.back-to-top {
    opacity: 0;
    transform: translateY(40px);
    pointer-events: none;
    transition: opacity 0.35s ease, transform 0.35s ease;
  }

  .back-to-top.is-visible {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
  }
  

.book-hover {
  position: relative;
  display: inline-block;
  overflow: visible;
}

.book-shadow {
  position: absolute;
  left: 0;
  top: 0;
  z-index: 1;
  width: 100%;
  display: block;
  opacity: 0.7;
  transition: opacity 0.3s ease-out;
}

.book-img {
  position: relative;
  z-index: 2;
  width: 100%;
  display: block;
  transform: translateY(0);
  transition: transform 0.3s ease-out;
}

.book-arrow {
  pointer-events: none;
  position: absolute;
  left: 69%;
  top: 75%;
  z-index: 99;

  width: 12%;
  aspect-ratio: 1 / 1;

  display: flex;
  align-items: center;
  justify-content: center;

  border-radius: 9999px;
  background: rgba(255, 255, 255, 0.33);
  color: white;

  opacity: 0;
  transform: translate(-50%, 8px);
  transition: transform 0.3s ease-out, opacity 0.3s ease-out;
}

.book-hover:hover .book-img {
  transform: translateY(-16px);
}

.book-hover:hover .book-shadow {
  opacity: 0.45;
}

.book-hover:hover .book-arrow {
  opacity: 1;
  transform: translate(-50%, 0);
}