/* ==========================================================================
   BO2K — Component System (Physical Book Aesthetics & Editorial Detail)
   ========================================================================== */

/* ==========================================================================
   1. BOOK COVER COMPONENT (Tactile Paper / Cloth Feel)
   ========================================================================== */
.book-cover {
  position: relative;
  aspect-ratio: 2 / 3;
  width: 100%;
  border-radius: var(--radius-sm);
  background-color: var(--cover-bg, #201F1D);
  color: var(--cover-text, #F8F5EE);
  box-shadow: var(--shadow-book);
  padding: 1.25rem 1rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  overflow: hidden;
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
  user-select: none;
}

/* Subtle physical book spine ridge and lighting gradient */
.book-cover::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  width: 14px;
  background: linear-gradient(
    90deg,
    rgba(255, 255, 255, 0.08) 0%,
    rgba(0, 0, 0, 0.18) 40%,
    rgba(255, 255, 255, 0.05) 70%,
    rgba(0, 0, 0, 0.25) 100%
  );
  border-right: 1px solid rgba(0, 0, 0, 0.25);
  pointer-events: none;
}

/* Subtle book deboss border line */
.book-cover::after {
  content: '';
  position: absolute;
  top: 8px;
  bottom: 8px;
  left: 20px;
  right: 8px;
  border: 1px solid rgba(255, 255, 255, 0.1);
  pointer-events: none;
  border-radius: 1px;
}

.book-cover:hover {
  transform: translateY(-4px) rotate(-0.5deg);
  box-shadow: var(--shadow-book-raised);
}

.cover-header {
  position: relative;
  z-index: 2;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
}

.cover-monogram {
  font-family: var(--font-sans);
  font-size: 0.625rem;
  letter-spacing: 0.18em;
  font-weight: 700;
  opacity: 0.75;
}

.cover-cat-pill {
  font-size: 0.5625rem;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  padding: 0.2rem 0.45rem;
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: var(--radius-sm);
  opacity: 0.8;
}

.cover-body {
  position: relative;
  z-index: 2;
  margin: auto 0;
  padding: 0.5rem 0;
}

.cover-title-placeholder {
  font-family: var(--font-serif);
  font-size: 1.125rem;
  line-height: 1.25;
  letter-spacing: 0.02em;
  font-weight: 500;
  color: var(--cover-text, #F8F5EE);
  margin-bottom: 0.4rem;
}

.cover-subtitle-placeholder {
  font-family: var(--font-sans);
  font-size: 0.6875rem;
  line-height: 1.35;
  color: var(--cover-text, #F8F5EE);
  opacity: 0.75;
}

.cover-footer {
  position: relative;
  z-index: 2;
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  border-top: 1px solid rgba(255, 255, 255, 0.12);
  padding-top: 0.625rem;
}

.cover-author-placeholder {
  font-family: var(--font-sans);
  font-size: 0.6875rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  font-weight: 600;
  opacity: 0.85;
}

.cover-bo2k-mark {
  font-family: var(--font-serif);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  opacity: 0.6;
}

/* Small thumbnail variant for list items */
.book-cover.thumb {
  width: 58px;
  height: 82px;
  padding: 0.5rem 0.35rem;
  flex-shrink: 0;
  box-shadow: 0 2px 6px rgba(17, 17, 15, 0.08);
}

.book-cover.thumb::before {
  width: 6px;
}

.book-cover.thumb::after {
  display: none;
}

.book-cover.thumb .cover-monogram {
  font-size: 0.5rem;
}

.book-cover.thumb .cover-body,
.book-cover.thumb .cover-footer,
.book-cover.thumb .cover-cat-pill {
  display: none;
}

.book-cover.thumb .thumb-title-brief {
  font-family: var(--font-serif);
  font-size: 0.625rem;
  line-height: 1.15;
  color: var(--cover-text, #F8F5EE);
  opacity: 0.9;
  overflow: hidden;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
}

/* ==========================================================================
   2. HERO VISUAL BOOK COMPOSITION (Photographic Editorial Composition)
   ========================================================================== */
.hero-book-stage {
  position: relative;
  width: 100%;
  max-width: 380px;
  height: 380px;
  margin: 0 auto;
}

.stage-book-back {
  position: absolute;
  top: 30px;
  right: 15px;
  width: 210px;
  aspect-ratio: 2 / 3;
  background-color: #3D2B24;
  color: #F8F5EE;
  border-radius: var(--radius-sm);
  box-shadow: -10px 20px 40px rgba(17, 17, 15, 0.12);
  transform: rotate(6deg);
  opacity: 0.85;
  padding: 1.25rem 1rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: transform 600ms cubic-bezier(0.16, 1, 0.3, 1);
}

.stage-book-back::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 12px;
  background: linear-gradient(90deg, rgba(255,255,255,0.06), rgba(0,0,0,0.2));
}

.stage-book-front {
  position: absolute;
  top: 60px;
  left: 25px;
  width: 230px;
  aspect-ratio: 2 / 3;
  background-color: #201F1D;
  color: #F8F5EE;
  border-radius: var(--radius-sm);
  box-shadow: 10px 25px 50px rgba(17, 17, 15, 0.18), 0 2px 8px rgba(17, 17, 15, 0.08);
  transform: rotate(-3deg);
  padding: 1.5rem 1.25rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: transform 600ms cubic-bezier(0.16, 1, 0.3, 1);
}

.hero-book-stage:hover .stage-book-front {
  transform: rotate(-1deg) translateY(-8px);
}

.hero-book-stage:hover .stage-book-back {
  transform: rotate(8deg) translateY(-4px);
}

.stage-plate {
  position: absolute;
  bottom: 10px;
  left: 10px;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  padding: 0.625rem 1rem;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 0.6875rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  box-shadow: var(--shadow-subtle);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.stage-plate-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--accent-leather);
}

/* ==========================================================================
   3. CATEGORY PILL COMPONENT
   ========================================================================== */
.category-pill {
  display: inline-flex;
  align-items: center;
  padding: 0.45rem 1.125rem;
  font-size: 0.8125rem;
  font-weight: 500;
  letter-spacing: 0.03em;
  color: var(--text-secondary);
  background-color: transparent;
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-pill);
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.category-pill:hover {
  border-color: var(--text-primary);
  color: var(--text-primary);
  background-color: var(--bg-surface);
}

.category-pill.active {
  background-color: var(--text-primary);
  border-color: var(--text-primary);
  color: var(--bg-primary);
}

/* ==========================================================================
   4. FEATURED BOOK MAGAZINE SPOTLIGHT
   ========================================================================== */
.featured-magazine-box {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 1.5rem;
  margin-bottom: 3.5rem;
  position: relative;
  overflow: hidden;
  transition: border-color var(--transition-normal);
}

@media (min-width: 840px) {
  .featured-magazine-box {
    padding: 3rem;
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: 3.5rem;
    align-items: center;
  }
}

.featured-magazine-box:hover {
  border-color: rgba(17, 17, 15, 0.35);
}

.featured-badge {
  font-family: var(--font-sans);
  font-size: 0.6875rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  font-weight: 600;
  color: var(--accent-leather);
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.featured-badge::after {
  content: '';
  flex: 1;
  height: 1px;
  background-color: var(--border-subtle);
}

.featured-cover-wrap {
  max-width: 240px;
  margin: 0 auto 1.75rem;
}

@media (min-width: 840px) {
  .featured-cover-wrap {
    margin: 0;
    max-width: 100%;
  }
}

.featured-info {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.featured-cat-meta {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
}

.featured-title {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 500;
  line-height: 1.15;
  color: var(--text-primary);
}

.featured-author {
  font-family: var(--font-sans);
  font-size: 0.875rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-secondary);
  font-weight: 500;
}

.featured-desc {
  font-size: 0.9375rem;
  line-height: 1.65;
  color: var(--text-secondary);
  max-width: 540px;
}

.featured-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-top: 0.5rem;
}

/* ==========================================================================
   5. EDITORIAL VERTICAL ARCHIVE LIST
   ========================================================================== */
.archive-list {
  display: flex;
  flex-direction: column;
  border-top: 1px solid var(--border-subtle);
}

.archive-row-item {
  display: grid;
  grid-template-columns: 36px 58px 1fr 32px;
  gap: 1rem;
  align-items: center;
  padding: 1.25rem 0;
  border-bottom: 1px solid var(--border-subtle);
  transition: background-color var(--transition-fast), padding-left var(--transition-fast);
  cursor: pointer;
}

@media (min-width: 768px) {
  .archive-row-item {
    grid-template-columns: 48px 64px 1.5fr 1fr 120px 40px;
    gap: 1.5rem;
    padding: 1.5rem 0.5rem;
  }
}

.archive-row-item:hover {
  background-color: rgba(52, 51, 47, 0.02);
  padding-left: 0.5rem;
}

.archive-index-num {
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-faint);
  letter-spacing: 0.05em;
}

.archive-main-info {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.archive-row-title {
  font-family: var(--font-serif);
  font-size: 1.125rem;
  font-weight: 500;
  line-height: 1.25;
  color: var(--text-primary);
}

.archive-row-subtitle {
  font-size: 0.75rem;
  color: var(--text-muted);
  display: none;
}

@media (min-width: 640px) {
  .archive-row-subtitle {
    display: block;
  }
}

.archive-author-col {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-secondary);
}

.archive-meta-col {
  display: none;
  font-size: 0.75rem;
  color: var(--text-muted);
}

@media (min-width: 768px) {
  .archive-meta-col {
    display: flex;
    flex-direction: column;
    gap: 0.2rem;
  }
}

.archive-open-arrow {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  color: var(--text-muted);
  transition: transform var(--transition-fast), color var(--transition-fast);
}

.archive-row-item:hover .archive-open-arrow {
  transform: translateX(3px);
  color: var(--text-primary);
}

/* ==========================================================================
   6. FULLSCREEN SEARCH INTERFACE
   ========================================================================== */
.search-modal-backdrop {
  position: fixed;
  inset: 0;
  z-index: 200;
  background-color: rgba(248, 245, 238, 0.98);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  display: flex;
  flex-direction: column;
  padding: 1.25rem;
  animation: searchFadeIn 240ms cubic-bezier(0.16, 1, 0.3, 1) forwards;
  overflow-y: auto;
}

@keyframes searchFadeIn {
  from {
    opacity: 0;
    transform: translateY(-8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.search-modal-container {
  width: 100%;
  max-width: 720px;
  margin: 0 auto;
  padding: 1rem 0 3rem;
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.search-header-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--border-subtle);
  padding-bottom: 0.75rem;
}

.search-input-field {
  width: 100%;
  font-family: var(--font-serif);
  font-size: clamp(1.35rem, 3.5vw, 2.15rem);
  color: var(--text-primary);
  background: transparent;
}

.search-input-field::placeholder {
  color: var(--text-faint);
  font-style: italic;
}

.search-close-btn {
  padding: 0.5rem;
  color: var(--text-muted);
  font-size: 0.8125rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  transition: color var(--transition-fast);
}

.search-close-btn:hover {
  color: var(--text-primary);
}

.search-section {
  display: flex;
  flex-direction: column;
  gap: 0.875rem;
}

.search-section-label {
  font-size: 0.6875rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--text-muted);
  font-weight: 600;
}

.chip-cluster {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.search-topic-chip {
  font-size: 0.8125rem;
  padding: 0.35rem 0.875rem;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  transition: all var(--transition-fast);
  cursor: pointer;
}

.search-topic-chip:hover {
  border-color: var(--text-primary);
  color: var(--text-primary);
}

/* ==========================================================================
   7. HOW IT WORKS MODAL / SHEET
   ========================================================================== */
.modal-backdrop {
  position: fixed;
  inset: 0;
  z-index: 150;
  background-color: rgba(17, 17, 15, 0.45);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: flex-end;
  justify-content: center;
  animation: modalFadeIn 220ms ease forwards;
}

@media (min-width: 640px) {
  .modal-backdrop {
    align-items: center;
    padding: 1.5rem;
  }
}

@keyframes modalFadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.modal-sheet {
  background-color: var(--bg-primary);
  width: 100%;
  max-width: 640px;
  max-height: 88vh;
  overflow-y: auto;
  border-top-left-radius: var(--radius-md);
  border-top-right-radius: var(--radius-md);
  padding: 2rem 1.5rem 3rem;
  box-shadow: 0 -10px 40px rgba(17, 17, 15, 0.15);
  border: 1px solid var(--border-subtle);
}

@media (min-width: 640px) {
  .modal-sheet {
    border-radius: var(--radius-sm);
    padding: 2.5rem;
  }
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.25rem;
  border-bottom: 1px solid var(--border-subtle);
  padding-bottom: 1rem;
}

.modal-brand-seal {
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 1.25rem 0 1.5rem;
  margin-bottom: 1rem;
  border-bottom: 1px solid var(--border-subtle);
}

.modal-brand-logo-img {
  height: 64px;
  width: auto;
  max-width: 100%;
  display: block;
  object-fit: contain;
  transition: filter var(--transition-normal);
}

[data-theme="midnight"] .modal-brand-logo-img {
  filter: brightness(0) invert(0.95);
}

/* ==========================================================================
   8. ARCHITECTURAL EMPTY STATES
   ========================================================================== */
.empty-state-box {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 4.5rem 1.5rem;
  border: 1px dashed var(--border-subtle);
  border-radius: var(--radius-sm);
  background-color: rgba(242, 238, 229, 0.4);
  margin: 2rem 0;
}

.empty-state-mark {
  width: 48px;
  height: 48px;
  margin-bottom: 1.25rem;
  color: var(--text-faint);
  stroke-width: 1.2;
}

.empty-state-title {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.empty-state-subtext {
  font-size: 0.875rem;
  color: var(--text-muted);
  max-width: 320px;
  line-height: 1.6;
  margin-bottom: 1.75rem;
}

/* ==========================================================================
   9. CLEAN COMPACT BOOK GRID (2 Books per row on mobile)
   ========================================================================== */
.library-header-compact {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  margin-bottom: 1.5rem;
}

.library-title-main {
  font-family: var(--font-serif);
  font-size: clamp(2.25rem, 5vw, 3rem);
  font-weight: 500;
  line-height: 1.1;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.library-sub-compact {
  font-size: 0.9375rem;
  color: var(--text-muted);
  line-height: 1.5;
}

/* Compact Search Bar */
.library-search-compact-wrap {
  position: relative;
  display: flex;
  align-items: center;
  margin-top: 1rem;
  max-width: 440px;
}

.library-search-compact-wrap svg {
  position: absolute;
  left: 0.875rem;
  width: 16px;
  height: 16px;
  color: var(--text-muted);
  pointer-events: none;
}

.library-search-compact-input {
  width: 100%;
  padding: 0.625rem 0.875rem 0.625rem 2.35rem;
  font-family: var(--font-sans);
  font-size: 0.875rem;
  color: var(--text-primary);
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.library-search-compact-input:focus {
  border-color: var(--text-primary);
  background-color: #FFFFFF;
}

.library-search-compact-input::placeholder {
  color: var(--text-muted);
}

/* Categories Bar Compact */
.categories-compact-bar {
  margin: 1.25rem 0 2rem;
  overflow-x: auto;
  scrollbar-width: none;
  -ms-overflow-style: none;
  -webkit-overflow-scrolling: touch;
}

.categories-compact-bar::-webkit-scrollbar {
  display: none;
}

.categories-compact-list {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  min-width: max-content;
  list-style: none;
}

.category-pill-compact {
  display: inline-flex;
  align-items: center;
  padding: 0.35rem 0.875rem;
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  color: var(--text-secondary);
  background-color: transparent;
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-pill);
  transition: all var(--transition-fast);
  white-space: nowrap;
  cursor: pointer;
}

.category-pill-compact:hover {
  border-color: var(--text-primary);
  color: var(--text-primary);
  background-color: var(--bg-surface);
}

.category-pill-compact.active {
  background-color: var(--text-primary);
  border-color: var(--text-primary);
  color: var(--bg-primary);
}

/* The Book Grid: 2 per row on Mobile, 3 on Tablet, 4-5 on Desktop */
.book-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem 0.875rem;
  margin-bottom: 3.5rem;
}

@media (min-width: 640px) {
  .book-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem 1.25rem;
  }
}

@media (min-width: 960px) {
  .book-grid {
    grid-template-columns: repeat(4, 1fr);
    gap: 2.25rem 1.5rem;
  }
}

@media (min-width: 1200px) {
  .book-grid {
    grid-template-columns: repeat(5, 1fr);
    gap: 2.5rem 1.75rem;
  }
}

/* ==========================================================================
   10. TACTILE 3D BOOKSHELF CARDS (Ultra-Smooth 120fps Library Extraction)
   ========================================================================== */

.book-grid-card {
  display: flex;
  flex-direction: column;
  cursor: pointer;
  user-select: none;
  outline: none;
  position: relative;
  perspective: 800px;
  -webkit-tap-highlight-color: transparent;
}

.book-grid-cover-wrap {
  position: relative;
  width: 100%;
  aspect-ratio: 2 / 3;
  border-radius: 4px 7px 7px 4px;
  overflow: hidden;
  background-color: var(--bg-surface);
  box-shadow: 0 4px 12px rgba(17, 17, 15, 0.08), 0 1px 3px rgba(17, 17, 15, 0.04);
  /* GPU hardware layer promotion */
  transform: translate3d(0, 0, 0);
  transform-origin: center bottom;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  transition: transform 260ms cubic-bezier(0.2, 0.9, 0.3, 1), box-shadow 260ms cubic-bezier(0.2, 0.9, 0.3, 1);
}

/* Tactile Bookshelf Pull: Swift, responsive 3D lift & tilt (zero jank) */
.book-grid-card:hover .book-grid-cover-wrap,
.book-grid-card:focus-visible .book-grid-cover-wrap {
  transform: translate3d(0, -10px, 0) rotateY(-7.5deg) rotateX(3deg) scale(1.028);
  box-shadow: -10px 18px 28px -4px rgba(17, 17, 15, 0.22), 0 4px 10px rgba(17, 17, 15, 0.08);
  z-index: 3;
}

/* Instant click compression */
.book-grid-card:active .book-grid-cover-wrap {
  transform: translate3d(0, -4px, 0) rotateY(-3deg) scale(0.99);
  transition-duration: 90ms;
}

/* Spine Hinge Crease on the left edge (Clean RGBA alpha, NO mix-blend-mode overhead) */
.book-spine-crease {
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  width: 18px;
  z-index: 4;
  pointer-events: none;
  border-radius: 4px 0 0 4px;
  background: linear-gradient(
    90deg, 
    rgba(0, 0, 0, 0.3) 0%, 
    rgba(255, 255, 255, 0.2) 20%, 
    rgba(0, 0, 0, 0.12) 35%, 
    transparent 100%
  );
  border-right: 1px solid rgba(0, 0, 0, 0.08);
}

[data-theme="midnight"] .book-spine-crease {
  background: linear-gradient(
    90deg, 
    rgba(0, 0, 0, 0.45) 0%, 
    rgba(255, 255, 255, 0.25) 20%, 
    rgba(0, 0, 0, 0.2) 35%, 
    transparent 100%
  );
}

/* Fore-Edge Deckle Stacked Pages along the right side (GPU static, moves with parent) */
.book-page-edge {
  position: absolute;
  top: 2px;
  right: 0;
  bottom: 2px;
  width: 5px;
  z-index: 3;
  pointer-events: none;
  border-radius: 0 3px 3px 0;
  background: repeating-linear-gradient(
    to bottom, 
    #F4EFE6 0px, 
    #F4EFE6 2px, 
    #DCD4C3 3px, 
    #F4EFE6 4px
  );
  box-shadow: inset 1px 0 2px rgba(0, 0, 0, 0.2);
}

/* Silky Light Sheen (Optimized GPU translate3d with matched 280ms duration) */
.book-shelf-sheen {
  position: absolute;
  inset: 0;
  z-index: 5;
  pointer-events: none;
  border-radius: inherit;
  background: linear-gradient(
    115deg, 
    transparent 20%, 
    rgba(255, 255, 255, 0.0) 38%, 
    rgba(255, 255, 255, 0.32) 50%, 
    rgba(255, 255, 255, 0.0) 62%, 
    transparent 80%
  );
  opacity: 0;
  transform: translate3d(-100%, 0, 0);
  transition: transform 320ms cubic-bezier(0.2, 0.8, 0.2, 1), opacity 240ms ease;
}

.book-grid-card:hover .book-shelf-sheen {
  opacity: 1;
  transform: translate3d(100%, 0, 0);
}

.book-grid-cover-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  pointer-events: none;
}

.book-grid-info {
  margin-top: 0.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  pointer-events: none;
}

.book-grid-title {
  font-family: var(--font-serif);
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.25;
  color: var(--text-primary);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  transition: color 200ms ease;
}

.book-grid-card:hover .book-grid-title {
  color: var(--accent);
}

.book-grid-author {
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  color: var(--text-muted);
  line-height: 1.3;
  display: -webkit-box;
  -webkit-line-clamp: 1;
  -webkit-box-orient: vertical;
  overflow: hidden;
  transition: color 200ms ease;
}

.book-grid-card:hover .book-grid-author {
  color: var(--text-secondary);
}

/* Empty State / Notice for Library Grid */
.empty-library-notice {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  padding: 2.25rem 1.5rem;
  border-radius: var(--radius-sm);
  text-align: center;
  margin: 1.5rem 0 3rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.75rem;
}

.empty-library-notice-title {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  color: var(--text-primary);
  font-weight: 500;
}

.empty-library-notice-sub {
  font-size: 0.875rem;
  color: var(--text-muted);
  max-width: 380px;
  line-height: 1.5;
}

/* ==========================================================================
   11. 3D BOOK OPENING CINEMATIC STAGE & PAGE TURN ANIMATION
   ========================================================================== */

.book-open-stage-backdrop {
  position: fixed;
  inset: 0;
  z-index: 100000;
  display: flex;
  align-items: center;
  justify-content: center;
  background: radial-gradient(circle at 50% 48%, rgba(18, 17, 15, 0.94), rgba(6, 6, 5, 0.98));
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  opacity: 0;
  pointer-events: none;
  cursor: pointer;
  transition: opacity 280ms cubic-bezier(0.16, 1, 0.3, 1);
  overflow: hidden;
}

.book-open-stage-backdrop.is-active {
  opacity: 1;
  pointer-events: auto;
}

.book-open-stage-backdrop.is-dissolving {
  opacity: 0;
  pointer-events: none;
  transition: opacity 260ms ease-out;
}

/* Atmospheric Library Spotlight */
.book-open-spotlight {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: radial-gradient(ellipse 65% 55% at 50% 42%, rgba(255, 245, 225, 0.14) 0%, rgba(210, 185, 145, 0.05) 50%, transparent 75%);
  animation: spotlightPulse 3s ease-in-out infinite alternate;
}

@keyframes spotlightPulse {
  0% { opacity: 0.85; }
  100% { opacity: 1; }
}

/* 3D Viewport with deep perspective */
.book-open-viewport {
  position: relative;
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  perspective: 2000px;
  perspective-origin: 50% 50%;
  pointer-events: none;
}

/* 3D Assembly Container */
.book-3d-assembly {
  position: relative;
  width: min(320px, 80vw);
  height: min(470px, 116vw);
  transform-style: preserve-3d;
  pointer-events: auto;
  animation: stageBookEntrance 920ms cubic-bezier(0.2, 0.9, 0.3, 1) forwards;
  will-change: transform;
}

@keyframes stageBookEntrance {
  0% {
    transform: scale(0.82) translateY(45px) rotateX(10deg) rotateY(-4deg) translateX(0);
    opacity: 0.4;
  }
  30% {
    opacity: 1;
  }
  100% {
    /* Shifts right slightly as the front cover opens toward the left, keeping the entire book spread centered */
    transform: scale(1) translateY(0) rotateX(0deg) rotateY(0deg) translateX(clamp(45px, 14vw, 130px));
    opacity: 1;
  }
}

/* Physical Spine Hinge */
.book-3d-spine {
  position: absolute;
  left: -14px;
  top: 0;
  bottom: 0;
  width: 16px;
  z-index: 35;
  background: linear-gradient(90deg, #181715 0%, #322F2A 45%, #181715 100%);
  border-radius: 4px 0 0 4px;
  box-shadow: -6px 6px 16px rgba(0, 0, 0, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  border-right: 1px solid rgba(255, 255, 255, 0.08);
}

.book-3d-spine-text {
  writing-mode: vertical-rl;
  transform: rotate(180deg);
  font-family: var(--font-sans);
  font-size: 0.55rem;
  font-weight: 700;
  letter-spacing: 0.22em;
  color: #D4AF37;
  opacity: 0.85;
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.8);
}

/* Physical Back Cover (Base) */
.book-3d-back-cover {
  position: absolute;
  inset: -3px -3px -3px -8px;
  z-index: 5;
  background: #141311;
  border-radius: 4px 8px 8px 4px;
  box-shadow: 0 28px 56px rgba(0, 0, 0, 0.65), 0 10px 20px rgba(0, 0, 0, 0.4);
}

/* Static Facing Page Block (Right side of the open spread) */
.book-3d-page-block {
  position: absolute;
  inset: 0;
  z-index: 10;
  background-color: #FAF7F0;
  color: #1A1917;
  border-radius: 2px 7px 7px 2px;
  box-shadow: 14px 20px 40px rgba(0, 0, 0, 0.45);
  overflow: hidden;
  padding: clamp(1.5rem, 4vw, 2.25rem) clamp(1.25rem, 3.5vw, 1.85rem);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.book-3d-page-texture {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image: radial-gradient(rgba(0, 0, 0, 0.03) 1px, transparent 0);
  background-size: 6px 6px;
  opacity: 0.6;
}

.page-gutter-shadow {
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  width: 32px;
  pointer-events: none;
  background: linear-gradient(90deg, rgba(0, 0, 0, 0.32) 0%, rgba(0, 0, 0, 0.12) 40%, transparent 100%);
}

.page-deckle-edge {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  width: 7px;
  pointer-events: none;
  background: repeating-linear-gradient(
    to bottom, 
    #ECE4D4 0px, 
    #ECE4D4 2px, 
    #D6CBBA 3px, 
    #ECE4D4 4px
  );
  box-shadow: inset 1px 0 2px rgba(0, 0, 0, 0.2);
}

.book-3d-page-content {
  position: relative;
  z-index: 2;
  display: flex;
  flex-direction: column;
  height: 100%;
  justify-content: space-between;
  padding-left: 0.85rem;
}

.page-meta-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid rgba(0, 0, 0, 0.08);
  padding-bottom: 0.5rem;
}

.page-archive-tag {
  font-family: var(--font-sans);
  font-size: 0.625rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  color: #787163;
  text-transform: uppercase;
}

.page-vol-tag {
  font-family: var(--font-sans);
  font-size: 0.625rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  color: #928B7D;
}

.page-title-block {
  margin: 0.75rem 0 0.35rem;
}

.page-category-pill {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: 0.625rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: #7C5C1B;
  background: rgba(184, 142, 54, 0.14);
  padding: 0.2rem 0.55rem;
  border-radius: 999px;
  margin-bottom: 0.5rem;
}

.page-book-title {
  font-family: var(--font-serif);
  font-size: clamp(1.35rem, 3.8vw, 1.85rem);
  font-weight: 600;
  line-height: 1.2;
  color: #1A1916;
  margin: 0 0 0.35rem;
}

.page-book-author {
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  color: #645E53;
  margin: 0;
  font-style: italic;
}

.page-divider-flourish {
  text-align: center;
  color: #B5AB9B;
  font-size: 1.15rem;
  line-height: 1;
  margin: 0.4rem 0;
}

.page-thesis-box {
  background: rgba(240, 234, 222, 0.75);
  border-left: 2.5px solid #9C8255;
  padding: 0.75rem 0.85rem;
  border-radius: 0 4px 4px 0;
  margin: 0.35rem 0;
}

.page-thesis-label {
  display: block;
  font-family: var(--font-sans);
  font-size: 0.5625rem;
  font-weight: 700;
  letter-spacing: 0.15em;
  color: #8C7348;
  margin-bottom: 0.3rem;
  text-transform: uppercase;
}

.page-thesis-quote {
  font-family: var(--font-serif);
  font-size: clamp(0.78rem, 2vw, 0.875rem);
  line-height: 1.45;
  color: #2D2A26;
  margin: 0;
  font-style: italic;
  display: -webkit-box;
  -webkit-line-clamp: 4;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.page-entering-hint {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-sans);
  font-size: 0.6875rem;
  font-weight: 600;
  color: #726B5D;
  margin-top: 0.5rem;
  padding-top: 0.5rem;
  border-top: 1px dashed rgba(0, 0, 0, 0.08);
}

.entering-indicator-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: #2E7D32;
  box-shadow: 0 0 6px #2E7D32;
  animation: pulseEntering 1s infinite alternate;
}

@keyframes pulseEntering {
  0% { transform: scale(0.8); opacity: 0.6; }
  100% { transform: scale(1.3); opacity: 1; }
}

/* Middle Parchment Page (Flutters open mid-flight) */
.book-3d-turning-leaf {
  position: absolute;
  inset: 4px 4px 4px 0;
  z-index: 25;
  transform-origin: left center;
  transform-style: preserve-3d;
  pointer-events: none;
  animation: flipParchmentLeaf 860ms cubic-bezier(0.25, 0.9, 0.3, 1) 160ms forwards;
  will-change: transform;
}

@keyframes flipParchmentLeaf {
  0% {
    transform: rotateY(0deg);
    opacity: 1;
  }
  50% {
    transform: rotateY(-82deg) skewY(-2.5deg);
    opacity: 0.95;
  }
  100% {
    transform: rotateY(-148deg) skewY(0deg);
    opacity: 0.85;
  }
}

.turning-leaf-front,
.turning-leaf-back {
  position: absolute;
  inset: 0;
  background-color: #F6F1E6;
  border-radius: 2px 6px 6px 2px;
  box-shadow: 6px 10px 20px rgba(0, 0, 0, 0.15);
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}

.turning-leaf-back {
  transform: rotateY(180deg);
  background-color: #F1ECE0;
}

.leaf-etching {
  position: absolute;
  inset: 2rem;
  border: 1px solid rgba(140, 120, 80, 0.1);
  border-radius: 3px;
}

/* 3D Front Hardcover (Swings open 155 degrees on its spine) */
.book-3d-front-cover {
  position: absolute;
  inset: 0;
  z-index: 30;
  transform-origin: left center;
  transform-style: preserve-3d;
  border-radius: 3px 8px 8px 3px;
  box-shadow: -4px 8px 22px rgba(0, 0, 0, 0.4);
  animation: swingHardcoverOpen 880ms cubic-bezier(0.22, 1, 0.36, 1) 120ms forwards;
  will-change: transform;
}

@keyframes swingHardcoverOpen {
  0% {
    transform: rotateY(0deg);
    box-shadow: -4px 8px 22px rgba(0, 0, 0, 0.4);
  }
  65% {
    transform: rotateY(-162deg);
    box-shadow: 12px 16px 36px rgba(0, 0, 0, 0.5);
  }
  100% {
    transform: rotateY(-155deg);
    box-shadow: 14px 18px 42px rgba(0, 0, 0, 0.55);
  }
}

/* Front Face: Book Cover */
.cover-face-front {
  position: absolute;
  inset: 0;
  border-radius: inherit;
  overflow: hidden;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  background-color: #1E1D1A;
}

.cover-face-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.cover-crease-shadow {
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 24px;
  z-index: 3;
  background: linear-gradient(90deg, rgba(0,0,0,0.5) 0%, rgba(255,255,255,0.18) 22%, rgba(0,0,0,0.2) 40%, transparent 100%);
  pointer-events: none;
}

.cover-sheen-layer {
  position: absolute;
  inset: 0;
  z-index: 4;
  background: linear-gradient(135deg, rgba(255, 255, 255, 0.18) 0%, transparent 50%, rgba(0, 0, 0, 0.35) 100%);
  pointer-events: none;
}

/* Inside Face: Archival Endpaper & Ex Libris Bookplate */
.cover-face-inside {
  position: absolute;
  inset: 0;
  border-radius: 8px 3px 3px 8px;
  overflow: hidden;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  transform: rotateY(180deg);
  background-color: #1C1B18;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
}

.endpaper-pattern {
  position: absolute;
  inset: 0;
  background: 
    radial-gradient(circle at 50% 50%, rgba(255, 240, 210, 0.04) 2px, transparent 2px),
    linear-gradient(45deg, rgba(0, 0, 0, 0.2) 25%, transparent 25%, transparent 75%, rgba(0, 0, 0, 0.2) 75%);
  background-size: 16px 16px;
  opacity: 0.7;
}

.ex-libris-bookplate {
  position: relative;
  z-index: 2;
  background: #FAF6ED;
  color: #1A1916;
  border: 1px solid #C8BD9F;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4), inset 0 0 0 3px #FAF6ED, inset 0 0 0 4px #8C7853;
  padding: 1.25rem 1rem;
  border-radius: 3px;
  text-align: center;
  width: 82%;
  max-width: 200px;
}

.bookplate-border {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.2rem;
}

.bookplate-header {
  font-family: var(--font-sans);
  font-size: 0.5625rem;
  font-weight: 700;
  letter-spacing: 0.24em;
  color: #7A6F5D;
}

.bookplate-brand {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: #1A1916;
  line-height: 1.1;
  margin: 0.15rem 0;
}

.bookplate-sub {
  font-family: var(--font-sans);
  font-size: 0.5rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  color: #8C7853;
  text-transform: uppercase;
}

.bookplate-motto {
  font-family: var(--font-serif);
  font-size: 0.6875rem;
  font-style: italic;
  color: #555047;
  margin-top: 0.35rem;
  line-height: 1.3;
}

.inside-crease-shadow {
  position: absolute;
  right: 0;
  top: 0;
  bottom: 0;
  width: 28px;
  background: linear-gradient(270deg, rgba(0, 0, 0, 0.4) 0%, transparent 100%);
  pointer-events: none;
}

/* Skip Cue */
.book-open-skip-cue {
  position: absolute;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  font-family: var(--font-sans);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  color: rgba(255, 255, 255, 0.45);
  pointer-events: none;
  animation: fadeInSlow 600ms ease 300ms forwards;
  opacity: 0;
}

@keyframes fadeInSlow {
  to { opacity: 1; }
}

/* Reduced motion accessibility */
@media (prefers-reduced-motion: reduce) {
  .book-grid-cover-wrap {
    transition: none !important;
    transform: none !important;
  }
  .book-3d-assembly,
  .book-3d-front-cover,
  .book-3d-turning-leaf {
    animation: none !important;
  }
  .book-open-stage-backdrop {
    display: none !important;
  }
}

/* Mobile Responsiveness for 3D Book Stage Spread */
@media (max-width: 680px) {
  .book-3d-assembly {
    width: 175px;
    height: 260px;
  }

  @keyframes stageBookEntrance {
    0% {
      transform: scale(0.85) translateY(30px) rotateX(8deg) rotateY(-3deg) translateX(0);
      opacity: 0.4;
    }
    30% {
      opacity: 1;
    }
    100% {
      transform: scale(1) translateY(0) rotateX(0deg) rotateY(0deg) translateX(85px);
      opacity: 1;
    }
  }

  .book-3d-page-block {
    padding: 0.85rem 0.65rem;
  }

  .book-3d-page-content {
    padding-left: 0.5rem;
  }

  .page-book-title {
    font-size: 1.05rem;
    margin: 0 0 0.2rem;
  }

  .page-category-pill {
    font-size: 0.52rem;
    padding: 0.15rem 0.4rem;
    margin-bottom: 0.25rem;
  }

  .page-thesis-box {
    padding: 0.4rem 0.55rem;
    margin: 0.2rem 0;
  }

  .page-thesis-quote {
    font-size: 0.68rem;
    -webkit-line-clamp: 3;
    line-height: 1.35;
  }

  .page-entering-hint {
    font-size: 0.58rem;
    margin-top: 0.25rem;
    padding-top: 0.25rem;
  }

  .cover-face-inside {
    padding: 0.75rem;
  }

  .ex-libris-bookplate {
    padding: 0.65rem 0.45rem;
    width: 90%;
  }

  .bookplate-brand {
    font-size: 1.05rem;
  }

  .bookplate-header {
    font-size: 0.5rem;
    letter-spacing: 0.18em;
  }

  .bookplate-sub {
    font-size: 0.45rem;
  }

  .bookplate-motto {
    font-size: 0.55rem;
    margin-top: 0.2rem;
  }
}