.c2-book-page { overflow: hidden; background: #f4f3f5; }

.c2-book {
  position: fixed;
  inset: 57px 0 29px;
  display: grid;
  grid-template-columns: minmax(164px, .58fr) minmax(480px, 2.72fr) minmax(218px, .78fr);
  gap: clamp(17px, 2vw, 34px);
  align-items: center;
  padding: 49px 22px 24px;
  overflow: hidden;
}

.c2-book__archive-mode {
  position: absolute;
  top: 10px;
  left: 50%;
  z-index: 45;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 7px;
  font-size: 7px;
  letter-spacing: .09em;
  text-align: center;
  text-transform: uppercase;
  transform: translateX(-50%);
  white-space: nowrap;
}

.c2-book__context { align-self: start; min-width: 0; padding-top: 5px; }
.c2-book__context > p:first-child { margin: 0; font-size: 7px; line-height: 1.35; letter-spacing: .09em; text-transform: uppercase; }
.c2-book__context h1 { max-width: 220px; margin: 12px 0 0; font-family: var(--font-display); font-size: clamp(29px, 2.55vw, 43px); font-weight: 400; line-height: .84; letter-spacing: -.055em; }
.c2-book__context-zh { max-width: 205px; margin: 18px 0 0; font-family: var(--font-zh); font-size: 13px; line-height: 1.4; letter-spacing: .02em; }
.c2-book__context > strong { display: block; margin-top: 7px; font-family: var(--font-display); font-size: 17px; font-weight: 400; letter-spacing: -.02em; }
.c2-book__context dl { margin: 32px 0 0; border-top: 1px solid var(--ink); }
.c2-book__context dl div { display: grid; grid-template-columns: 43px minmax(0, 1fr); gap: 8px; padding: 6px 0; border-bottom: 1px solid var(--faint); font-size: 6px; letter-spacing: .08em; }
.c2-book__context dt { color: var(--muted); }
.c2-book__context dd { margin: 0; text-align: right; }

.c2-book__stage { position: relative; width: 100%; max-width: 1080px; justify-self: center; perspective: 2100px; }
.c2-book__scene {
  --book-scale: 1;
  --book-tilt: 0deg;
  position: relative;
  width: 100%;
  aspect-ratio: 1.414 / 1;
  outline: none;
  perspective: 2100px;
  cursor: grab;
  touch-action: none;
  transform: scale(var(--book-scale)) rotateZ(var(--book-tilt));
  transform-origin: center;
  transition: transform 580ms cubic-bezier(.16,1,.3,1);
  will-change: transform;
}
.c2-book__scene:focus-visible { outline: 1px solid var(--orange); outline-offset: 9px; }
.c2-book__scene.is-dragging { cursor: grabbing; transition: none; }
.c2-book__scene.is-wheel-active { transition: transform 130ms ease-out; }
.c2-book__scene.is-settling { animation: c2-book-settle 620ms cubic-bezier(.16,1,.3,1); }
.c2-book__scene.is-turning { cursor: progress; }

.c2-book__bed { position: absolute; inset: 9px -8px -11px 8px; border: 1px solid rgba(23,23,22,.28); background: #d5d1c7; box-shadow: 9px 13px 0 rgba(23,23,22,.07), 0 22px 45px rgba(23,23,22,.11); }
.c2-book__bed::before,
.c2-book__bed::after,
.c2-book__bed i { content: ""; position: absolute; display: block; border: 1px solid rgba(23,23,22,.2); background: #e6e2da; }
.c2-book__bed::before { inset: -4px 3px 4px -3px; }
.c2-book__bed::after { inset: -8px 7px 8px -6px; z-index: -1; }
.c2-book__bed i:nth-child(1) { top: 8%; right: -8px; bottom: 7%; width: 7px; border-left: 0; background: #dedad1; }
.c2-book__bed i:nth-child(2) { right: 6%; bottom: -8px; left: 7%; height: 7px; border-top: 0; background: #dedad1; }
.c2-book__bed i:nth-child(3) { top: 7%; bottom: 8%; left: -5px; width: 5px; border-right: 0; background: #cfcbc2; }

.c2-book__current,
.c2-book__turning-sheet,
.c2-book__turning-face { position: absolute; inset: 0; margin: 0; }
.c2-book__current { z-index: 5; transform-style: preserve-3d; transition: opacity 130ms ease; }
.c2-book__current.is-under-turn { opacity: .88; }
.c2-book__current img,
.c2-book__turning-face img { display: block; width: 100%; height: 100%; border: 1px solid var(--ink); background: white; object-fit: contain; box-shadow: 0 15px 42px rgba(23,23,22,.13); user-select: none; }
.c2-book__current figcaption,
.c2-book__turning-face figcaption { position: absolute; right: 0; bottom: -18px; left: 0; display: flex; justify-content: space-between; font-size: 6px; letter-spacing: .09em; text-transform: uppercase; }

.c2-book__turning-sheet { z-index: 18; transform-style: preserve-3d; pointer-events: none; will-change: transform; contain: layout paint; }
.c2-book__turning-sheet[data-direction="forward"] { transform-origin: left center; }
.c2-book__turning-sheet[data-direction="backward"] { transform-origin: right center; }
.c2-book__turning-face { overflow: hidden; backface-visibility: hidden; transform-style: preserve-3d; }
.c2-book__turning-face--back { transform: rotateY(180deg); }
.c2-book__turning-sheet__fold { position: absolute; inset: 0; z-index: 4; background: rgba(23,23,22,.14); opacity: 0; backface-visibility: hidden; pointer-events: none; will-change: opacity; }
.c2-book__turning-sheet__edge { position: absolute; top: 0; right: -1px; bottom: 0; z-index: 8; width: 2px; background: rgba(255,255,255,.85); box-shadow: -5px 0 18px rgba(23,23,22,.2); pointer-events: none; }

.c2-book__spine { position: absolute; top: 0; bottom: 0; left: 50%; z-index: 24; width: 1px; background: rgba(23,23,22,.31); box-shadow: -4px 0 9px rgba(23,23,22,.13), 4px 0 9px rgba(23,23,22,.13); pointer-events: none; }
.c2-book__edge-light { position: absolute; top: 0; right: 0; bottom: 0; z-index: 23; width: 1px; background: rgba(255,255,255,.72); box-shadow: -8px 0 20px rgba(255,255,255,.16); opacity: .7; pointer-events: none; }
.c2-book__motion-line { position: absolute; right: 0; bottom: -31px; left: 0; z-index: 24; height: 1px; background: var(--orange); transform: scaleX(0); transform-origin: left; }
.c2-book__motion-line.is-active { animation: c2-book-line 760ms cubic-bezier(.22,1,.36,1) both; }
.c2-book__click-wave { position: absolute; z-index: 30; width: 26px; height: 26px; margin: -13px 0 0 -13px; border: 1px solid var(--orange); border-radius: 50%; pointer-events: none; }

.c2-book-step { position: absolute; top: 50%; z-index: 30; width: 32px; height: 32px; padding: 0; border: 1px solid var(--ink); border-radius: 50%; background: var(--paper); font-size: 12px; cursor: pointer; transform: translateY(-50%); transition: color 180ms ease, background 180ms ease, transform 430ms cubic-bezier(.16,1,.3,1); }
.c2-book-step--previous { left: -49px; }
.c2-book-step--next { right: -49px; }
.c2-book-step:hover { color: var(--paper); background: var(--ink); transform: translateY(-50%) scale(1.1); }
.c2-book-step:active { transform: translateY(-50%) scale(.9); }
.c2-book-step:disabled { opacity: .2; cursor: default; }
.c2-book-step:disabled:hover { color: var(--ink); background: var(--paper); transform: translateY(-50%); }
.c2-book__instructions { position: absolute; right: 0; bottom: -49px; left: 0; margin: 0; color: var(--muted); font-size: 6px; letter-spacing: .1em; text-align: center; text-transform: uppercase; }

.c2-book__readout { align-self: end; min-width: 0; padding: 9px 0 15px 12px; border-top: 1px solid var(--ink); border-left: 1px solid var(--ink); transition: opacity 180ms ease, transform 430ms cubic-bezier(.16,1,.3,1); }
.c2-book__readout.is-updating { opacity: .12; transform: translateY(9px) scale(.985); }
.c2-book__counter { display: block; color: var(--orange); font-size: 8px; letter-spacing: .11em; }
.c2-book__readout h2 { margin: 9px 0 0; overflow-wrap: anywhere; font-family: var(--font-display); font-size: clamp(19px, 2vw, 32px); font-weight: 400; line-height: .86; letter-spacing: -.045em; text-transform: uppercase; }
.c2-book__readout > p { margin: 11px 0 0; font-family: var(--font-zh); font-size: 11px; line-height: 1.45; }
.c2-book__readout dl { margin: 18px 0 0; border-top: 1px solid var(--faint); }
.c2-book__readout dl div { display: grid; grid-template-columns: 1fr auto; padding: 6px 0; border-bottom: 1px solid var(--faint); font-size: 6px; letter-spacing: .08em; }
.c2-book__readout dt { color: var(--muted); }
.c2-book__readout dd { margin: 0; text-align: right; }
.c2-book__readout > a { display: flex; justify-content: space-between; margin-top: 13px; padding: 8px 0; border-top: 1px solid var(--ink); border-bottom: 1px solid var(--ink); font-size: 7px; line-height: 1.3; letter-spacing: .07em; text-transform: uppercase; }
.c2-book__readout > a:hover { color: var(--orange); }
.c2-book__readout > .c2-book__pdf-link { margin-top: 0; border-top: 0; color: var(--muted); }

.c2-book-rail { position: fixed; right: 0; bottom: 29px; left: 0; z-index: 55; display: flex; height: 68px; overflow-x: auto; overflow-y: hidden; border-top: 1px solid var(--line); background: rgba(244,243,245,.97); scrollbar-width: none; }
.c2-book-rail::-webkit-scrollbar { display: none; }
.c2-book-rail button { position: relative; display: grid; flex: 0 0 66px; grid-template-columns: 18px 1fr; gap: 5px; align-items: center; min-width: 0; padding: 7px 5px; border: 0; border-right: 1px solid var(--faint); background: transparent; text-align: left; cursor: pointer; }
.c2-book-rail button::after { content: ""; position: absolute; right: 0; bottom: 0; left: 0; height: 2px; background: var(--orange); transform: scaleX(0); transform-origin: center; transition: transform 440ms cubic-bezier(.16,1,.3,1); }
.c2-book-rail button.is-active::after { transform: scaleX(1); }
.c2-book-rail img { display: block; width: 18px; height: 31px; border: 1px solid rgba(23,23,22,.32); object-fit: cover; filter: grayscale(1); opacity: .38; transition: filter 220ms ease, opacity 220ms ease, transform 440ms cubic-bezier(.16,1,.3,1); }
.c2-book-rail button:hover img,
.c2-book-rail button.is-active img { filter: grayscale(0); opacity: 1; transform: scale(1.08); }
.c2-book-rail span { overflow: hidden; font-size: 6px; letter-spacing: .06em; text-overflow: ellipsis; white-space: nowrap; }
.c2-book-rail strong { display: block; margin-top: 3px; color: var(--muted); font-size: 6px; font-weight: 400; }

@keyframes c2-book-line {
  0% { transform: scaleX(0); transform-origin: left; }
  48% { transform: scaleX(1); transform-origin: left; }
  52% { transform: scaleX(1); transform-origin: right; }
  100% { transform: scaleX(0); transform-origin: right; }
}

@keyframes c2-book-settle {
  0% { transform: scale(.992) rotateZ(var(--book-tilt)); }
  46% { transform: scale(1.006) rotateZ(calc(var(--book-tilt) * -.18)); }
  76% { transform: scale(.998) rotateZ(calc(var(--book-tilt) * .06)); }
  100% { transform: scale(1) rotateZ(0deg); }
}

@media (max-width: 1120px) {
  .c2-book { grid-template-columns: minmax(140px, .5fr) minmax(440px, 2.45fr); }
  .c2-book__readout { position: absolute; right: 22px; bottom: 20px; z-index: 35; width: 228px; padding: 9px 10px 10px; background: rgba(244,243,245,.94); }
  .c2-book__readout > p,
  .c2-book__readout dl,
  .c2-book__readout > .c2-book__pdf-link { display: none; }
  .c2-book__readout h2 { font-size: 20px; }
}

@media (max-width: 760px) {
  .c2-book { display: block; padding: 66px 14px 20px; overflow-y: auto; }
  .c2-book__archive-mode { top: 8px; }
  .c2-book__context { display: flex; align-items: flex-end; justify-content: space-between; padding: 0 0 15px; }
  .c2-book__context > p:first-child,
  .c2-book__context-zh,
  .c2-book__context > strong,
  .c2-book__context dl { display: none; }
  .c2-book__context h1 { max-width: 260px; margin: 0; font-size: 31px; }
  .c2-book__stage { width: calc(100% - 46px); margin: 3vh auto 0; }
  .c2-book-step--previous { left: -39px; }
  .c2-book-step--next { right: -39px; }
  .c2-book__readout { position: relative; right: auto; bottom: auto; width: auto; margin-top: 63px; padding: 8px 0 0; border-left: 0; background: transparent; }
  .c2-book__readout > p { display: block; }
  .c2-book__readout > a { display: none; }
  .c2-book__readout h2 { font-size: 22px; }
  .c2-book-rail button { flex-basis: 54px; grid-template-columns: 1fr; }
  .c2-book-rail img { display: none; }
}

@media (max-width: 480px) {
  .c2-book { padding-top: 61px; }
  .c2-book__context h1 { font-size: 27px; }
  .c2-book__stage { width: calc(100% - 28px); margin-top: 7vh; }
  .c2-book-step { top: calc(100% + 33px); }
  .c2-book-step--previous { left: 0; }
  .c2-book-step--next { right: 0; }
  .c2-book__instructions { bottom: -42px; }
  .c2-book__readout { margin-top: 72px; }
}

@media (prefers-reduced-motion: reduce) {
  .c2-book__scene { transition: none; }
}

/* A spread is two pages: turn only the page beside the spine, never the whole board. */
.c2-book__scene {
  --pointer-light-x: 50%;
  --pointer-light-y: 50%;
  isolation: isolate;
  perspective: 5200px;
}
.c2-book__scene::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  z-index: 26;
  width: 170px;
  height: 170px;
  border-radius: 50%;
  background: rgba(255,255,255,.1);
  filter: blur(31px);
  mix-blend-mode: screen;
  opacity: 0;
  pointer-events: none;
  transform: translate3d(calc(var(--pointer-light-x) - 85px), calc(var(--pointer-light-y) - 85px), 28px);
  transition: opacity 420ms cubic-bezier(.16,1,.3,1);
  will-change: transform, opacity;
}
.c2-book__scene.has-pointer-light::before { opacity: .72; }

.c2-book__turning-sheet {
  --fold-strength: 0;
  top: 0;
  bottom: 0;
  width: 50%;
  height: 100%;
  transform-style: preserve-3d;
  backface-visibility: visible;
  will-change: transform, filter;
}
.c2-book__turning-sheet[data-direction="forward"] { right: 0; left: 50%; transform-origin: left center; }
.c2-book__turning-sheet[data-direction="backward"] { right: 50%; left: 0; transform-origin: right center; }
.c2-book__turning-face { inset: 0; border: 0; }
.c2-book__turning-face img {
  position: absolute;
  top: 0;
  width: 200%;
  max-width: none;
  height: 100%;
  border: 1px solid var(--ink);
  object-fit: fill;
  box-shadow: none;
}
.c2-book__turning-face[data-half="left"] img { left: 0; }
.c2-book__turning-face[data-half="right"] img { left: -100%; }
.c2-book__turning-face figcaption { display: none; }
.c2-book__turning-sheet__fold {
  background: rgba(23,23,22,.14);
  box-shadow: inset 22px 0 38px rgb(23 23 22 / calc(var(--fold-strength) * .28));
}
.c2-book__turning-sheet[data-direction="backward"] .c2-book__turning-sheet__fold {
  background: rgba(23,23,22,.14);
  box-shadow: inset -22px 0 38px rgb(23 23 22 / calc(var(--fold-strength) * .28));
}
.c2-book__turning-sheet[data-direction="forward"] .c2-book__turning-sheet__edge { right: -1px; left: auto; }
.c2-book__turning-sheet[data-direction="backward"] .c2-book__turning-sheet__edge { right: auto; left: -1px; box-shadow: 5px 0 18px rgba(23,23,22,.2); }
.c2-book__turning-sheet__edge { opacity: calc(.35 + var(--fold-strength) * .65); filter: blur(calc(var(--fold-speed) * .45px)); }
.c2-book__current.is-under-turn { opacity: .95; filter: brightness(.93) saturate(.97); }
.c2-book__scene.is-turning .c2-book__bed { box-shadow: 10px 15px 0 rgba(23,23,22,.06), 0 30px 58px rgba(23,23,22,.14); }

@media (prefers-reduced-motion: reduce) {
  .c2-book__scene::before { display: none; }
}

/* Dark presentation skin; geometry and page-turn motion remain unchanged. */
html { background: #050505 !important; }
body.c2-book-page {
  --paper: #050505;
  --ink: #f2f0e9;
  --muted: rgba(242,240,233,.5);
  --faint: rgba(242,240,233,.14);
  --line: rgba(242,240,233,.22);
  background: #050505 !important;
  color: var(--ink);
}
.c2-book-page .c2-header {
  border: 0;
  background: transparent;
  box-shadow: none;
  color: var(--ink);
  backdrop-filter: none;
  -webkit-backdrop-filter: none;
}
.c2-book-page .c2-book { background: transparent; }
.c2-book-page .c2-book__archive-mode { color: var(--muted); background: transparent; }
.c2-book-page .c2-footer { color: var(--muted); border: 0; background: transparent; box-shadow: none; backdrop-filter: none; -webkit-backdrop-filter: none; }
.c2-book-page .c2-book__bed { border-color: rgba(255,255,255,.2); background: #101010; box-shadow: 9px 13px 0 rgba(255,255,255,.025), 0 22px 45px rgba(0,0,0,.62); }
.c2-book-page .c2-book__bed::before,
.c2-book-page .c2-book__bed::after,
.c2-book-page .c2-book__bed i { border-color: rgba(255,255,255,.13); background: #181818; }
.c2-book-page .c2-book__current img,
.c2-book-page .c2-book__turning-face img { border-color: rgba(255,255,255,.42); box-shadow: 0 18px 50px rgba(0,0,0,.68); }
.c2-book-page .c2-book-step { display: none; }
.c2-book-page .c2-book__scene { cursor: grab; }
.c2-book-page .c2-book__scene.is-dragging { cursor: grabbing; }
.c2-book-page .c2-book-rail { display: none !important; }
.c2-book-page .c2-book-rail {
  border-color: var(--line);
  background: rgba(5,5,5,.97);
}
.c2-book-page .c2-book-rail button { color: var(--ink); pointer-events: none; cursor: default; }
.c2-book-page .c2-book__readout { border-color: var(--ink); }

@media (max-width: 1120px) {
  .c2-book-page .c2-book__readout { background: rgba(5,5,5,.94); }
}