.transform-style-preserve-3d {
  transform-style: preserve-3d;
}
.backface-hidden {
  backface-visibility: hidden;
}
.transform-rotate-y-180 {
  transform: rotateY(180deg);
}

/* Thumbnail Container */
.thumb-box {
  width: 100%;
  height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: white;
  border-radius: 8px;
  padding: 4px;
  box-shadow: 0 1px 4px rgba(0,0,0,0.1);
  transition: all 0.3s;
  cursor: pointer;
}
.thumb-box img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}
.thumb-box:hover {
  transform: scale(1.05);
}

/* Active Thumbnail Style */
.swiper-slide.active .thumb-box {
  border: 2px solid #3B82F6;
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.3);
}

/* Swiper Styles */
.book-thumbnails {
  padding: 0 10px;
}

/* Mobile (default) */
.book-thumbnails .swiper-slide {
  width: 25%;
  flex-shrink: 0;
  opacity: 0.8;
  transition: opacity 0.3s;
  padding: 0 4px;
  box-sizing: border-box;
}

/* Perbaikan Spacing untuk Mobile */
@media (max-width: 639px) {
  .max-w-lg.order-last {
    margin-top: 2rem !important;
    padding-top: 1.5rem;
    padding-bottom: 1.5rem;
  }
  
  .relative.w-full {
    margin-bottom: 1.5rem !important;
  }
  
  .book-thumbnails {
    margin-top: 1rem !important;
  }
}

/* Tablet (640px - 1023px) */
@media (min-width: 640px) and (max-width: 1023px) {
  /* Style Thumbnail */
  .book-thumbnails {
    padding: 0 20px;
  }
  .thumb-box {
    height: 100px;
  }
  .book-thumbnails .swiper-slide {
    width: 20%;
  }
  
  /* Navigation */
  .swiper-pagination {
    display: none !important;
  }
  .swiper-button-prev,
  .swiper-button-next {
    display: flex !important;
    width: 32px;
    height: 32px;
    --swiper-navigation-size: 16px;
  }
  
  /* Spacing Khusus Tablet */
  .max-w-lg.order-last {
    margin-top: 2.5rem !important;
    padding-top: 2rem;
    padding-bottom: 2rem;
  }
  .relative.w-full {
    margin-bottom: 2rem !important;
  }
}

/* Desktop (1024px ke atas) */
@media (min-width: 1024px) {
  .book-thumbnails {
    padding: 0 40px;
  }
  .thumb-box {
    height: 120px;
  }
  .book-thumbnails .swiper-slide {
    width: 90px;
  }
}

/* Navigation buttons */
.book-thumbnails .swiper-button-prev,
.book-thumbnails .swiper-button-next {
  background: white;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
  color: #4b5563;
  --swiper-navigation-size: 14px;
  display: none;
}

/* Pagination */
.book-thumbnails .swiper-pagination {
  position: relative !important;
  margin-top: 1rem !important;
}
.book-thumbnails .swiper-pagination-bullet {
  width: 8px;
  height: 8px;
  background: #d1d5db;
  opacity: 1;
}
.book-thumbnails .swiper-pagination-bullet-active {
  background: #4b5563;
}