/* ═══════════════════════════════════════════════════════════════
   Books Module — z-lib.fm-inspired editorial library layout
   Loaded lazily on first entry to the books page (card 05).
   Preloaded in <head> so the stage transition is FOUC-free.
   ═══════════════════════════════════════════════════════════════ */

#books {
  --bk-bg: #faf8f4;
  --bk-bg-2: #f2efe8;
  --bk-ink: #1a1a1a;
  --bk-ink-2: #444;
  --bk-ink-3: #7a7a7a;
  --bk-ink-4: #aaa;
  --bk-rule: rgba(26, 26, 26, 0.08);
  --bk-rule-strong: rgba(26, 26, 26, 0.16);
  --bk-accent: #2b4a6f;          /* editorial navy — distinct from music red */
  --bk-accent-soft: #5c7a9e;
  --bk-accent-tint: rgba(43, 74, 111, 0.08);
  --bk-ok: #2a7a4e;
  --bk-warn: #a85a1a;
  --bk-card: #ffffff;
  --bk-shadow: 0 2px 12px rgba(26, 26, 26, 0.05), 0 1px 3px rgba(26, 26, 26, 0.04);
  --bk-shadow-strong: 0 8px 28px rgba(26, 26, 26, 0.12), 0 2px 6px rgba(26, 26, 26, 0.06);

  background: var(--bk-bg);
  padding: 0;
  overflow: hidden;
  justify-content: flex-start;
  align-items: stretch;
  font-family: 'Chakra Petch', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  color: var(--bk-ink);
}
#books * { box-sizing: border-box; }

.bk-view { display: none; flex: 1 1 auto; min-height: 0; flex-direction: column; }
.bk-view.bk-active { display: flex; }

/* ─────────────── TOPBAR ─────────────── */

.bk-topbar {
  flex: 0 0 auto;
  height: 64px;
  display: flex;
  align-items: center;
  gap: 20px;
  padding: 0 28px 0 84px;
  border-bottom: 1px solid var(--bk-rule);
  background: rgba(250, 248, 244, 0.96);
  backdrop-filter: blur(8px);
  position: relative;
  z-index: 6;
}
.bk-title-wrap { display: flex; align-items: baseline; gap: 12px; flex-shrink: 0; }
.bk-title {
  font-family: 'Cormorant Garamond', serif;
  font-size: 22px;
  font-weight: 500;
  letter-spacing: 2px;
}
.bk-title-sub {
  font-family: 'Chakra Petch', sans-serif;
  font-size: 9px;
  font-weight: 500;
  letter-spacing: 3px;
  color: var(--bk-ink-4);
  text-transform: uppercase;
}

.bk-search-wrap {
  flex: 1 1 auto;
  max-width: 560px;
  position: relative;
  display: flex;
  align-items: center;
}
.bk-search-icon {
  position: absolute;
  left: 14px;
  font-size: 13px;
  color: var(--bk-ink-3);
  pointer-events: none;
}
.bk-search-input {
  width: 100%;
  height: 40px;
  padding: 0 44px 0 38px;
  background: var(--bk-card);
  border: 1px solid var(--bk-rule-strong);
  border-radius: 22px;
  font: inherit;
  font-size: 14px;
  color: var(--bk-ink);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
.bk-search-input:focus {
  outline: none;
  border-color: var(--bk-accent);
  box-shadow: 0 0 0 3px rgba(43, 74, 111, 0.12);
}
.bk-search-clear {
  position: absolute;
  right: 12px;
  width: 22px;
  height: 22px;
  border: none;
  background: transparent;
  color: var(--bk-ink-3);
  cursor: pointer;
  font-size: 18px;
  line-height: 1;
  display: none;
}
.bk-search-clear.bk-visible { display: block; }
.bk-search-clear:hover { color: var(--bk-accent); }

.bk-agg-label {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 14px;
  background: var(--bk-card);
  border: 1px solid var(--bk-rule-strong);
  border-radius: 20px;
  font-family: 'Chakra Petch', sans-serif;
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 1.5px;
  color: var(--bk-ink-3);
  white-space: nowrap;
}
.bk-agg-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--bk-accent);
  box-shadow: 0 0 0 3px rgba(43, 74, 111, 0.12);
  animation: bkAggPulse 2.4s ease-in-out infinite;
}
@keyframes bkAggPulse {
  0%, 100% { opacity: 0.55; box-shadow: 0 0 0 3px rgba(43, 74, 111, 0.10); }
  50%      { opacity: 1;    box-shadow: 0 0 0 6px rgba(43, 74, 111, 0.04); }
}

/* ─────────────── EMPTY STATE (landing before any query) ─────────────── */

.bk-empty {
  flex: 1 1 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 40px 24px 80px;
  text-align: center;
  color: var(--bk-ink-2);
}
.bk-empty-icon {
  font-size: 60px;
  margin-bottom: 20px;
  color: var(--bk-ink-4);
  font-family: 'Cormorant Garamond', serif;
}
.bk-empty-title {
  font-family: 'Cormorant Garamond', serif;
  font-size: 36px;
  font-weight: 500;
  letter-spacing: 1px;
  color: var(--bk-ink);
  margin-bottom: 8px;
}
.bk-empty-subtitle {
  font-family: 'Chakra Petch', sans-serif;
  font-size: 10px;
  letter-spacing: 4px;
  color: var(--bk-ink-4);
  text-transform: uppercase;
  margin-bottom: 42px;
}
.bk-empty-hint {
  font-size: 13px;
  color: var(--bk-ink-3);
  margin-bottom: 18px;
}
.bk-hot-keywords {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
  max-width: 640px;
}
.bk-hot-kw {
  padding: 8px 18px;
  background: var(--bk-card);
  border: 1px solid var(--bk-rule-strong);
  border-radius: 20px;
  font: inherit;
  font-size: 12px;
  color: var(--bk-ink-2);
  cursor: pointer;
  transition: all 0.18s ease;
}
.bk-hot-kw:hover {
  background: var(--bk-accent);
  border-color: var(--bk-accent);
  color: #fff;
  transform: translateY(-1px);
}

/* ─────────────── RESULTS GRID ─────────────── */

.bk-body {
  flex: 1 1 auto;
  overflow: auto;
  padding: 24px 28px 64px;
}

.bk-status-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 4px 2px 20px;
  font-size: 11px;
  color: var(--bk-ink-3);
  letter-spacing: 0.5px;
}
.bk-status-sources { display: flex; gap: 12px; }
.bk-status-sources span b { color: var(--bk-ink-2); font-weight: 600; }

.bk-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(190px, 1fr));
  gap: 22px;
}

.bk-card {
  display: flex;
  flex-direction: column;
  background: var(--bk-card);
  border: 1px solid var(--bk-rule);
  border-radius: 4px;
  overflow: hidden;
  cursor: pointer;
  transition: transform 0.22s ease, box-shadow 0.22s ease, border-color 0.22s ease;
}
.bk-card:hover {
  transform: translateY(-3px);
  border-color: var(--bk-rule-strong);
  box-shadow: var(--bk-shadow-strong);
}
.bk-card-cover {
  position: relative;
  aspect-ratio: 2 / 3;
  background: linear-gradient(135deg, #e8e4da 0%, #d6d0c2 100%);
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
}
.bk-card-cover img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
.bk-card-cover.bk-no-cover {
  background: linear-gradient(145deg, #eae5d8 0%, #c8bfa8 100%);
}
.bk-card-cover-fallback {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 18px;
  color: rgba(26, 26, 26, 0.45);
  font-family: 'Cormorant Garamond', serif;
  font-size: 15px;
  font-weight: 500;
  line-height: 1.3;
  gap: 8px;
}
.bk-card-cover-fallback::before {
  content: '';
  display: block;
  width: 44px;
  height: 2px;
  background: rgba(26, 26, 26, 0.28);
}

.bk-card-body {
  padding: 12px 14px 14px;
  display: flex;
  flex-direction: column;
  gap: 4px;
  min-height: 88px;
}
.bk-card-title {
  font-family: 'Cormorant Garamond', serif;
  font-size: 15px;
  font-weight: 600;
  line-height: 1.3;
  color: var(--bk-ink);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  text-overflow: ellipsis;
}
.bk-card-author {
  font-size: 11px;
  color: var(--bk-ink-3);
  font-style: italic;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.bk-card-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 8px;
  align-items: center;
  margin-top: 6px;
  font-size: 10px;
  color: var(--bk-ink-3);
  font-family: 'Chakra Petch', sans-serif;
  letter-spacing: 0.3px;
}
.bk-card-badge {
  display: inline-block;
  padding: 2px 6px;
  border-radius: 2px;
  font-size: 9px;
  font-weight: 600;
  letter-spacing: 0.8px;
  text-transform: uppercase;
}
.bk-card-badge.ext-epub { background: rgba(42, 122, 78, 0.12); color: var(--bk-ok); }
.bk-card-badge.ext-pdf  { background: rgba(168, 90, 26, 0.12); color: var(--bk-warn); }
.bk-card-badge.ext-other{ background: rgba(26, 26, 26, 0.06); color: var(--bk-ink-3); }
.bk-card-versions {
  margin-left: auto;
  font-size: 10px;
  color: var(--bk-ink-4);
}

/* ─────────────── LOADING / STATES ─────────────── */

.bk-loading {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 80px 20px;
  gap: 10px;
  color: var(--bk-ink-3);
  font-size: 12px;
  letter-spacing: 1px;
}
.bk-spinner {
  width: 18px;
  height: 18px;
  border: 2px solid var(--bk-rule-strong);
  border-top-color: var(--bk-accent);
  border-radius: 50%;
  animation: bkSpin 0.9s linear infinite;
}
@keyframes bkSpin { to { transform: rotate(360deg); } }

.bk-no-results {
  padding: 70px 20px;
  text-align: center;
  color: var(--bk-ink-3);
  font-size: 13px;
}
.bk-no-results-title {
  font-family: 'Cormorant Garamond', serif;
  font-size: 26px;
  color: var(--bk-ink-2);
  margin-bottom: 6px;
}

/* ─────────────── DETAIL VIEW ─────────────── */

.bk-detail-body {
  flex: 1 1 auto;
  overflow: auto;
  padding: 32px 40px 80px;
}
.bk-detail-back {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: transparent;
  border: none;
  padding: 4px 8px 12px 0;
  color: var(--bk-ink-3);
  font: inherit;
  font-size: 12px;
  cursor: pointer;
  letter-spacing: 0.8px;
  transition: color 0.18s ease;
}
.bk-detail-back:hover { color: var(--bk-accent); }

.bk-detail-wrap {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 44px;
  max-width: 1100px;
  margin: 0 auto;
}
.bk-detail-cover-col { flex-shrink: 0; }
.bk-detail-cover {
  width: 100%;
  aspect-ratio: 2 / 3;
  background: linear-gradient(145deg, #eae5d8 0%, #c8bfa8 100%);
  border-radius: 4px;
  overflow: hidden;
  box-shadow: var(--bk-shadow-strong);
  display: flex;
  align-items: center;
  justify-content: center;
}
.bk-detail-cover img { width: 100%; height: 100%; object-fit: cover; }

.bk-detail-info { min-width: 0; }
.bk-detail-title {
  font-family: 'Cormorant Garamond', serif;
  font-size: 34px;
  font-weight: 600;
  line-height: 1.2;
  margin-bottom: 8px;
  color: var(--bk-ink);
}
.bk-detail-author {
  font-size: 16px;
  color: var(--bk-ink-2);
  font-style: italic;
  margin-bottom: 4px;
}
.bk-detail-sub {
  font-size: 11px;
  color: var(--bk-ink-3);
  font-family: 'Chakra Petch', sans-serif;
  letter-spacing: 1px;
  text-transform: uppercase;
  margin-bottom: 22px;
}
.bk-detail-actions {
  display: flex;
  gap: 12px;
  margin-bottom: 28px;
  flex-wrap: wrap;
}
.bk-btn-primary {
  font: inherit;
  font-size: 13px;
  font-weight: 500;
  letter-spacing: 1px;
  border-radius: 22px;
  border: 1px solid var(--bk-accent);
  padding: 11px 26px;
  cursor: pointer;
  transition: all 0.18s ease;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--bk-accent);
  color: #fff;
}
.bk-btn-primary:hover {
  background: var(--bk-ink);
  border-color: var(--bk-ink);
  transform: translateY(-1px);
}
.bk-btn-primary:disabled {
  background: var(--bk-ink-4);
  border-color: var(--bk-ink-4);
  cursor: not-allowed;
  transform: none;
}

.bk-detail-summary {
  font-size: 14px;
  line-height: 1.72;
  color: var(--bk-ink-2);
  margin-bottom: 28px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--bk-rule);
  text-align: justify;
}
.bk-detail-summary.bk-collapsed {
  display: -webkit-box;
  -webkit-line-clamp: 6;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.bk-summary-toggle {
  background: none;
  border: none;
  color: var(--bk-accent);
  font: inherit;
  font-size: 12px;
  cursor: pointer;
  padding: 4px 0;
  margin-top: -18px;
  margin-bottom: 16px;
}

.bk-detail-facts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 14px 28px;
  margin-bottom: 28px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--bk-rule);
}
.bk-fact-label {
  font-size: 9px;
  color: var(--bk-ink-4);
  font-family: 'Chakra Petch', sans-serif;
  letter-spacing: 2px;
  text-transform: uppercase;
  margin-bottom: 4px;
}
.bk-fact-value {
  font-size: 13px;
  color: var(--bk-ink-2);
}

.bk-versions-title {
  font-family: 'Cormorant Garamond', serif;
  font-size: 20px;
  font-weight: 500;
  color: var(--bk-ink);
  margin-bottom: 4px;
}
.bk-versions-note {
  font-size: 11px;
  color: var(--bk-ink-3);
  margin-bottom: 14px;
}
.bk-versions-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.bk-version-row {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 12px 16px;
  background: var(--bk-card);
  border: 1px solid var(--bk-rule);
  border-radius: 4px;
  transition: border-color 0.18s ease;
}
.bk-version-row:hover { border-color: var(--bk-rule-strong); }
.bk-version-ext {
  font-family: 'Chakra Petch', sans-serif;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 1px;
  text-transform: uppercase;
  padding: 4px 8px;
  border-radius: 2px;
  min-width: 48px;
  text-align: center;
}
.bk-version-ext.ext-epub { background: rgba(42, 122, 78, 0.14); color: var(--bk-ok); }
.bk-version-ext.ext-pdf  { background: rgba(168, 90, 26, 0.14); color: var(--bk-warn); }
.bk-version-ext.ext-other{ background: rgba(26, 26, 26, 0.06); color: var(--bk-ink-3); }
.bk-version-meta {
  flex: 1 1 auto;
  min-width: 0;
  display: flex;
  gap: 14px;
  font-size: 12px;
  color: var(--bk-ink-3);
}
.bk-version-meta b { color: var(--bk-ink-2); font-weight: 500; }
.bk-version-actions { display: flex; gap: 8px; }
.bk-version-btn {
  font: inherit;
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.8px;
  border-radius: 16px;
  padding: 7px 16px;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all 0.18s ease;
}
.bk-version-btn.bk-read {
  background: var(--bk-accent);
  color: #fff;
  border-color: var(--bk-accent);
}
.bk-version-btn.bk-read:hover { background: var(--bk-ink); border-color: var(--bk-ink); }
.bk-version-btn.bk-read:disabled {
  background: var(--bk-ink-4);
  border-color: var(--bk-ink-4);
  cursor: not-allowed;
}

/* ─────────────── READER OVERLAY ─────────────── */

.bk-reader {
  position: absolute;
  inset: 0;
  background: #2a2a2a;
  display: none;
  flex-direction: column;
  z-index: 20;
}
#books .bk-reader.bk-reader-open { display: flex; }

.bk-reader-bar {
  flex: 0 0 auto;
  height: 52px;
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 0 20px;
  background: rgba(26, 26, 26, 0.96);
  color: #e8e4da;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  font-size: 12px;
  backdrop-filter: blur(8px);
}
.bk-reader-close {
  background: transparent;
  border: 1px solid rgba(255, 255, 255, 0.2);
  color: #e8e4da;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  cursor: pointer;
  font-size: 16px;
  line-height: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  transition: all 0.18s ease;
}
.bk-reader-close:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.4);
}
.bk-reader-title-wrap {
  flex: 1 1 auto;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.bk-reader-title {
  font-family: 'Cormorant Garamond', serif;
  font-size: 16px;
  font-weight: 500;
  color: #fff;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.bk-reader-sub {
  font-size: 10px;
  letter-spacing: 1.5px;
  color: rgba(232, 228, 218, 0.6);
  text-transform: uppercase;
}
.bk-reader-controls { display: flex; gap: 8px; }
.bk-reader-btn {
  background: transparent;
  border: 1px solid rgba(255, 255, 255, 0.2);
  color: #e8e4da;
  padding: 6px 14px;
  border-radius: 16px;
  font: inherit;
  font-size: 11px;
  letter-spacing: 0.8px;
  cursor: pointer;
  transition: all 0.18s ease;
}
.bk-reader-btn:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.4);
}
.bk-reader-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.bk-reader-stage {
  flex: 1 1 auto;
  min-height: 0;
  position: relative;
  overflow: hidden;
  display: flex;
  align-items: stretch;
  justify-content: stretch;
  background: #3a3a3a;
}
.bk-reader-pdf, .bk-reader-epub, .bk-reader-text {
  position: absolute;
  inset: 0;
  display: none;
}
.bk-reader-pdf.bk-active,
.bk-reader-epub.bk-active,
.bk-reader-text.bk-active { display: block; }
.bk-pdf-scroll {
  position: absolute;
  inset: 0;
  overflow: auto;
  background: #525659;
  padding: 16px 0 24px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  scroll-behavior: smooth;
}
.bk-pdf-scroll::-webkit-scrollbar { width: 10px; height: 10px; }
.bk-pdf-scroll::-webkit-scrollbar-track { background: rgba(0,0,0,0.2); }
.bk-pdf-scroll::-webkit-scrollbar-thumb { background: rgba(255,255,255,0.25); border-radius: 6px; }
.bk-pdf-scroll::-webkit-scrollbar-thumb:hover { background: rgba(255,255,255,0.4); }

.bk-pdf-page {
  max-width: 94%;
  width: auto;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  background: #fff;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.25);
}
.bk-pdf-page.bk-pdf-pending {
  min-height: 800px;
  width: min(780px, 92%);
  background: #e8e6e0;
  position: relative;
}
.bk-pdf-page.bk-pdf-pending::after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 24px;
  height: 24px;
  margin: -12px 0 0 -12px;
  border: 3px solid rgba(0, 0, 0, 0.15);
  border-top-color: rgba(0, 0, 0, 0.5);
  border-radius: 50%;
  animation: bkSpin 0.9s linear infinite;
}
.bk-pdf-page canvas {
  display: block;
  max-width: 100%;
  height: auto;
}
.bk-reader-epub {
  background: #f5f3ec;
  padding: 20px 0;
  overflow: hidden;
}
.bk-epub-viewer {
  position: absolute;
  inset: 20px 48px;
}

/* Text / HTML reader — shared stage for Gutenberg txt+html books */
.bk-reader-text {
  background: #f5f3ec;
  overflow: auto;
}
.bk-reader-text .bk-txt-body {
  max-width: 760px;
  margin: 28px auto 40px;
  padding: 30px 36px;
  background: #fffdf6;
  border: 1px solid #e7e3d6;
  border-radius: 6px;
  font-family: 'Noto Serif SC', 'Georgia', 'Times New Roman', serif;
  font-size: 15px;
  line-height: 1.75;
  color: #2a2720;
  white-space: pre-wrap;
  word-wrap: break-word;
  box-shadow: 0 1px 8px rgba(0, 0, 0, 0.04);
}
.bk-reader-text .bk-html-frame {
  width: 100%;
  height: 100%;
  border: 0;
  background: #fffdf6;
}
@media (max-width: 720px) {
  .bk-reader-text .bk-txt-body {
    margin: 14px 8px 28px;
    padding: 20px 18px;
    font-size: 14px;
  }
}
.bk-reader-loading {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 14px;
  color: rgba(255, 255, 255, 0.6);
  background: rgba(42, 42, 42, 0.94);
  font-size: 12px;
  letter-spacing: 1.5px;
  text-transform: uppercase;
}
.bk-reader-error {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 14px;
  padding: 20px;
  color: rgba(255, 255, 255, 0.75);
  text-align: center;
}
.bk-reader-error-title {
  font-family: 'Cormorant Garamond', serif;
  font-size: 26px;
  color: #fff;
}
.bk-reader-error-detail {
  font-size: 13px;
  color: rgba(255, 255, 255, 0.55);
  max-width: 480px;
  word-break: break-word;
}
.bk-reader-error-hint {
  font-size: 12px;
  color: rgba(255, 255, 255, 0.4);
  margin-top: 2px;
}

.bk-epub-nav {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 40px;
  height: 56px;
  background: rgba(26, 26, 26, 0.4);
  border: none;
  color: #fff;
  cursor: pointer;
  font-size: 22px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.18s ease;
  z-index: 3;
}
.bk-epub-nav:hover { background: rgba(26, 26, 26, 0.7); }
.bk-epub-nav.bk-prev { left: 0; border-radius: 0 4px 4px 0; }
.bk-epub-nav.bk-next { right: 0; border-radius: 4px 0 0 4px; }

/* ─────────────── TOAST ─────────────── */

.bk-toast {
  position: fixed;
  bottom: 40px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  padding: 12px 24px;
  background: rgba(26, 26, 26, 0.94);
  color: #fff;
  font-size: 12px;
  letter-spacing: 0.8px;
  border-radius: 4px;
  box-shadow: var(--bk-shadow-strong);
  z-index: 100;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.22s ease, transform 0.22s ease;
  max-width: 80vw;
}
.bk-toast.bk-visible {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ─────────────── RESPONSIVE ─────────────── */

@media (max-width: 900px) {
  .bk-topbar { padding: 0 18px 0 72px; gap: 12px; }
  .bk-title-sub, .bk-agg-label { display: none; }
  .bk-body { padding: 20px 18px 60px; }
  .bk-detail-body { padding: 24px 20px 60px; }
  .bk-detail-wrap { grid-template-columns: 1fr; gap: 24px; }
  .bk-detail-cover-col { max-width: 200px; margin: 0 auto; }
  .bk-detail-title { font-size: 26px; }
  .bk-grid { grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); gap: 16px; }
  .bk-card-title { font-size: 13px; }
  .bk-epub-viewer { inset: 20px 52px; }
  .bk-reader-bar { padding: 0 14px; gap: 10px; }
  .bk-reader-sub { display: none; }
}

@media (max-width: 520px) {
  .bk-topbar { height: 56px; padding: 0 12px 0 64px; }
  .bk-search-input { height: 36px; font-size: 13px; }
  .bk-title { font-size: 18px; }
  .bk-grid { grid-template-columns: repeat(auto-fill, minmax(132px, 1fr)); gap: 12px; }
  .bk-empty-title { font-size: 28px; }
  .bk-empty-icon { font-size: 44px; }
  .bk-version-row { flex-wrap: wrap; gap: 10px; }
  .bk-version-meta { order: 2; width: 100%; font-size: 11px; }
  .bk-version-actions { order: 3; width: 100%; justify-content: flex-end; }
  .bk-detail-actions { gap: 8px; }
  .bk-btn-primary { padding: 10px 20px; font-size: 12px; }
  .bk-epub-viewer { inset: 16px 40px; }
}
