.ne-pdfbook{
  background: var(--ne-bg);
  color: #fff;
  border-radius: 16px;
  padding: 14px;
  margin: 18px auto;
  box-shadow: 0 12px 40px rgba(0,0,0,.25);
  position: relative;
}

.ne-pdfbook *{ box-sizing: border-box; }

.ne-pdfbook-toolbar{
  display:flex;
  align-items:center;
  justify-content: space-between;
  gap: 10px;
  padding: 8px 10px;
  border-radius: 12px;
  background: rgba(255,255,255,.08);
  border: 1px solid rgba(255,255,255,.12);
}

.ne-btn{
  appearance: none;
  border: 0;
  padding: 10px 14px;
  border-radius: 12px;
  cursor: pointer;
  background: var(--ne-accent);
  color:#111827;
  font-weight: 700;
  line-height: 1;
}

.ne-btn[disabled]{
  opacity:.45;
  cursor:not-allowed;
}

.ne-indicator{
  font-weight: 600;
  opacity: .95;
  padding: 6px 10px;
  border-radius: 10px;
  background: rgba(0,0,0,.18);
}

.ne-pdfbook-stage{
  position: relative;
  margin-top: 12px;
  border-radius: 16px;
  overflow: hidden;
  min-height: 420px;
  background: rgba(255,255,255,.04);
  border: 1px solid rgba(255,255,255,.12);
}

.ne-spread-under{
  display:flex;
  width: 100%;
  height: 100%;
  min-height: 420px;
}

.ne-page{
  width: 50%;
  background: var(--ne-page);
  position: relative;
}

.ne-page img{
  width: 100%;
  height: 100%;
  object-fit: contain;
  display:block;
  background: var(--ne-page);
}

.ne-left{
  border-right: 1px solid rgba(0,0,0,.08);
}

.ne-right{
  border-left: 1px solid rgba(0,0,0,.08);
}

.ne-pdfbook-stage::before{
  content:"";
  position:absolute;
  top:0;
  left:50%;
  width: 20px;
  height: 100%;
  transform: translateX(-50%);
  background: rgba(0,0,0,.12);
  filter: blur(10px);
  pointer-events: none;
  opacity: .55;
  z-index: 2;
}

.ne-mode-single .ne-spread-under{ display:block; }
.ne-mode-single .ne-page{ width:100%; }
.ne-mode-single .ne-right{ display:none; }
.ne-mode-single .ne-pdfbook-stage::before{ display:none; }

.ne-turn{
  position:absolute;
  top:0;
  height:100%;
  width:50%;
  z-index: 5;
  transform-style: preserve-3d;
  perspective: 1600px;
}

.ne-mode-single .ne-turn{ width:100%; }

.ne-turn-next{ right:0; transform-origin: left center; }
.ne-turn-prev{ left:0; transform-origin: right center; }

.ne-turn-face{
  position:absolute;
  inset:0;
  backface-visibility: hidden;
  overflow:hidden;
  background: var(--ne-page);
  box-shadow: 0 10px 35px rgba(0,0,0,.25);
}

.ne-turn-face img{
  width:100%;
  height:100%;
  object-fit: contain;
  display:block;
  background: var(--ne-page);
}

.ne-turn-back{
  transform: rotateY(180deg);
}

.ne-turn-next.ne-anim{
  animation: neFlipNext 520ms ease-in-out forwards;
}

.ne-turn-prev.ne-anim{
  animation: neFlipPrev 520ms ease-in-out forwards;
}

@keyframes neFlipNext{
  from { transform: rotateY(0deg); }
  to   { transform: rotateY(-180deg); }
}

@keyframes neFlipPrev{
  from { transform: rotateY(0deg); }
  to   { transform: rotateY(180deg); }
}

.ne-pdfbook.ne-busy .ne-btn{ pointer-events:none; }

.ne-pdfbook-error{
  padding: 14px;
  border-radius: 12px;
  background: #fee2e2;
  border: 1px solid #fecaca;
  color: #7f1d1d;
  max-width: 980px;
  margin: 18px auto;
}