:root {
  --ink: #171514;
  --muted: #6e6962;
  --line: #ded8ce;
  --paper: #f7f5f0;
  --surface: #ffffff;
  --shadow: 0 22px 60px rgba(23, 21, 20, 0.16);
  --toolbar-height: 72px;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
  background: var(--paper);
  color: var(--ink);
  font-family: "Helvetica Neue", Arial, sans-serif;
}

button,
input {
  font: inherit;
}

.reader-shell {
  min-height: 100vh;
  display: grid;
  grid-template-rows: auto 1fr auto;
}

.reader-toolbar {
  min-height: var(--toolbar-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 16px 24px;
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(12px);
  position: sticky;
  top: 0;
  z-index: 5;
}

.brand {
  display: grid;
  gap: 4px;
  min-width: 0;
}

.brand-name {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 18px;
  letter-spacing: 0.28em;
  white-space: nowrap;
}

.collection-name {
  color: var(--muted);
  font-size: 13px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.toolbar-actions {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.icon-button,
.download-link {
  min-height: 38px;
  border: 1px solid var(--line);
  background: #ffffff;
  color: var(--ink);
  text-decoration: none;
  display: inline-grid;
  place-items: center;
  cursor: pointer;
}

.icon-button {
  min-width: 38px;
  width: auto;
  padding: 0 10px;
  font-size: 19px;
}

.icon-button--text {
  width: auto;
  min-width: 58px;
  padding: 0 10px;
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.icon-button.is-muted {
  color: var(--muted);
  background: #f4f1eb;
}

.download-link {
  padding: 0 14px;
  font-size: 13px;
}

.icon-button:hover,
.download-link:hover,
.icon-button:focus-visible,
.download-link:focus-visible {
  border-color: var(--ink);
  outline: none;
}

.reader-layout {
  height: calc(100vh - var(--toolbar-height) - 58px);
  min-height: 480px;
  display: grid;
  grid-template-columns: 150px 1fr;
  overflow: hidden;
}

.thumbnail-panel {
  min-height: 0;
  border-right: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.55);
  overflow: auto;
}

.thumbnail-panel.is-hidden {
  display: none;
}

.reader-layout:has(.thumbnail-panel.is-hidden) {
  grid-template-columns: 1fr;
}

.thumbnail-list {
  display: grid;
  gap: 10px;
  padding: 14px;
}

.thumbnail {
  border: 1px solid transparent;
  background: transparent;
  padding: 0;
  cursor: pointer;
  display: grid;
  gap: 5px;
  color: var(--muted);
  text-align: center;
  font-size: 11px;
}

.thumbnail img {
  width: 100%;
  aspect-ratio: var(--page-aspect, 1075 / 1510);
  object-fit: cover;
  background: #ffffff;
  border: 1px solid var(--line);
}

.thumbnail.is-active img {
  border-color: var(--ink);
  box-shadow: 0 10px 28px rgba(23, 21, 20, 0.16);
}

.book-stage {
  min-width: 0;
  height: 100%;
  position: relative;
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr) 42px;
  align-items: center;
  padding: 8px 0;
}

.book-viewport {
  min-height: 0;
  overflow: auto;
  display: grid;
  place-items: center;
  padding: 6px;
  position: relative;
  perspective: 2200px;
  perspective-origin: center center;
}

.book-spread {
  --zoom: 1;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
  width: min(calc(100vw - 110px), calc((100vh - 112px) * var(--spread-ratio, 1.42)));
  max-width: 1480px;
  transform: scale(var(--zoom));
  transform-origin: center center;
  transition: transform 240ms ease, opacity 240ms ease, filter 240ms ease;
  position: relative;
}

.book-spread.is-turning {
  filter: brightness(0.96);
  opacity: 0.72;
}

.book-spread:not(.single-page)::after {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  left: 50%;
  z-index: 2;
  width: 34px;
  pointer-events: none;
  transform: translateX(-50%);
  background:
    linear-gradient(90deg, rgba(23, 21, 20, 0.16), rgba(255, 255, 255, 0.18), rgba(23, 21, 20, 0.1)),
    radial-gradient(ellipse at center, rgba(23, 21, 20, 0.18), transparent 66%);
  filter: blur(7px);
  opacity: 0.44;
}

.book-spread.single-page {
  grid-template-columns: minmax(0, 1fr);
  width: min(calc(100vw - 110px), calc((100vh - 112px) * var(--single-page-ratio, 0.71)));
}

.page-frame {
  aspect-ratio: var(--page-aspect, 1075 / 1510);
  background: var(--surface);
  box-shadow: var(--shadow);
  overflow: hidden;
  position: relative;
}

.book-spread:not(.single-page) .page-frame:first-child {
  box-shadow: -18px 24px 58px rgba(23, 21, 20, 0.12);
}

.book-spread:not(.single-page) .page-frame:last-child {
  box-shadow: 18px 24px 58px rgba(23, 21, 20, 0.12);
}

.page-frame img {
  width: 100%;
  height: 100%;
  display: block;
  object-fit: contain;
}

.page-turner {
  position: absolute;
  z-index: 4;
  overflow: visible;
  pointer-events: none;
  background: #ffffff;
  transform-style: preserve-3d;
  backface-visibility: hidden;
  box-shadow: 0 26px 60px rgba(23, 21, 20, 0.24);
  filter: drop-shadow(0 30px 34px rgba(23, 21, 20, 0.22));
  will-change: opacity, transform;
}

.page-turner::before,
.page-turner::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 3;
  pointer-events: none;
}

.page-turner::before {
  background: linear-gradient(90deg, rgba(255, 255, 255, 0.46), transparent 18%, transparent 70%, rgba(23, 21, 20, 0.3));
  opacity: 0;
  animation: paperSweep 1100ms cubic-bezier(0.18, 0.78, 0.22, 1) both;
}

.page-turner::after {
  inset: -1% -8% -1% auto;
  width: 22%;
  background: radial-gradient(ellipse at center, rgba(23, 21, 20, 0.34), transparent 68%);
  filter: blur(16px);
  opacity: 0;
  transform: translateZ(-24px);
  animation: turningShadow 1100ms cubic-bezier(0.18, 0.78, 0.22, 1) both;
}

.page-turner--next {
  transform-origin: left center;
  animation: bookPageNext 1100ms cubic-bezier(0.18, 0.78, 0.22, 1) both;
}

.page-turner--prev {
  transform-origin: right center;
  animation: bookPagePrev 1100ms cubic-bezier(0.18, 0.78, 0.22, 1) both;
}

.page-turner__face {
  position: absolute;
  inset: 0;
  overflow: hidden;
  background: #ffffff;
  backface-visibility: hidden;
  transform-style: preserve-3d;
}

.page-turner__face::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(90deg, rgba(255, 255, 255, 0.22), transparent 24%, transparent 62%, rgba(23, 21, 20, 0.2)),
    radial-gradient(ellipse at 82% 50%, rgba(255, 255, 255, 0.28), transparent 42%);
  mix-blend-mode: multiply;
}

.page-turner__face img {
  width: 100%;
  height: 100%;
  display: block;
  object-fit: contain;
}

.page-turner__face--back {
  transform: rotateY(180deg);
}

.page-turner--prev .page-turner__face--back {
  transform: rotateY(-180deg);
}

@keyframes bookPageNext {
  0% {
    transform: rotateY(0deg) translateX(0) translateZ(0) skewY(0deg);
    filter: brightness(1);
    opacity: 1;
  }
  18% {
    transform: rotateY(-28deg) translateX(-2.5%) translateZ(38px) skewY(-0.7deg);
    filter: brightness(1.04);
    opacity: 1;
  }
  52% {
    transform: rotateY(-104deg) translateX(-16%) translateZ(72px) skewY(-1.8deg);
    filter: brightness(0.88);
    opacity: 1;
  }
  100% {
    transform: rotateY(-180deg) translateX(-28%) translateZ(0) skewY(0deg);
    filter: brightness(0.74);
    opacity: 0;
  }
}

@keyframes bookPagePrev {
  0% {
    transform: rotateY(0deg) translateX(0) translateZ(0) skewY(0deg);
    filter: brightness(1);
    opacity: 1;
  }
  18% {
    transform: rotateY(28deg) translateX(2.5%) translateZ(38px) skewY(0.7deg);
    filter: brightness(1.04);
    opacity: 1;
  }
  52% {
    transform: rotateY(104deg) translateX(16%) translateZ(72px) skewY(1.8deg);
    filter: brightness(0.88);
    opacity: 1;
  }
  100% {
    transform: rotateY(180deg) translateX(28%) translateZ(0) skewY(0deg);
    filter: brightness(0.74);
    opacity: 0;
  }
}

@keyframes paperSweep {
  0%,
  100% {
    opacity: 0;
    transform: translateX(0);
  }
  48% {
    opacity: 0.88;
    transform: translateX(-18%);
  }
}

@keyframes turningShadow {
  0%,
  100% {
    opacity: 0;
    transform: translateX(0) translateZ(-24px) scaleX(0.7);
  }
  52% {
    opacity: 0.82;
    transform: translateX(-42%) translateZ(-24px) scaleX(1.2);
  }
}

.turn-button {
  width: 34px;
  height: 68px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.88);
  color: var(--ink);
  font-size: 36px;
  line-height: 1;
  cursor: pointer;
}

.turn-button:hover,
.turn-button:focus-visible {
  border-color: var(--ink);
  outline: none;
}

.turn-button:disabled {
  color: rgba(23, 21, 20, 0.22);
  cursor: default;
}

.reader-status {
  display: grid;
  grid-template-columns: auto minmax(180px, 1fr);
  gap: 16px;
  align-items: center;
  padding: 14px 24px;
  background: rgba(255, 255, 255, 0.92);
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 13px;
}

#pageSlider {
  width: 100%;
  accent-color: var(--ink);
}

@media (max-width: 900px) {
  .reader-toolbar {
    display: grid;
  }

  .toolbar-actions {
    justify-content: flex-start;
  }

  .reader-layout {
    grid-template-columns: 1fr;
  }

  .thumbnail-panel {
    display: none;
  }

  .book-stage {
    grid-template-columns: 36px minmax(0, 1fr) 36px;
    padding: 6px 0;
  }

  .book-spread,
  .book-spread.single-page {
    grid-template-columns: minmax(0, 1fr);
    width: min(100%, calc((100vh - 160px) * 0.71));
    gap: 0;
  }

  .turn-button {
    width: 30px;
    height: 58px;
    font-size: 28px;
  }

  .reader-status {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 520px) {
  .reader-toolbar {
    padding: 14px;
  }

  .brand-name {
    font-size: 15px;
    letter-spacing: 0.18em;
  }

  .download-link {
    width: 100%;
  }

  .book-stage {
    grid-template-columns: 36px minmax(0, 1fr) 36px;
  }

  .book-spread,
  .book-spread.single-page {
    width: calc(100vw - 92px);
  }

  .reader-status {
    padding: 12px 14px;
  }
}