:root {
  color-scheme: dark;
  --paper: #f3f0ea;
  --book-shadow: 0 28px 70px rgba(0, 0, 0, 0.42);
}

* {
  box-sizing: border-box;
}

html,
body {
  width: 100%;
  height: 100%;
  margin: 0;
}

body {
  min-height: 100svh;
  overflow: hidden;
  background:
    radial-gradient(circle at 18% 10%, rgba(108, 124, 135, 0.28), transparent 30%),
    linear-gradient(135deg, #171512 0%, #282521 48%, #101113 100%);
  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.viewer {
  position: relative;
  display: grid;
  grid-template-rows: 1fr auto;
  width: 100%;
  height: 100svh;
  padding: max(14px, env(safe-area-inset-top)) max(14px, env(safe-area-inset-right)) max(14px, env(safe-area-inset-bottom)) max(14px, env(safe-area-inset-left));
}

.book-shell {
  display: grid;
  min-height: 0;
  place-items: center;
}

.book-stage {
  position: relative;
  display: grid;
  width: min(100%, calc((100svh - 86px) * 1.256));
  max-height: calc(100svh - 86px);
  aspect-ratio: 1.256 / 1;
  perspective: 2200px;
}

.book-stage::after {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  left: 50%;
  display: none;
  width: clamp(80px, 12%, 150px);
  background:
    linear-gradient(
      90deg,
      transparent 0%,
      rgba(0, 0, 0, 0.02) 28%,
      rgba(0, 0, 0, 0.05) 49%,
      rgba(0, 0, 0, 0.05) 51%,
      rgba(0, 0, 0, 0.02) 72%,
      transparent 100%
    );
  pointer-events: none;
  transform: translateX(-50%);
  z-index: 9;
}

.book-stage.has-fold::after {
  display: block;
}

.spread {
  position: absolute;
  inset: 0;
  display: grid;
  grid-template-columns: 50% 50%;
  align-items: stretch;
  filter: drop-shadow(0 28px 46px rgba(0, 0, 0, 0.34));
  transform-style: preserve-3d;
}

.spread.full-page {
  grid-template-columns: minmax(0, 1fr);
  width: 50%;
  left: 25%;
}

.page {
  position: relative;
  display: grid;
  overflow: hidden;
  min-width: 0;
  min-height: 0;
  background: var(--paper);
}

.page.left {
  transform-origin: right center;
  margin-right: 0;
}

.page.right {
  transform-origin: left center;
  margin-left: 0;
}

.page.full {
  margin: 0;
}

.page img {
  display: block;
  width: 200%;
  height: 100%;
  max-width: none;
  object-fit: fill;
  background: #fff;
}

.page img.right {
  transform: translateX(-50%);
}

.page.full img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  transform: none;
}

.page::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.page::before {
  display: none;
}

.page.left::after {
  display: none;
}

.page.right::after {
  display: none;
}

.spread.full-page::after,
.page.full::after {
  display: none;
}

.turner {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 50%;
  background: var(--paper);
  transform-style: preserve-3d;
  z-index: 5;
}

.turner.next {
  left: 50%;
  transform-origin: left center;
  animation: turnNext 720ms cubic-bezier(0.2, 0.72, 0.18, 1) both;
}

.turner.prev {
  left: 0;
  transform-origin: right center;
  animation: turnPrev 720ms cubic-bezier(0.2, 0.72, 0.18, 1) both;
}

.turn-face {
  position: absolute;
  inset: 0;
  display: grid;
  overflow: hidden;
  background: var(--paper);
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}

.turn-face img {
  display: block;
  width: 200%;
  height: 100%;
  max-width: none;
  object-fit: fill;
  background: #fff;
}

.turn-face img.right {
  transform: translateX(-50%);
}

.turn-face::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.turner.next .turn-face::after {
  display: none;
}

.turner.prev .turn-face::after {
  display: none;
}

.page-reveal {
  position: absolute;
  top: 0;
  bottom: 0;
  display: grid;
  width: 50%;
  overflow: hidden;
  background: var(--paper);
  z-index: 4;
}

.page-reveal.next {
  left: 0;
  animation: revealNext 720ms cubic-bezier(0.2, 0.72, 0.18, 1) both;
}

.page-reveal.prev {
  right: 0;
  animation: revealPrev 720ms cubic-bezier(0.2, 0.72, 0.18, 1) both;
}

.page-reveal img {
  display: block;
  width: 200%;
  height: 100%;
  max-width: none;
  object-fit: fill;
  background: #fff;
}

.page-reveal img.right {
  transform: translateX(-50%);
}

.page-reveal::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.page-reveal.next::after {
  display: none;
}

.page-reveal.prev::after {
  display: none;
}

.fade-next,
.fade-prev {
  animation: fadeTurn 260ms ease-out both;
}

.loading {
  place-self: center;
  color: rgba(255, 255, 255, 0.78);
  font-size: 15px;
  letter-spacing: 0;
}

.controls {
  display: grid;
  grid-template-columns: 48px minmax(96px, auto) 48px;
  align-items: center;
  justify-content: center;
  gap: 10px;
  height: 58px;
}

.icon-button {
  display: grid;
  width: 48px;
  height: 48px;
  place-items: center;
  padding: 0;
  color: #f8f6f0;
  background: rgba(17, 17, 17, 0.58);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: 999px;
  cursor: pointer;
  font-size: 22px;
  line-height: 1;
  transition: transform 160ms ease, background 160ms ease, opacity 160ms ease;
}

.icon-button:hover {
  background: rgba(17, 17, 17, 0.78);
  transform: translateY(-1px);
}

.icon-button:disabled {
  cursor: default;
  opacity: 0.38;
  transform: none;
}

.page-status {
  min-width: 96px;
  color: rgba(255, 255, 255, 0.84);
  font-size: 13px;
  text-align: center;
  font-variant-numeric: tabular-nums;
}

@keyframes turnNext {
  from {
    filter: brightness(1);
    opacity: 1;
    transform: rotateY(0deg);
  }
  48% {
    filter: brightness(0.74);
    opacity: 0.94;
  }
  to {
    filter: brightness(0.82);
    opacity: 0;
    transform: rotateY(-176deg);
  }
}

@keyframes turnPrev {
  from {
    filter: brightness(1);
    opacity: 1;
    transform: rotateY(0deg);
  }
  48% {
    filter: brightness(0.74);
    opacity: 0.94;
  }
  to {
    filter: brightness(0.82);
    opacity: 0;
    transform: rotateY(176deg);
  }
}

@keyframes revealNext {
  from {
    clip-path: inset(0 0 0 56%);
    opacity: 0.86;
  }
  32% {
    opacity: 0.96;
  }
  to {
    clip-path: inset(0 0 0 0);
    opacity: 1;
  }
}

@keyframes revealPrev {
  from {
    clip-path: inset(0 56% 0 0);
    opacity: 0.86;
  }
  32% {
    opacity: 0.96;
  }
  to {
    clip-path: inset(0 0 0 0);
    opacity: 1;
  }
}

@keyframes fadeTurn {
  from {
    opacity: 0;
    transform: scale(0.985);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

@media (max-aspect-ratio: 4 / 5), (max-width: 760px) {
  .viewer {
    padding: max(10px, env(safe-area-inset-top)) max(10px, env(safe-area-inset-right)) max(10px, env(safe-area-inset-bottom)) max(10px, env(safe-area-inset-left));
  }

  .page.left::after,
  .page.right::after {
    background: linear-gradient(90deg, rgba(255, 255, 255, 0.02), transparent 18%, transparent 82%, rgba(0, 0, 0, 0.04));
  }
}