/* Preloader: book/page-flip loader (Academira style) */
.loader-book {
  position: relative;
  width: 74px;
  height: 54px;
  transform: translateZ(0);
}

.loader-book__cover {
  position: absolute;
  inset: 0;
  border: 4px solid hsl(var(--white));
  border-radius: 10px;
  opacity: 0.9;
}

/* Spine */
.loader-book__cover::before {
  content: "";
  position: absolute;
  top: 6px;
  bottom: 6px;
  left: 10px;
  width: 4px;
  border-radius: 3px;
  background: hsl(var(--white) / 0.9);
}

.loader-book__page {
  position: absolute;
  top: 8px;
  bottom: 8px;
  left: 18px;
  width: 24px;
  border-radius: 4px;
  background: hsl(var(--white));
  transform-origin: left center;
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.18);
  animation: academiraPageFlip 1.2s infinite ease-in-out;
}

.loader-book__page--1 {
  opacity: 0.95;
  animation-delay: 0s;
}

.loader-book__page--2 {
  opacity: 0.7;
  animation-delay: 0.15s;
}

.loader-book__page--3 {
  opacity: 0.5;
  animation-delay: 0.3s;
}

@keyframes academiraPageFlip {
  0% {
    transform: rotateY(0deg) translateX(0);
  }
  35% {
    transform: rotateY(-85deg) translateX(2px);
  }
  70% {
    transform: rotateY(-180deg) translateX(6px);
  }
  100% {
    transform: rotateY(-180deg) translateX(6px);
  }
}