.book-tile {
      border: 1px solid #ddd;
      border-radius: 12px;
      padding: 1.25rem;
      margin-bottom: 1rem;
      background: #f9f9f9;
      cursor: pointer;
      transition: background 0.2s;
    }
    .book-tile:hover {
      background: #eef5ff;
    }
    .book-detail {
      display: none;
      margin-top: 0.75rem;
      padding-left: 1rem;
    }

.book-cover {
  max-width: 69px;
  max-height: 104px;
  object-fit: cover;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

@media (max-width: 767.98px) {
  .book-cover {
    margin-bottom: 1rem;
  }
}

/* Lightbox background */
.books-lightbox-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(25, 25, 112, 0.3);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  opacity: 0;
  pointer-events: none;
  transition: opacity 1.25s ease;
  backdrop-filter: blur(1px);
}

.books-lightbox-overlay.visible {
  opacity: 1;
  pointer-events: auto;
}

/* Enlarged image */
.books-lightbox-overlay img {
  max-width: 90%;
  max-height: 90%;
  border-radius: 8px;
  box-shadow: 0 0 20px rgba(0,0,0,0.5);
  cursor: zoom-out;
}