, 0.2) 0%, rgba(148, 95, 35, 0.9) 100%);
}

.page-nav-btn--prev span::after {
  left: 16%;
  top: 50%;
  transform: translateY(-50%) scaleX(-1);
  clip-path: polygon(0 0, 100% 50%, 0 100%);
}

.page-nav-btn--prev {
  bottom: clamp(0.25rem, 1vw, 0.7rem);
  left: clamp(0.25rem, 1vw, 0.7rem);
}

.page-nav-btn--next {
  bottom: clamp(0.25rem, 1vw, 0.7rem);
  right: clamp(0.25rem, 1vw, 0.7rem);
}

.page-nav-btn--cover {
  top: clamp(0.25rem, 1vw, 0.7rem);
  left: clamp(0.25rem, 1vw, 0.7rem);
  padding: 0.4rem 1.1rem;
  font-size: clamp(0.7rem, 0.95vw, 0.9rem);
}

.page-nav-btn:hover:not(:disabled) {
  transform: translateY(-2px);
  box-shadow:
    0 16px 28px rgba(35, 20, 6, 0.35),
    inset 0 2px 5px rgba(255, 255, 255, 0.45);
  background: linear-gradient(160deg, rgba(255, 254, 246, 0.92) 0%, rgba(240, 214, 170, 0.8) 100%);
  border-color: rgba(148, 95, 35, 0.45);
}

.page-nav-btn:active:not(:disabled) {
  transform: translateY(0);
  box-shadow:
    0 8px 14px rgba(35, 20, 6, 0.28),
    inset 0 3px 7px rgba(0, 0, 0, 0.15);
  background: linear-gradient(160deg, rgba(250, 242, 220, 0.75) 0%, rgba(230, 200, 160, 0.65) 100%);
}

.page-nav-btn:disabled,
.page-nav-btn[aria-disabled="true"] {
  opacity: 0.35;
  cursor: not-allowed;
  transform: none;
  box-shadow:
    0 6px 10px rgba(35, 20, 6, 0.18),
    inset 0 1px 2px rgba(255, 255, 255, 0.25);
}

@keyframes pageTurnForward {
  0% {
    transform: rotateY(0deg);
  }
  100% {
    transform: rotateY(-180deg);
  }
}

@keyframes pageTurnBackward {
  0% {
    transform: rotateY(0deg);
  }
  100% {
    transform: rotateY(180deg);
  }
}

@keyframes fadeLibrary {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

@keyframes zoomInBook {
  from {
    transform: scale(0) rotateY(720deg);
  }
  to {
    transform: scale(1) rotateY(0deg);
  }
}

@media (max-width: 900px) {
  .book-stage {
    padding: clamp(10px, 3.2vw, 26px);
  }

  .book-wrapper {
    width: min(99vw, 1000px);
    height: min(94vh, 720px);
  }

  .chapter {
    padding: clamp(1rem, 3.4vw, 1.6rem);
  }

  .chapter-figure {
    flex-basis: clamp(180px, 34vh, 240px);
  }

  .chapter-figure img {
    min-height: clamp(180px, 34vh, 240px);
  }

  .page-nav-btn--prev,
  .page-nav-btn--next {
    width: clamp(34px, 7vw, 44px);
    height: clamp(34px, 7vw, 44px);
  }

  .page-nav-btn--cover {
    padding: 0.35rem 0.9rem;
    font-size: clamp(0.65rem, 1.8vw, 0.85rem);
  }
}

@media (prefers-reduced-motion: reduce) {
  .chapter-figure img {
    transition: none !important;
    opacity: 1;
    transform: translateY(0) scale(0.94);
  }

  .chapter p {
    transition: none !important;
    opacity: 1;
    transform: translateY(0);
  }

  .book-turner.turn-forward,
  .book-turner.turn-backward {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }

  .book-turner {
    transition: none !important;
  }
}