:root {
  color-scheme: light;
  --night: #102b48;
  --blue: #173b60;
  --sun: #f5c64d;
  --paper: #fffdf7;
  --ink: #173149;
  --red: #d9473f;
}

* { box-sizing: border-box; }

html, body { min-height: 100%; }

body {
  margin: 0;
  overflow: hidden;
  font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  color: white;
  background:
    radial-gradient(circle at 18% 16%, rgba(245, 198, 77, .18), transparent 22rem),
    radial-gradient(circle at 84% 86%, rgba(84, 173, 218, .18), transparent 28rem),
    linear-gradient(145deg, var(--night), var(--blue));
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  opacity: .16;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 180 180' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.72' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='.22'/%3E%3C/svg%3E");
}

button { font: inherit; }

.gallery {
  min-height: 100dvh;
  display: grid;
  grid-template-rows: auto 1fr auto;
  padding: max(1.25rem, env(safe-area-inset-top)) 1rem max(1.2rem, env(safe-area-inset-bottom));
}

.brand {
  justify-self: center;
  display: flex;
  align-items: center;
  gap: .65rem;
  font-size: .75rem;
  font-weight: 700;
  letter-spacing: .2em;
  color: rgba(255,255,255,.7);
}

.brand-dot {
  width: .65rem;
  height: .65rem;
  border-radius: 50%;
  background: var(--sun);
  box-shadow: 0 0 0 .28rem rgba(245,198,77,.14);
}

.stage {
  position: relative;
  display: grid;
  place-items: center;
  min-height: 0;
  perspective: 1800px;
  user-select: none;
  -webkit-user-select: none;
  touch-action: pan-y;
}

.book {
  position: relative;
  width: min(72vw, 36rem);
  aspect-ratio: 7 / 9.7;
  transform-style: preserve-3d;
  transform: rotateX(2deg) rotateY(-4deg);
  transition: transform .7s cubic-bezier(.2,.7,.2,1);
  cursor: pointer;
}

.book.is-open { transform: rotateX(1deg) rotateY(0); }

.book-shadow {
  position: absolute;
  width: min(78vw, 40rem);
  height: 2.2rem;
  top: calc(50% + min(36vw, 18rem));
  border-radius: 50%;
  background: rgba(2, 12, 22, .55);
  filter: blur(1.2rem);
  transform: translateY(1rem);
}

.sheet {
  position: absolute;
  inset: 0;
  transform-origin: 1.5% center;
  transform-style: preserve-3d;
  transition: transform .9s cubic-bezier(.55,.02,.18,1), filter .5s;
  will-change: transform;
}

.sheet.flipped { transform: rotateY(-180deg); }

.face {
  position: absolute;
  inset: 0;
  overflow: hidden;
  border-radius: .25rem .8rem .8rem .25rem;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  box-shadow: inset 1.1rem 0 1.5rem rgba(31, 40, 50, .08), 0 1.2rem 3.2rem rgba(0,0,0,.25);
}

.back {
  transform: rotateY(180deg);
  background: linear-gradient(90deg, #efe9da, var(--paper) 16%);
}

.cover {
  display: grid;
  grid-template-rows: 1fr auto 1fr;
  align-items: center;
  padding: 10% 11%;
  text-align: center;
  color: #fff8dc;
  background:
    linear-gradient(110deg, rgba(255,255,255,.11), transparent 18%, transparent 78%, rgba(0,0,0,.12)),
    var(--red);
  border: .22rem solid rgba(255, 234, 170, .72);
  outline: .08rem solid rgba(255,255,255,.22);
  outline-offset: -.75rem;
}

.cover-kicker {
  align-self: end;
  margin: 0 0 1.2rem;
  font-size: clamp(.75rem, 2.3vw, 1rem);
  letter-spacing: .32em;
}

.cover h1 {
  margin: 0;
  font-family: "STKaiti", "KaiTi", "Songti SC", serif;
  font-size: clamp(2.5rem, 9vw, 5.2rem);
  font-weight: 700;
  letter-spacing: .08em;
  text-shadow: 0 .12rem 0 rgba(87,25,20,.25);
}

.cover-mark {
  align-self: start;
  justify-self: center;
  margin-top: 1.4rem;
  width: 3.25rem;
  aspect-ratio: 1;
  display: grid;
  place-items: center;
  border: .12rem solid var(--sun);
  border-radius: 50%;
  color: var(--sun);
  font-family: "STKaiti", "KaiTi", serif;
  font-size: 1rem;
}

.paper {
  display: grid;
  grid-template-rows: 1fr auto;
  padding: clamp(.8rem, 3vw, 1.5rem);
  background:
    linear-gradient(90deg, rgba(200,190,170,.16), transparent 9%),
    var(--paper);
  color: var(--ink);
  border: 1px solid rgba(90, 80, 60, .18);
}

.art-frame {
  min-height: 0;
  display: grid;
  place-items: center;
  overflow: hidden;
  background: white;
  border: 1px solid rgba(26,49,71,.09);
  box-shadow: 0 .5rem 1.4rem rgba(32,46,56,.1);
}

.art-frame img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: contain;
  pointer-events: none;
}

.caption {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
  padding: .8rem .25rem .05rem;
  font-size: clamp(.86rem, 2.4vw, 1rem);
}

.caption strong { font-weight: 650; }
.caption span { color: #74818a; font-size: .82em; letter-spacing: .08em; }

.end-page {
  display: grid;
  place-items: center;
  padding: 2rem;
  text-align: center;
  background: var(--paper);
  color: var(--ink);
  border: 1px solid rgba(90,80,60,.18);
}

.end-page p {
  margin: 0;
  font-family: "STKaiti", "KaiTi", serif;
  font-size: clamp(2rem, 7vw, 3.6rem);
}

.end-page small { display: block; margin-top: 1rem; color: #7a8790; font-size: 1rem; }

.controls {
  justify-self: center;
  display: grid;
  grid-template-columns: 3rem minmax(12rem, 20rem) 3rem;
  align-items: center;
  gap: .6rem;
}

.nav-button {
  width: 3rem;
  height: 3rem;
  border: 1px solid rgba(255,255,255,.24);
  border-radius: 50%;
  color: white;
  background: rgba(255,255,255,.09);
  backdrop-filter: blur(.4rem);
  cursor: pointer;
  transition: background .2s, transform .2s, opacity .2s;
}

.nav-button:hover:not(:disabled) { background: rgba(255,255,255,.18); transform: translateY(-1px); }
.nav-button:focus-visible { outline: .18rem solid var(--sun); outline-offset: .18rem; }
.nav-button:disabled { opacity: .28; cursor: default; }

.status {
  margin: 0;
  text-align: center;
  font-size: .9rem;
  color: rgba(255,255,255,.78);
}

@media (min-width: 760px) {
  .gallery { padding-top: 1.6rem; }
  .book { width: min(46vh, 36rem); }
  .book-shadow { width: min(54vh, 40rem); top: calc(50% + min(23vh, 18rem)); }
}

@media (max-height: 700px) {
  .brand { display: none; }
  .gallery { padding-top: .7rem; }
  .book { width: min(68vh, 27rem); }
}

@media (prefers-reduced-motion: reduce) {
  .sheet, .book, .nav-button { transition-duration: .01ms; }
}