:root {
  --bg: #0d0b14;
  --bg2: #17121f;
  --gold: #e8b45a;
  --gold-2: #f6d999;
  --saffron: #e2733a;
  --text: #f3ece0;
  --muted: #a99f92;
  --glass: rgba(255, 255, 255, 0.06);
  --glass-b: rgba(255, 255, 255, 0.12);
  --flip-ms: 800ms;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html, body {
  height: 100%;
  overflow: hidden;
  background: radial-gradient(ellipse at top, #241a2e 0%, var(--bg) 60%);
  color: var(--text);
  font-family: 'Outfit', system-ui, sans-serif;
}

.bg-glow {
  position: fixed; inset: 0; pointer-events: none;
  background:
    radial-gradient(600px 400px at 15% 85%, rgba(226,115,58,.18), transparent 70%),
    radial-gradient(700px 500px at 85% 15%, rgba(232,180,90,.14), transparent 70%);
  animation: drift 18s ease-in-out infinite alternate;
}
@keyframes drift { to { transform: translate3d(-30px, 20px, 0) scale(1.05); } }

/* ---------- Bars ---------- */
.topbar, .bottombar {
  position: fixed; left: 0; right: 0; z-index: 20;
  display: flex; align-items: center; justify-content: space-between;
  padding: 12px 24px;
  background: linear-gradient(to bottom, rgba(13,11,20,.85), rgba(13,11,20,.4));
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--glass-b);
}
.topbar { top: 0; }
.bottombar {
  bottom: 0; gap: 16px; justify-content: center;
  border-bottom: 0; border-top: 1px solid var(--glass-b);
  background: linear-gradient(to top, rgba(13,11,20,.9), rgba(13,11,20,.4));
}

.brand { display: flex; align-items: center; gap: 12px; }
.brand-mark {
  width: 40px; height: 40px; border-radius: 12px;
  display: grid; place-items: center; font-size: 22px;
  background: linear-gradient(135deg, var(--saffron), var(--gold));
  color: #2a1505; box-shadow: 0 6px 20px rgba(226,115,58,.4);
}
.brand h1 {
  font-family: 'Galada', 'Noto Serif Bengali', serif; font-weight: 400;
  font-size: 1.9rem; line-height: 1.3; letter-spacing: .5px; padding-top: 4px;
  filter: drop-shadow(0 2px 10px rgba(232,180,90,.35));
  background: linear-gradient(90deg, var(--gold-2), var(--gold));
  -webkit-background-clip: text; background-clip: text; color: transparent;
}

.top-actions { display: flex; gap: 8px; }

.icon-btn {
  width: 42px; height: 42px; border-radius: 12px;
  display: grid; place-items: center; cursor: pointer;
  background: var(--glass); border: 1px solid var(--glass-b); color: var(--text);
  transition: transform .2s, background .2s, border-color .2s, color .2s;
}
.icon-btn.small { width: 36px; height: 36px; border-radius: 10px; }
.icon-btn svg { width: 20px; height: 20px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.icon-btn:hover { background: rgba(232,180,90,.16); border-color: var(--gold); color: var(--gold-2); transform: translateY(-2px); }
.icon-btn.active { color: var(--gold); }
.icon-btn.muted { color: var(--muted); opacity: .6; }

/* ---------- Progress ---------- */
.progress { display: flex; align-items: center; gap: 18px; width: min(640px, 70vw); }
#slider {
  flex: 1; -webkit-appearance: none; appearance: none; height: 4px; border-radius: 4px;
  background: linear-gradient(90deg, var(--gold) var(--p, 0%), rgba(255,255,255,.15) var(--p, 0%));
  outline: none; cursor: pointer;
}
#slider::-webkit-slider-thumb {
  -webkit-appearance: none; width: 16px; height: 16px; border-radius: 50%;
  background: var(--gold-2); box-shadow: 0 0 0 4px rgba(232,180,90,.25); transition: transform .2s;
}
#slider::-webkit-slider-thumb:hover { transform: scale(1.25); }
#slider::-moz-range-thumb { width: 16px; height: 16px; border: 0; border-radius: 50%; background: var(--gold-2); }

.page-indicator { display: flex; align-items: center; gap: 6px; color: var(--muted); font-size: .95rem; white-space: nowrap; }
.page-indicator b { color: var(--text); font-weight: 600; }
#page-input {
  width: 56px; padding: 6px 8px; text-align: center; border-radius: 8px;
  background: var(--glass); border: 1px solid var(--glass-b); color: var(--text); font: inherit;
  -moz-appearance: textfield;
}
#page-input::-webkit-inner-spin-button { -webkit-appearance: none; }
#page-input:focus { outline: none; border-color: var(--gold); }

/* ---------- Stage & Book ---------- */
.stage {
  position: fixed; inset: 66px 0 62px 0;
  display: flex; align-items: center; justify-content: center;
}
.book-wrap {
  perspective: 2600px;
  transition: transform .6s cubic-bezier(.22,.8,.3,1);
}
.book {
  position: relative;
  transform-style: preserve-3d;
  filter: drop-shadow(0 30px 40px rgba(0,0,0,.55));
}
.book.single-mode .spine-shadow { display: none; }

.leaf {
  position: absolute; top: 0; width: 50%; height: 100%;
  transform-style: preserve-3d;
  transition: transform var(--flip-ms) cubic-bezier(.45,.05,.25,1);
}
.leaf.right-leaf { left: 50%; transform-origin: left center; }

.face {
  position: absolute; inset: 0; backface-visibility: hidden; -webkit-backface-visibility: hidden;
  background: #fbf8f2 center/cover no-repeat; overflow: hidden;
}
.face img { width: 100%; height: 100%; object-fit: cover; display: block; user-select: none; -webkit-user-drag: none; }
.face.back { transform: rotateY(180deg); }

/* gradients for page curvature */
.face.front::after, .face.back::after, .static-page::after {
  content: ''; position: absolute; inset: 0; pointer-events: none;
}
.face.front::after, .static-page.right::after { background: linear-gradient(90deg, rgba(0,0,0,.18), rgba(0,0,0,0) 7%, rgba(255,255,255,0) 90%, rgba(0,0,0,.05)); }
.face.back::after,  .static-page.left::after  { background: linear-gradient(270deg, rgba(0,0,0,.18), rgba(0,0,0,0) 7%, rgba(255,255,255,0) 90%, rgba(0,0,0,.05)); }

.static-page {
  position: absolute; top: 0; width: 50%; height: 100%; background: #fbf8f2; overflow: hidden;
}
.static-page img { width: 100%; height: 100%; object-fit: cover; display: block; user-select: none; -webkit-user-drag: none; }
.static-page.left { left: 0; }
.static-page.right { left: 50%; }
.static-page.empty { background: transparent; }
.static-page.empty::after { display: none; }

.leaf .shade {
  position: absolute; inset: 0; pointer-events: none; opacity: 0;
  background: linear-gradient(90deg, rgba(0,0,0,.35), transparent 60%);
  transition: opacity var(--flip-ms);
}
.leaf.flipping .shade { opacity: 1; }

.spine-shadow {
  position: absolute; top: 0; bottom: 0; left: 50%; width: 40px; transform: translateX(-50%);
  background: linear-gradient(90deg, transparent, rgba(0,0,0,.22) 45%, rgba(0,0,0,.28) 50%, rgba(0,0,0,.22) 55%, transparent);
  pointer-events: none; z-index: 50;
}

/* Single page (mobile) */
.book.single-mode .static-page.left,
.book.single-mode .static-page.right { left: 0; width: 100%; }
.book.single-mode .leaf { left: 0; width: 100%; }

.book .hotspot { position: absolute; top: 0; bottom: 0; width: 18%; z-index: 60; cursor: pointer; }
.book .hotspot.l { left: 0; } .book .hotspot.r { right: 0; }
.book .hotspot:hover { background: linear-gradient(90deg, rgba(232,180,90,.08), transparent); }
.book .hotspot.r:hover { background: linear-gradient(270deg, rgba(232,180,90,.08), transparent); }

/* cover-closed centering */
.book-wrap.at-start { transform: translateX(-25%); }
.book-wrap.at-end { transform: translateX(25%); }
.book.single-mode ~ * {}

/* ---------- Arrows ---------- */
.nav-arrow {
  position: absolute; top: 50%; transform: translateY(-50%); z-index: 15;
  width: 54px; height: 54px; border-radius: 50%; cursor: pointer;
  display: grid; place-items: center;
  background: var(--glass); border: 1px solid var(--glass-b); color: var(--text);
  backdrop-filter: blur(10px); transition: all .25s;
}
.nav-arrow svg { width: 24px; height: 24px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
.nav-arrow.left { left: 24px; } .nav-arrow.right { right: 24px; }
.nav-arrow:hover { background: linear-gradient(135deg, var(--saffron), var(--gold)); color: #2a1505; border-color: transparent; transform: translateY(-50%) scale(1.08); box-shadow: 0 10px 30px rgba(226,115,58,.45); }
.nav-arrow:disabled { opacity: .25; pointer-events: none; }

/* ---------- Loader ---------- */
.loader { position: absolute; inset: 0; display: grid; place-content: center; gap: 18px; text-align: center; z-index: 30; color: var(--muted); transition: opacity .5s; }
.loader.hidden { opacity: 0; pointer-events: none; }
.spinner { width: 54px; height: 54px; margin: 0 auto; border-radius: 50%; border: 3px solid rgba(232,180,90,.2); border-top-color: var(--gold); animation: spin 1s linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }

/* ---------- Thumbnails ---------- */
.thumbs-panel {
  position: fixed; top: 0; right: 0; bottom: 0; width: min(380px, 90vw); z-index: 40;
  background: rgba(20,16,28,.92); backdrop-filter: blur(20px);
  border-left: 1px solid var(--glass-b);
  transform: translateX(100%); transition: transform .45s cubic-bezier(.22,.8,.3,1);
  display: flex; flex-direction: column;
}
.thumbs-panel.open { transform: none; box-shadow: -20px 0 60px rgba(0,0,0,.5); }
.thumbs-head { display: flex; justify-content: space-between; align-items: center; padding: 18px 20px; border-bottom: 1px solid var(--glass-b); }
.thumbs-head h2 { font-family: 'Playfair Display', serif; color: var(--gold-2); font-size: 1.25rem; }
.thumbs-grid { flex: 1; overflow-y: auto; padding: 16px; display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.thumb { cursor: pointer; text-align: center; font-size: .78rem; color: var(--muted); }
.thumb img { width: 100%; aspect-ratio: 381 / 598; object-fit: cover; border-radius: 6px; border: 2px solid transparent; background: #2a2433; transition: transform .2s, border-color .2s; }
.thumb:hover img { transform: translateY(-3px); border-color: rgba(232,180,90,.5); }
.thumb.current img { border-color: var(--gold); box-shadow: 0 0 0 3px rgba(232,180,90,.25); }
.thumb.current { color: var(--gold-2); }
.thumbs-grid::-webkit-scrollbar { width: 6px; }
.thumbs-grid::-webkit-scrollbar-thumb { background: rgba(232,180,90,.3); border-radius: 6px; }

/* ---------- Zoom ---------- */
.zoom-view {
  position: fixed; inset: 0; z-index: 50; background: rgba(8,6,12,.96);
  opacity: 0; pointer-events: none; transition: opacity .3s; overflow: auto; cursor: grab;
}
.zoom-view.open { opacity: 1; pointer-events: auto; }
.zoom-view.dragging { cursor: grabbing; }
.zoom-inner { display: flex; justify-content: center; gap: 0; padding: 40px; min-width: max-content; }
.zoom-inner img { height: 180vh; display: block; user-select: none; -webkit-user-drag: none; }
.zoom-close { position: fixed; top: 18px; right: 18px; }
.zoom-hint { position: fixed; bottom: 18px; left: 50%; transform: translateX(-50%); color: var(--muted); font-size: .85rem; background: var(--glass); padding: 6px 14px; border-radius: 20px; }

/* ---------- Responsive ---------- */
@media (max-width: 760px) {
  .topbar { padding: 10px 14px; }
  .brand h1 { font-size: 1.2rem; }
  .icon-btn { width: 38px; height: 38px; }
  .top-actions { gap: 6px; }
  #btn-sound { display: none; }
  .nav-arrow { width: 42px; height: 42px; }
  .nav-arrow.left { left: 6px; } .nav-arrow.right { right: 6px; }
  .progress { width: 100%; gap: 10px; }
  .bottombar { padding: 10px 12px; gap: 8px; }
  .book-wrap.at-start, .book-wrap.at-end { transform: none; }
}