:root {
  --wall: #efe6d4;
  --wall-deep: #d9cbb0;
  --ink: #3a3326;
  --ink-soft: #7a6d58;
  --accent: #1f5a44;
  --gold: #c99c40;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --wall: #1a1d22;
    --wall-deep: #0e1013;
    --ink: #ece3cf;
    --ink-soft: #a89c84;
    --accent: #6fbf98;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --wall: #1a1d22; --wall-deep: #0e1013; --ink: #ece3cf; --ink-soft: #a89c84; --accent: #6fbf98; color-scheme: dark;
}

* { box-sizing: border-box; }
html, body { margin: 0; height: 100%; }
body {
  background: var(--wall);
  color: var(--ink);
  font-family: Inter, system-ui, sans-serif;
  overflow: hidden;
  -webkit-tap-highlight-color: transparent;
}

.room { position: fixed; inset: 0; z-index: 0; pointer-events: none; }
.room-paint { width: 100%; height: 100%; display: block; }

/* ---------- the book on its own in the room ---------- */
.scene {
  position: fixed; inset: 0; z-index: 1;
  display: grid; place-items: center;
  transition: opacity 1.2s ease;
  touch-action: none;
}
.stage { position: relative; display: grid; justify-items: center; gap: clamp(28px, 6vh, 56px); perspective: 1700px; }
.holder { position: relative; transition: transform 1.6s cubic-bezier(.45, 0, .2, 1); }

.book {
  /* the size of one cover; the page block and spine are sized from it */
  --bw: clamp(190px, min(62vw, 42vh), 330px);
  /* the family's pocket mushaf: 1 : 1.44, about a quarter as thick as it is wide;
     a soft cover, so it sits flush with the pages and has no boards */
  --bh: calc(var(--bw) * 1.442);
  --bt: calc(var(--bw) * 0.248);
  --board: calc(var(--bw) * 0.004);
  --inset: calc(var(--bw) * 0.006);
  --corner: calc(var(--bw) * 0.028);
  position: relative;
  width: var(--bw); height: var(--bh);
  transform-style: preserve-3d;
  cursor: grab;
  outline: none;
  will-change: transform;
}
.book:active { cursor: grabbing; }
.book:focus-visible .cover-out { outline: 2px dashed var(--gold); outline-offset: 12px; }

/* its shadow on the wall behind, moving as it leans */
.shadow {
  /* a soft shadow from a box-shadow, painted once (a blur filter here was redrawn every frame).
     The box sits well inside the book, so only its blurred edge shows */
  position: absolute; left: 12%; right: 12%; top: 14%; bottom: 17%;
  border-radius: 26px;
  box-shadow: 0 34px 56px 22px rgba(40, 28, 14, .3), 0 14px 22px 8px rgba(40, 28, 14, .12);
  transform: translate(var(--sx, 0px), var(--sy, 26px)) scaleX(var(--sw, 1));
  will-change: transform;
  transition: opacity .6s ease;
}
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .shadow { box-shadow: 0 26px 54px 14px rgba(0, 0, 0, .55), 0 10px 18px 2px rgba(0, 0, 0, .25); } }

.turner { position: absolute; inset: 0; transform-style: preserve-3d; }
.turner canvas { display: block; width: 100%; height: 100%; }

.face, .edge, .leaf, .cover { position: absolute; transform-style: preserve-3d; }
.face { left: 0; top: 0; width: var(--bw); height: var(--bh); border-radius: var(--corner); overflow: hidden; backface-visibility: hidden; -webkit-backface-visibility: hidden; }
.back-cover { transform: translateZ(calc(var(--bt) / -2)) rotateY(180deg); }
.spine {
  left: calc((var(--bw) - var(--bt)) / 2); width: var(--bt);
  border-radius: calc(var(--bt) * .06);
  transform: rotateY(90deg) translateZ(calc(var(--bw) / 2 - var(--bt) * .02));
}

/* the page block sits a little inside the boards */
.edge { backface-visibility: hidden; -webkit-backface-visibility: hidden; }
.edge-fore {
  top: var(--inset); height: calc(var(--bh) - var(--inset) * 2);
  left: calc((var(--bw) - var(--bt)) / 2); width: calc(var(--bt) - var(--board) * 2);
  margin-left: var(--board);
  transform: rotateY(-90deg) translateZ(calc(var(--bw) / 2 - var(--inset)));
}
.edge-top, .edge-bottom {
  left: var(--inset); width: calc(var(--bw) - var(--inset) * 1.4);
  top: calc((var(--bh) - var(--bt)) / 2); height: calc(var(--bt) - var(--board) * 2);
  margin-top: var(--board);
}
.edge-top { transform: rotateX(90deg) translateZ(calc(var(--bh) / 2 - var(--inset))); }
.edge-bottom { transform: rotateX(-90deg) translateZ(calc(var(--bh) / 2 - var(--inset))); }

.first-leaf .mp { position: absolute; inset: 0; transform: none; padding: 3%; }
.first-leaf {
  --W: calc(var(--bw) - var(--inset) * 1.4);
  background: #fbf6e8; overflow: hidden;
  left: var(--inset); top: var(--inset);
  width: calc(var(--bw) - var(--inset) * 1.4); height: calc(var(--bh) - var(--inset) * 2);
  transform: translateZ(calc(var(--bt) / 2 - var(--board)));
  box-shadow: inset 0 0 0 1px rgba(120, 95, 60, .12);
}

/* the front cover swings open on the spine (the right edge) */
.cover {
  left: 0; top: 0; width: var(--bw); height: var(--bh);
  transform-origin: 100% 50%;
  transform: translateZ(calc(var(--bt) / 2)) rotateY(var(--open, 0deg));
}
.cover-face { position: absolute; inset: 0; border-radius: var(--corner); overflow: hidden; backface-visibility: hidden; -webkit-backface-visibility: hidden; }
.cover-out { box-shadow: inset -6px 0 10px -6px rgba(0, 0, 0, .55); }
.cover-in { transform: rotateY(180deg); }
/* left alone, the cover lifts a little at its edge, as if to say: open me */
.book.nudge .cover { animation: cover-peek 1.5s cubic-bezier(.3, .7, .3, 1); }
@keyframes cover-peek {
  0%, 100% { transform: translateZ(calc(var(--bt) / 2)) rotateY(0deg); }
  30% { transform: translateZ(calc(var(--bt) / 2)) rotateY(28deg); }
  55% { transform: translateZ(calc(var(--bt) / 2)) rotateY(4deg); }
  70% { transform: translateZ(calc(var(--bt) / 2)) rotateY(11deg); }
}

.hint {
  margin: 0; padding: 0 16px; max-width: min(440px, 100vw); text-align: center; line-height: 1.5;
  font-size: 14px; letter-spacing: .02em; color: var(--ink-soft);
  transition: opacity .4s ease;
  animation: pulse 3.2s ease-in-out infinite;
}
.hint.nudge { animation: hint-hop 1.2s ease; }
@keyframes pulse { 50% { opacity: .5; } }
@keyframes hint-hop { 0%, 100% { transform: none; } 25% { transform: translateY(-5px); color: var(--accent); } 50% { transform: none; } 65% { transform: translateY(-2px); } }
.scene.open .hint { opacity: 0; }

/* opening: the book comes towards you and dissolves into the open pages */
.stage { transition: transform 1.6s cubic-bezier(.5, 0, .2, 1), opacity 1.2s ease .2s; }
.scene.leaving { pointer-events: none; }
.scene.leaving .stage { transform: scale(1.55); opacity: 0; }

@media (prefers-reduced-motion: reduce) {
  .hint, .book.nudge .cover, .hint.nudge { animation: none; }
}

/* the one-time suggestion to keep the mushaf on the home screen */
.install {
  position: absolute; top: calc(100% + 14px); left: 50%; z-index: 4; /* under the hint, without moving the book */
  display: flex; align-items: center; gap: 10px;
  width: min(420px, calc(100vw - 32px)); padding: 10px 10px 10px 12px;
  background: rgba(255, 252, 244, .92); border: 1px solid rgba(120, 95, 60, .18); border-radius: 16px;
  box-shadow: 0 8px 24px rgba(60, 40, 20, .14);
  font: 400 13px/1.4 Inter, system-ui, sans-serif; color: var(--ink);
  transform: translate(-50%, 10px); opacity: 0; transition: opacity .4s ease, transform .4s ease;
}
.install[hidden] { display: none; }
.install.shown { transform: translate(-50%, 0); opacity: 1; }
.install img { border-radius: 8px; flex: none; }
.install-text { margin: 0; flex: 1; }
.install-text svg { width: 16px; height: 16px; vertical-align: -3px; color: #2f6fd6; }
.install-go { flex: none; border: 0; border-radius: 999px; padding: 7px 14px; background: #7a2a36; color: #fff; font: 600 13px Inter, system-ui, sans-serif; }
.install-x { flex: none; width: 30px; height: 30px; border: 0; background: none; color: var(--ink-soft); font-size: 20px; line-height: 1; cursor: pointer; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .install { background: rgba(40, 42, 48, .94); border-color: rgba(255, 255, 255, .1); } }

/* opened from the home screen: no browser bars, so keep clear of the notch and the home bar */
.standalone .reader { padding-top: max(14px, env(safe-area-inset-top)); }

/* ---------- the ribbon's tail below the closed book (js/ribbon.js) ---------- */
.ribbon-closed {
  position: absolute; z-index: 2;
  left: calc(var(--bw) * .83); top: calc(var(--bh) - var(--inset) * 2);
  width: calc(var(--bw) * .046); height: calc(var(--bh) * .16);
  transform: translateZ(calc(var(--bt) * .18));
  cursor: grab; touch-action: none;
}
/* easier to catch than it looks */
.ribbon-closed::after { content: ''; position: absolute; left: -16px; right: -16px; top: 0; bottom: -10px; }
.rc-swing {
  position: absolute; inset: 0; transform-origin: 50% 0;
  transform: translateY(var(--pull, 0px));
  animation: ribbon-sway 3.4s ease-in-out infinite;
}
.rc-band {
  position: absolute; inset: 0;
  background: linear-gradient(90deg, #5a1b26, #8d3443 42%, #9a3d4c 58%, #5f1e29);
  clip-path: polygon(0 0, 100% 0, 100% 100%, 50% 88%, 0 100%);
  box-shadow: inset 0 6px 6px -4px rgba(0, 0, 0, .35);
}
@keyframes ribbon-sway { 0%, 100% { rotate: 3deg; } 50% { rotate: -4deg; } }
@media (prefers-reduced-motion: reduce) { .rc-swing { animation: none; } }