/* xuanxin default theme variables */

:root {
  --font-sans: "Inter", "Segoe UI", system-ui, -apple-system, sans-serif;
  --font-mono: "JetBrains Mono", "Fira Code", "Consolas", monospace;
  --font-serif: "Merriweather", "Georgia", "Times New Roman", serif;

  --color-bg: #fafafa;
  --color-surface: #ffffff;
  --color-text: #1a1a2e;
  --color-text-muted: #64748b;
  --color-primary: #4f46e5;
  --color-primary-hover: #4338ca;
  --color-border: #e2e8f0;
  --color-code-bg: #f1f5f9;
  --color-blockquote-bg: #f8fafc;
  --color-shadow: rgba(15, 23, 42, 0.08);
  --color-shadow-hover: rgba(15, 23, 42, 0.14);

  --max-width: 720px;
  --radius: 10px;
  --radius-sm: 6px;
}

*, *::before, *::after { box-sizing: border-box; }

html {
  font-size: 18px;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: calc(var(--max-width) + 80px);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header */
.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(8px);
  background: color-mix(in srgb, var(--color-surface) 92%, transparent);
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-brand {
  display: inline-flex;
  align-items: center;
  gap: 0.65rem;
  min-width: 0;
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-text);
  text-decoration: none;
  letter-spacing: -0.02em;
}

.site-brand:hover { color: var(--color-primary); }

.site-header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.site-logo {
  display: block;
  height: 2.1rem;
  width: auto;
  max-width: min(240px, 52vw);
  flex-shrink: 0;
}

.site-brand-text {
  line-height: 1.2;
  min-width: 0;
}

.lang-switcher {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.35rem 0.75rem;
  font-size: 0.875rem;
}
.lang-switcher-item {
  color: var(--color-text-muted, #666);
  text-decoration: none;
}
.lang-switcher-item:hover {
  color: var(--color-primary, #333);
  text-decoration: underline;
}
.lang-switcher-item.is-current {
  color: var(--color-text, #111);
  font-weight: 600;
}
.lang-switcher-home {
  margin-right: 0.25rem;
  padding-right: 0.75rem;
  border-right: 1px solid var(--color-border, #ddd);
}
.lang-root-list ul {
  list-style: none;
  padding: 0;
  margin: 1.25rem 0 0;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  align-items: stretch;
  width: max-content;
  max-width: 100%;
  min-width: 12.5rem;
}
.lang-root-list .lang-root-link {
  display: flex;
  width: 100%;
  min-width: 12.5rem;
  justify-content: center;
  text-align: center;
  box-sizing: border-box;
}
/* Equal-size language CTAs; color encodes locale. */
.lang-root-link--en {
  --lang-cta: #1d4ed8;
  --lang-cta-hover: #1e40af;
  background: var(--lang-cta);
  box-shadow: 0 4px 14px color-mix(in srgb, var(--lang-cta) 35%, transparent);
}
.lang-root-link--en:hover {
  background: var(--lang-cta-hover);
  box-shadow: 0 6px 18px color-mix(in srgb, var(--lang-cta) 42%, transparent);
}
.lang-root-link--zh,
.lang-root-link--cn {
  --lang-cta: #c2410c;
  --lang-cta-hover: #9a3412;
  background: var(--lang-cta);
  box-shadow: 0 4px 14px color-mix(in srgb, var(--lang-cta) 35%, transparent);
}
.lang-root-link--zh:hover,
.lang-root-link--cn:hover {
  background: var(--lang-cta-hover);
  box-shadow: 0 6px 18px color-mix(in srgb, var(--lang-cta) 42%, transparent);
}
.lang-root-link--tc {
  --lang-cta: #0f766e;
  --lang-cta-hover: #115e59;
  background: var(--lang-cta);
  box-shadow: 0 4px 14px color-mix(in srgb, var(--lang-cta) 35%, transparent);
}
.lang-root-link--tc:hover {
  background: var(--lang-cta-hover);
  box-shadow: 0 6px 18px color-mix(in srgb, var(--lang-cta) 42%, transparent);
}
.lang-root-link--jp {
  --lang-cta: #9f1239;
  --lang-cta-hover: #881337;
  background: var(--lang-cta);
  box-shadow: 0 4px 14px color-mix(in srgb, var(--lang-cta) 35%, transparent);
}
.lang-root-link--jp:hover {
  background: var(--lang-cta-hover);
  box-shadow: 0 6px 18px color-mix(in srgb, var(--lang-cta) 42%, transparent);
}
.lang-root-link--sp {
  --lang-cta: #a16207;
  --lang-cta-hover: #854d0e;
  background: var(--lang-cta);
  box-shadow: 0 4px 14px color-mix(in srgb, var(--lang-cta) 35%, transparent);
}
.lang-root-link--sp:hover {
  background: var(--lang-cta-hover);
  box-shadow: 0 6px 18px color-mix(in srgb, var(--lang-cta) 42%, transparent);
}
.lang-root-link--compare {
  --lang-cta: #4c1d95;
  --lang-cta-hover: #5b21b6;
  background: var(--lang-cta);
  box-shadow: 0 4px 14px color-mix(in srgb, var(--lang-cta) 35%, transparent);
}
.lang-root-link--compare:hover {
  background: var(--lang-cta-hover);
  box-shadow: 0 6px 18px color-mix(in srgb, var(--lang-cta) 42%, transparent);
}
.site-header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-shrink: 0;
}

.site-purchase-link {
  display: inline-flex;
  align-items: center;
  padding: 0.5rem 1rem;
  border: none;
  border-radius: var(--radius-sm);
  background: var(--color-primary);
  color: #fff;
  font-size: 0.88rem;
  font-weight: 600;
  text-decoration: none;
  white-space: nowrap;
  box-shadow: 0 4px 14px color-mix(in srgb, var(--color-primary) 35%, transparent);
  transition: background 0.15s, transform 0.15s, box-shadow 0.15s;
}

.site-purchase-link:hover {
  background: var(--color-primary-hover);
  color: #fff;
  transform: translateY(-1px);
  box-shadow: 0 6px 18px color-mix(in srgb, var(--color-primary) 42%, transparent);
}

.site-nav a {
  color: var(--color-text-muted);
  text-decoration: none;
  font-size: 0.9rem;
}

.site-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex: 1;
  flex-wrap: nowrap;
  gap: 1rem;
  width: 100%;
}

.site-nav-start {
  display: flex;
  align-items: center;
  flex-wrap: nowrap;
  gap: 0.75rem;
}

.site-nav a:hover { color: var(--color-primary); }

.site-nav .lang-toggle {
  display: inline-flex;
  align-items: center;
  flex-shrink: 0;
  margin: 0;
  white-space: nowrap;
  padding: 0.4rem 0.8rem;
  border: 1px solid #cbd5e1;
  border-radius: 6px;
  background: #fff;
  box-shadow: 0 1px 3px rgba(15, 23, 42, 0.1);
  font: inherit;
  font-size: 0.85rem;
  line-height: 1.4;
  color: #64748b;
  cursor: pointer;
  text-decoration: none;
  transition: color 0.15s, border-color 0.15s, box-shadow 0.15s;
}

.site-nav .lang-toggle:hover {
  color: #1e3a8a;
  border-color: #94a3b8;
  box-shadow: 0 2px 8px rgba(15, 23, 42, 0.12);
  text-decoration: none;
}

/* Index / book home */
.index-hero {
  padding: 3rem 0 2rem;
  text-align: center;
}

.index-hero h1 {
  font-size: 2.4rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin: 0 0 0.5rem;
}

.index-desc,
.book-home-desc {
  color: var(--color-text-muted);
  font-size: 1.05rem;
  max-width: 540px;
  margin: 0;
  line-height: 1.6;
}

.index-count {
  color: var(--color-text-muted);
  font-size: 0.85rem;
}

/* Book home page */
.bubble-book-index .site-header-minimal .site-brand {
  font-size: 0.95rem;
  max-width: min(100%, 28rem);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.book-home-hero {
  padding: 2.5rem 0 3rem;
  background: linear-gradient(
    180deg,
    color-mix(in srgb, var(--color-primary) 7%, var(--color-bg)) 0%,
    var(--color-bg) 72%
  );
  border-bottom: 1px solid var(--color-border);
}

.book-home-hero-inner {
  display: grid;
  gap: 2rem 2.5rem;
  align-items: center;
  max-width: calc(var(--max-width) + 280px);
}

.book-home-intro {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.75rem;
  min-width: 0;
}

.book-home-eyebrow {
  margin: 0;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-primary);
}

.book-home-title {
  margin: 0;
  font-size: clamp(1.85rem, 4vw, 2.65rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.15;
}

.book-home-meta {
  margin: 0;
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

.book-home-actions {
  margin-top: 0.35rem;
}

.book-home-cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.72rem 1.35rem;
  border-radius: var(--radius-sm);
  background: var(--color-primary);
  color: #fff;
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  box-shadow: 0 4px 14px color-mix(in srgb, var(--color-primary) 35%, transparent);
  transition: background 0.15s, transform 0.15s, box-shadow 0.15s;
}

.book-home-cta:hover {
  background: var(--color-primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 6px 18px color-mix(in srgb, var(--color-primary) 42%, transparent);
}

.book-cover {
  margin: 0;
  max-width: min(320px, 78vw);
  justify-self: center;
}

.book-cover img {
  display: block;
  width: 100%;
  height: auto;
  border: none;
  border-radius: 0;
  box-shadow: none;
}

.book-home-toc {
  padding: 2.5rem 0 3.5rem;
}

.book-home-toc-header {
  margin-bottom: 1.25rem;
}

.book-home-toc-heading {
  margin: 0;
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--color-text);
}

@media (min-width: 768px) {
  .book-home-hero-inner {
    grid-template-columns: minmax(220px, 320px) minmax(0, 1fr);
  }

  .book-cover {
    justify-self: end;
    max-width: 320px;
  }

  .book-toc-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.55rem 1rem;
  }
}

@media (min-width: 1024px) {
  .book-home-hero-inner {
    max-width: 980px;
    gap: 2.5rem 3.5rem;
  }

  .book-home-toc .container {
    max-width: 980px;
  }
}

.post-list {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  padding-bottom: 3rem;
}

.post-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.5rem 1.75rem;
  box-shadow: 0 1px 3px var(--color-shadow);
  transition: box-shadow 0.2s, transform 0.2s;
}

.post-card:hover {
  box-shadow: 0 8px 24px var(--color-shadow-hover);
  transform: translateY(-2px);
}

.post-card h2 {
  margin: 0 0 0.5rem;
  font-size: 1.35rem;
  letter-spacing: -0.02em;
}

.post-card h2 a {
  color: var(--color-text);
  text-decoration: none;
}

.post-card h2 a:hover { color: var(--color-primary); }

.post-excerpt {
  color: var(--color-text-muted);
  margin: 0.5rem 0;
  font-size: 0.95rem;
}

.read-more {
  display: inline-block;
  margin-top: 0.75rem;
  color: var(--color-primary);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.9rem;
}

.read-more:hover { color: var(--color-primary-hover); }

.empty {
  text-align: center;
  color: var(--color-text-muted);
  padding: 3rem;
}

.empty code {
  background: var(--color-code-bg);
  padding: 0.15rem 0.4rem;
  border-radius: var(--radius-sm);
  font-size: 0.85em;
}

/* Post page */
.post {
  background: var(--color-surface);
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  box-shadow: 0 2px 12px var(--color-shadow);
  padding: 2.5rem 2rem;
  margin: 2rem auto 3rem;
  max-width: var(--max-width);
}

.post-header { margin-bottom: 2rem; }

.post-title {
  font-size: 2.2rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin: 0 0 1rem;
}

.post-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  color: var(--color-text-muted);
  font-size: 0.85rem;
}

.post-meta time::before { content: "📅 "; }

.post-author::before { content: "✍️ "; }

.post-lead {
  font-size: 1.1rem;
  color: var(--color-text-muted);
  border-left: 4px solid var(--color-primary);
  padding: 0.75rem 1rem;
  margin: 1.25rem 0 0;
  background: var(--color-blockquote-bg);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.post-featured {
  margin: 1.5rem 0 0;
}

.post-featured img {
  width: 100%;
  border-radius: var(--radius);
  box-shadow: 0 4px 16px var(--color-shadow);
}

.post-tags, .post-card .post-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 0.75rem;
}

.tag {
  display: inline-block;
  padding: 0.2rem 0.6rem;
  font-size: 0.75rem;
  font-weight: 500;
  background: var(--color-code-bg);
  color: var(--color-text-muted);
  border-radius: 999px;
  border: 1px solid var(--color-border);
}

/* Prose — markdown body (memoir: one markdown line → one <p>, keep gaps tight) */
.prose {
  font-family: var(--font-serif);
  font-size: 1rem;
  line-height: 1.55;
  color: var(--color-text);
  --prose-line-gap: 0.15rem;
}

.prose > :first-child { margin-top: 0; }

.prose h1, .prose h2, .prose h3, .prose h4, .prose h5, .prose h6 {
  font-family: var(--font-sans);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.3;
  margin-top: 2rem;
  margin-bottom: 0.75rem;
}

.prose h1 { font-size: 1.8rem; }
.prose h2 { font-size: 1.5rem; border-bottom: 1px solid var(--color-border); padding-bottom: 0.3rem; scroll-margin-top: 4rem; scroll-margin-bottom: 1rem; }
.prose h3 { font-size: 1.25rem; }

/* Book chapter pages — smaller reading size, wider column */
html:has(body.bubble-book-page) {
  font-size: 15px;
  --max-width: 960px;
}

body.bubble-book-page .container {
  max-width: calc(var(--max-width) + 100px);
}

body.bubble-book-page .post {
  max-width: var(--max-width);
}

body.bubble-book-page .post-title {
  font-size: 1.55rem;
}

body.bubble-book-page .prose {
  font-size: 0.94rem;
  line-height: 1.58;
}

body.bubble-book-page .prose h1 { font-size: 1.45rem; }
body.bubble-book-page .prose h2 { font-size: 1.2rem; scroll-margin-top: 3.5rem; }
body.bubble-book-page .prose h3 { font-size: 1.05rem; }
body.bubble-book-page .prose pre { font-size: 0.8rem; }
body.bubble-book-page .prose table { font-size: 0.85rem; }

.prose p { margin: 0 0 var(--prose-line-gap); }

.prose .math-display {
  margin: 0.85rem 0 1rem;
  overflow-x: auto;
  text-align: center;
}

.prose .math-display mjx-container[display="true"] {
  margin: 0 auto !important;
}

/* Lone ``\\`` in source → bubble ``\\hfill\\break`` in PDF (one extra line, not a full paragraph) */
.prose p:has(+ .xuanxin-blank) {
  margin-bottom: 0;
}

.prose .xuanxin-blank {
  display: block;
  height: 1lh;
  margin: 0;
  padding: 0;
}

/* LaTeX ``\\newpage`` / ``\\clearpage`` → CSS page break (bubble EPUB hook) */
.prose .xuanxin-pagebreak {
  display: none;
}

/* Paginated reader (one screen per \\newpage) */
body.xuanxin-paginated .post-paginated {
  display: flex;
  flex-direction: column;
  min-height: calc(100vh - 10rem);
}

body.xuanxin-paginated .post-paginated:has(.fullpage-image) {
  min-height: 0;
}

.prose.prose-paginated {
  flex: 1;
  display: flex;
  flex-direction: column;
}

body.xuanxin-paginated .prose-paginated:has(.fullpage-image) {
  flex: 0 1 auto;
}

.xuanxin-paginated-reader {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;
}

body.xuanxin-paginated .xuanxin-paginated-reader:has(.fullpage-image) {
  flex: 0 1 auto;
}

.xuanxin-page {
  flex: 1;
  overflow-y: auto;
  padding: 0.5rem 0 1.5rem;
}

body.xuanxin-paginated .xuanxin-page:has(> .fullpage-image) {
  flex: 0 0 auto;
  overflow: visible;
  padding-top: 0;
  padding-bottom: 0.75rem;
}

body.xuanxin-paginated .xuanxin-page.bubble-dedication-page {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  min-height: min(72vh, 42rem);
  padding: 3rem 1.5rem;
  text-align: center;
}

body.xuanxin-paginated .xuanxin-page.bubble-dedication-page h1 {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

body.xuanxin-paginated .xuanxin-page.bubble-dedication-page .bubble-centersection {
  margin: 0 auto;
  min-height: 0;
  max-width: 28rem;
  font-size: 1.08rem;
  line-height: 1.75;
}

body.xuanxin-paginated .xuanxin-page.bubble-dedication-page .bubble-centersection p {
  margin: 0 0 1rem;
}

body.xuanxin-paginated .xuanxin-page.bubble-dedication-page .bubble-centersection p:last-child {
  margin-bottom: 0;
  font-style: normal;
  color: var(--color-text-muted);
}

.bubble-section-sidebar.is-hidden-on-page {
  visibility: hidden;
  pointer-events: none;
}

.xuanxin-page[hidden] {
  display: none !important;
}

.page-nav {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 0.75rem;
  margin: 1rem 0;
  padding: 0.75rem 0;
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
}

.page-nav-bottom {
  margin-top: auto;
}

.page-nav-btn {
  font: inherit;
  font-size: 0.92rem;
  color: var(--color-primary);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 0.5rem 0.85rem;
  cursor: pointer;
  transition: border-color 0.15s, box-shadow 0.15s;
}

.page-nav-btn:hover:not(:disabled) {
  border-color: var(--color-primary);
  box-shadow: 0 2px 8px var(--color-shadow);
}

.page-nav-btn:disabled {
  opacity: 0.35;
  cursor: default;
}

.page-nav-prev { justify-self: start; }
.page-nav-next { justify-self: end; }

.page-nav-indicator {
  justify-self: center;
  color: var(--color-text-muted);
  font-size: 0.9rem;
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

body.xuanxin-paginated .prose .fullpage-image {
  width: 100%;
  height: auto;
  min-height: 0;
  margin: 0;
  page-break-before: auto;
  break-before: auto;
}

body.xuanxin-paginated .prose .fullpage-image.is-rotated-side img {
  max-width: 100% !important;
  max-height: none !important;
  width: auto !important;
  height: auto !important;
}

@media print {
  .prose .xuanxin-pagebreak {
    display: block;
    page-break-before: always;
    break-before: page;
    margin: 0;
    padding: 0;
    height: 0;
    border: 0;
    overflow: hidden;
  }

  .xuanxin-page[hidden] {
    display: block !important;
  }

  .page-nav,
  .chapter-nav,
  .xuanxin-section-nav,
  .xuanxin-fullpage-controls,
  .xuanxin-fullpage-lightbox {
    display: none !important;
  }
}

/* Extra breathing room before/after section headings */
.prose h2 + p,
.prose h3 + p {
  margin-top: 0.5rem;
}

.prose a {
  color: var(--color-primary);
  text-decoration: underline;
  text-underline-offset: 2px;
}

.prose a:hover { color: var(--color-primary-hover); }

.prose ul, .prose ol {
  margin: 0 0 1.2rem;
  padding-left: 1.5rem;
}

.prose li { margin-bottom: 0.4rem; }

.prose blockquote {
  border-left: 4px solid var(--color-primary);
  background: var(--color-blockquote-bg);
  margin: 1.5rem 0;
  padding: 0.75rem 1.25rem;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--color-text-muted);
  font-style: italic;
}

/* Bubble-style NOTES/IMPORS/WARNS/AIMLS sections */
.prose aside.xuanxin-notesection,
.prose aside.xuanxin-importantsection,
.prose aside.xuanxin-warnsection,
.prose aside.xuanxin-aimlsection {
  display: block;
  margin: 1rem 0;
  padding: 0.65rem 0.85rem 0.65rem 2.1rem;
  border-radius: var(--radius-sm);
  border: 0.8px solid;
  font-size: 0.92rem;
  line-height: 1.55;
  position: relative;
}

.prose aside.xuanxin-notesection::before,
.prose aside.xuanxin-importantsection::before,
.prose aside.xuanxin-warnsection::before,
.prose aside.xuanxin-aimlsection::before {
  position: absolute;
  left: 0.55rem;
  top: 0.65rem;
  font-size: 1rem;
  line-height: 1;
}

.prose aside.xuanxin-notesection {
  background: color-mix(in srgb, #facc15 12%, var(--color-surface));
  border-color: color-mix(in srgb, var(--color-primary) 55%, #94a3b8);
  color: var(--color-text);
  font-style: normal;
}

.prose aside.xuanxin-notesection::before { content: "📝"; }

.prose aside.xuanxin-importantsection {
  background: color-mix(in srgb, var(--color-primary) 10%, var(--color-surface));
  border-color: color-mix(in srgb, var(--color-primary) 70%, #64748b);
  color: var(--color-text);
  font-style: normal;
}

.prose aside.xuanxin-importantsection::before { content: "ℹ️"; }

.prose aside.xuanxin-warnsection {
  background: color-mix(in srgb, #f97316 12%, var(--color-surface));
  border-color: color-mix(in srgb, #f97316 55%, #94a3b8);
  color: var(--color-text);
  font-style: normal;
}

.prose aside.xuanxin-warnsection::before { content: "⚠️"; }

.prose aside.xuanxin-aimlsection {
  background: color-mix(in srgb, #22d3ee 12%, var(--color-surface));
  border-color: color-mix(in srgb, var(--color-primary) 60%, #22d3ee);
  color: var(--color-text);
  font-style: normal;
}

.prose aside.xuanxin-aimlsection::before { content: "🤖"; }

.prose aside.xuanxin-notesection > :first-child,
.prose aside.xuanxin-importantsection > :first-child,
.prose aside.xuanxin-warnsection > :first-child,
.prose aside.xuanxin-aimlsection > :first-child {
  margin-top: 0;
}

.prose aside.xuanxin-notesection > :last-child,
.prose aside.xuanxin-importantsection > :last-child,
.prose aside.xuanxin-warnsection > :last-child,
.prose aside.xuanxin-aimlsection > :last-child {
  margin-bottom: 0;
}

.prose aside.xuanxin-notesection p,
.prose aside.xuanxin-importantsection p,
.prose aside.xuanxin-warnsection p,
.prose aside.xuanxin-aimlsection p {
  margin: 0 0 var(--prose-line-gap);
}

/* Peanutbook CENTERS-CENTERE (dedication / epigraph) */
.prose aside.bubble-centersection {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  margin: 2.5rem auto;
  padding: 1.5rem 1rem;
  min-height: 10rem;
  font-style: italic;
}

.prose aside.bubble-centersection > :first-child {
  margin-top: 0;
}

.prose aside.bubble-centersection > :last-child {
  margin-bottom: 0;
}

/* GALLERYS/GALLERYE image carousel */
.prose .xuanxin-gallery {
  margin: 0.75rem 0;
  border: 1px solid color-mix(in srgb, var(--color-border, #cbd5e1) 80%, transparent);
  border-radius: var(--radius-sm);
  overflow: hidden;
  background: var(--color-surface);
}

.prose .xuanxin-gallery-viewport {
  height: 168px;
  overflow: hidden;
  background: color-mix(in srgb, var(--color-bg) 92%, #000 8%);
}

.prose .xuanxin-gallery:not(.xuanxin-gallery-has-captions) .xuanxin-gallery-viewport {
  height: 188px;
}

.prose .xuanxin-gallery-single .xuanxin-gallery-viewport {
  height: 188px;
}

.prose .xuanxin-gallery-single:not(.xuanxin-gallery-has-captions) .xuanxin-gallery-viewport {
  height: 200px;
}

.prose .xuanxin-gallery-track {
  display: flex;
  height: 100%;
  transition: transform 0.25s ease;
}

.prose .xuanxin-gallery-slide {
  flex: 0 0 100%;
  width: 100%;
  height: 100%;
  margin: 0;
  padding: 0.15rem;
  box-sizing: border-box;
  display: flex;
  align-items: center;
  justify-content: center;
}

.prose .xuanxin-gallery-slide img {
  max-height: 100%;
  max-width: 100%;
  width: auto;
  height: auto;
  object-fit: contain;
  display: block;
  margin: 0;
}

.prose .xuanxin-gallery-slide video,
.prose .xuanxin-gallery-video {
  max-height: 100%;
  max-width: 100%;
  width: auto;
  height: auto;
  object-fit: contain;
  display: block;
  margin: 0;
  background: #000;
}

.prose .xuanxin-encrypted-media[hidden] {
  display: none;
}

.prose .xuanxin-gallery-caption {
  display: block;
  width: 100%;
  box-sizing: border-box;
  margin: 0;
  padding: 0.3rem 0.55rem;
  font: inherit;
  font-size: 0.8rem;
  line-height: 1.3;
  text-align: left;
  color: var(--color-text-muted);
  background: color-mix(in srgb, var(--color-bg) 96%, transparent);
  border: 0;
  border-top: 1px solid color-mix(in srgb, var(--color-border, #cbd5e1) 80%, transparent);
  cursor: pointer;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.prose .xuanxin-gallery-caption[hidden] {
  display: none;
}

.prose .xuanxin-gallery-caption:hover {
  color: var(--color-text);
}

.prose .xuanxin-gallery-caption[aria-expanded="true"] {
  white-space: normal;
  color: var(--color-text);
  max-height: 4.5rem;
  overflow-y: auto;
}

.prose .xuanxin-gallery-controls {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 0.5rem;
  padding: 0.3rem 0.45rem;
  border-top: 1px solid color-mix(in srgb, var(--color-border, #cbd5e1) 80%, transparent);
}

.prose .xuanxin-gallery-btn {
  appearance: none;
  border: 1px solid color-mix(in srgb, var(--color-border, #cbd5e1) 80%, transparent);
  background: var(--color-surface);
  color: var(--color-text);
  border-radius: var(--radius-sm);
  padding: 0.2rem 0.55rem;
  font: inherit;
  font-size: 0.9rem;
  line-height: 1.2;
  cursor: pointer;
}

.prose .xuanxin-gallery-btn:hover:not(:disabled) {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.prose .xuanxin-gallery-btn:disabled {
  opacity: 0.35;
  cursor: default;
}

.prose .xuanxin-gallery-indicator {
  text-align: center;
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

.prose .xuanxin-gallery-lock {
  margin: 0.75rem 0;
  border: 1px solid color-mix(in srgb, var(--color-border, #cbd5e1) 80%, transparent);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  overflow: hidden;
}

.xuanxin-entry-lock {
  margin: 1rem 0 0;
  border: 1px solid color-mix(in srgb, var(--color-border, #cbd5e1) 80%, transparent);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
}

.xuanxin-entry-lock.is-unlocked {
  margin: 0;
  border: 0;
  background: transparent;
}

.prose .xuanxin-gallery-lock.is-unlocked .xuanxin-gallery-unlock,
.xuanxin-entry-lock.is-unlocked .xuanxin-gallery-unlock {
  display: none;
}

.prose .xuanxin-gallery-unlock,
.xuanxin-entry-lock .xuanxin-gallery-unlock {
  margin: 0;
  padding: 0.85rem 0.75rem;
  display: grid;
  gap: 0.45rem;
}

.prose .xuanxin-gallery-unlock-label,
.xuanxin-entry-lock .xuanxin-gallery-unlock-label {
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.prose .xuanxin-gallery-unlock-row,
.xuanxin-entry-lock .xuanxin-gallery-unlock-row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 0.45rem;
}

.prose .xuanxin-gallery-unlock-input,
.xuanxin-entry-lock .xuanxin-gallery-unlock-input {
  font: inherit;
  font-size: 0.9rem;
  padding: 0.35rem 0.55rem;
  border: 1px solid color-mix(in srgb, var(--color-border, #cbd5e1) 80%, transparent);
  border-radius: var(--radius-sm);
  background: var(--color-bg);
  color: var(--color-text);
}

.prose .xuanxin-gallery-unlock-btn,
.xuanxin-entry-lock .xuanxin-gallery-unlock-btn {
  appearance: none;
  border: 1px solid color-mix(in srgb, var(--color-border, #cbd5e1) 80%, transparent);
  background: var(--color-surface);
  color: var(--color-text);
  border-radius: var(--radius-sm);
  padding: 0.35rem 0.75rem;
  font: inherit;
  cursor: pointer;
}

.prose .xuanxin-gallery-unlock-btn:hover,
.xuanxin-entry-lock .xuanxin-gallery-unlock-btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.prose .xuanxin-gallery-unlock-error,
.xuanxin-entry-lock .xuanxin-gallery-unlock-error {
  margin: 0;
  font-size: 0.82rem;
  color: #dc2626;
}

.prose .xuanxin-gallery-lock .xuanxin-gallery {
  margin: 0;
  border: 0;
  border-radius: 0;
}

.prose .xuanxin-gallery-lock .xuanxin-gallery[hidden] {
  display: none;
}

.prose code {
  font-family: var(--font-mono);
  font-size: 0.88em;
  background: var(--color-code-bg);
  padding: 0.15rem 0.4rem;
  border-radius: var(--radius-sm);
}

.prose pre.codeblock {
  background: #1e293b;
  color: #e2e8f0;
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-size: 0.85rem;
  line-height: 1.6;
}

.prose pre.bash-codeblock {
  background: #f3faf3;
  color: #1e293b;
  border: 1px solid #d8ead8;
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-size: 0.85rem;
  line-height: 1.6;
}

.prose pre.cpp-codeblock {
  background: #fdf2f8;
  color: #1e293b;
  border: 1px solid #f5d0e6;
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-size: 0.85rem;
  line-height: 1.6;
}

.prose pre.java-codeblock {
  background: #f5f3ff;
  color: #1e293b;
  border: 1px solid #ddd6fe;
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-size: 0.85rem;
  line-height: 1.6;
}

.prose pre.js-codeblock {
  background: #fff7ed;
  color: #1e293b;
  border: 1px solid #fed7aa;
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-size: 0.85rem;
  line-height: 1.6;
}

.prose pre.go-codeblock {
  background: #ecfeff;
  color: #1e293b;
  border: 1px solid #a5f3fc;
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-size: 0.85rem;
  line-height: 1.6;
}

.prose pre.rust-codeblock {
  background: #faf5f0;
  color: #1e293b;
  border: 1px solid #e7d5c4;
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-size: 0.85rem;
  line-height: 1.6;
}

.prose pre.cs-codeblock {
  background: #eff6ff;
  color: #1e293b;
  border: 1px solid #bfdbfe;
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-size: 0.85rem;
  line-height: 1.6;
}

.prose pre.sql-codeblock {
  background: #f0fdfa;
  color: #1e293b;
  border: 1px solid #99f6e4;
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-size: 0.85rem;
  line-height: 1.6;
}

.prose pre.terminal-codeblock {
  background: #f5f5f5;
  color: #000000;
  border: 1px solid #000000;
  border-left: 4px solid #000000;
  border-radius: 4px;
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-size: 0.85rem;
  line-height: 1.6;
}

.prose pre.no-border-radius-codeblock {
  border-radius: 0;
}

.prose pre.no-border-line-codeblock {
  border: none;
}

.prose pre {
  background: #1e293b;
  color: #e2e8f0;
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-size: 0.85rem;
  line-height: 1.6;
}

.prose pre code {
  background: transparent;
  padding: 0;
  color: inherit;
  font-size: inherit;
}

.prose pre.codeblock code,
.prose pre.bash-codeblock code,
.prose pre.cpp-codeblock code,
.prose pre.java-codeblock code,
.prose pre.js-codeblock code,
.prose pre.go-codeblock code,
.prose pre.rust-codeblock code,
.prose pre.cs-codeblock code,
.prose pre.sql-codeblock code,
.prose pre.no-border-radius-codeblock code,
.prose pre.no-border-line-codeblock code,
.prose pre.terminal-codeblock code {
  background: transparent;
  padding: 0;
  color: inherit;
  font-size: inherit;
}

.prose .highlight { border-radius: var(--radius); overflow: hidden; }

.prose table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  font-size: 0.9rem;
  font-family: var(--font-sans);
}

.prose th, .prose td {
  border: 1px solid var(--color-border);
  padding: 0.6rem 0.9rem;
  text-align: left;
}

.prose th {
  background: var(--color-code-bg);
  font-weight: 600;
}

.prose tr:nth-child(even) { background: var(--color-blockquote-bg); }

.prose img {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius);
  margin: 1.25rem 0;
  -webkit-user-drag: none;
  user-select: none;
  -webkit-touch-callout: none;
}

.prose .tp-image-section img,
.prose .fullpage-image img,
.post-featured img {
  -webkit-user-drag: none;
  user-select: none;
  -webkit-touch-callout: none;
}

/* Chapter opening artwork from **tp_image** — flat, bottom-right in opening block */
.prose .tp-image-section {
  margin: 1.1em 0;
}

/* Quote above, image below (no overlap — quote bg would hide the art) */
.prose .tp-image-section:has(blockquote) {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
}

.prose .tp-image-section:has(blockquote) blockquote {
  align-self: stretch;
  margin-bottom: 0;
}

.prose .tp-image-section img.tp-image {
  margin: 0;
  border: none;
  border-radius: 0;
  box-shadow: none;
}

.prose .tp-image-section img.tp-image:hover {
  box-shadow: none;
}

/* Opening block is only the image (no blockquote above) */
.prose .tp-image-section:has(> img.tp-image:only-child) {
  display: flex;
  justify-content: flex-end;
}

/* Bubble-style placement modes (see docs/markdown_syntax_extensions.md) */
.prose img.background {
  margin: 0;
  padding: 0;
  border-radius: 0;
  box-shadow: none;
}

.prose img.background:hover {
  box-shadow: none;
}

.prose .image-background-section {
  position: relative;
  isolation: isolate;
  margin: 1.5rem 0;
}

.prose .image-background-section.image-background-bottom-right,
.prose .image-background-section.image-background-top-right {
  margin: 0;
}

.prose .image-background-section > img.background {
  position: absolute;
  z-index: 0;
  pointer-events: none;
  margin: 0;
  border-radius: 0;
  box-shadow: none;
}

.prose .image-background-section > img.background.bottom-right {
  left: auto;
  top: auto;
  width: auto;
  height: auto;
  max-width: 100%;
}

.prose .image-background-section > img.background.top-right {
  left: auto;
  bottom: auto;
  width: auto;
  height: auto;
  max-width: 100%;
}

.prose .image-background-section > :not(img.background) {
  position: relative;
  z-index: 1;
}

/* Stacked full-bleed backgrounds: N images, one band per paired text.
   Each band's own height comes from its own text (no fixed/viewport-
   relative height, no internal scrollbar) -- a fixed height here used to
   mean a short browser window shrank the band below what its text
   needed, forcing it to scroll internally even though the same text
   fit fine in a tall window. The tradeoff: two bands paired with very
   different text lengths can now end up visibly different heights,
   instead of always matching. */
.prose .image-background-stack {
  display: flex;
  flex-direction: column;
  margin: 1.5rem 0;
}

.prose .image-background-stack > .image-background-section.image-background-stack-item {
  margin: 0;
  position: relative;
  isolation: isolate;
}

.prose .image-background-stack > .image-background-section.image-background-stack-item > img.background {
  position: absolute;
  inset: 0;
  width: 100% !important;
  height: 100% !important;
  max-width: none !important;
  object-fit: cover;
  margin: 0;
}

.prose figure.image-block {
  margin: 1.5rem 0;
  text-align: center;
}

.prose figure.image-block img {
  margin: 0 auto 0.5rem;
}

.prose figure.image-block figcaption {
  font-family: var(--font-sans);
  font-size: 0.9rem;
  color: var(--color-text-muted);
  font-style: italic;
}

.prose .fullpage-image {
  page-break-before: always;
  break-before: page;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 2rem 0;
  overflow: visible;
  position: relative;
}

@media print {
  .prose .fullpage-image {
    min-height: 100vh;
  }
}

.prose .fullpage-image img {
  margin: 0;
  transition: transform 0.35s ease;
  transform-origin: center center;
}

.prose .fullpage-image.is-rotated-side img {
  max-width: min(75vh, 100%) !important;
  max-height: 100vw !important;
  width: auto !important;
  height: auto !important;
}

.xuanxin-fullpage-controls[hidden] {
  display: none !important;
}

.prose .fullpage-image .xuanxin-fullpage-controls {
  position: absolute;
  right: 1rem;
  bottom: 1rem;
  left: auto;
  z-index: 5;
  display: flex;
  gap: 0.4rem;
}

.xuanxin-fullpage-controls {
  display: flex;
  gap: 0.4rem;
}

.xuanxin-fullpage-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.4rem;
  height: 2.4rem;
  padding: 0;
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 600;
  line-height: 1;
  color: var(--color-primary);
  background: color-mix(in srgb, var(--color-surface) 96%, transparent);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--color-border);
  border-radius: 999px;
  box-shadow: 0 4px 16px var(--color-shadow);
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}

.xuanxin-fullpage-icon {
  display: block;
}

.xuanxin-fullpage-btn:hover,
.xuanxin-fullpage-btn:focus-visible {
  color: #fff;
  background: var(--color-primary);
  border-color: var(--color-primary);
  outline: none;
}

.xuanxin-fullpage-lightbox {
  position: fixed;
  inset: 0;
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
}

.xuanxin-fullpage-lightbox[hidden] {
  display: none !important;
}

.xuanxin-fullpage-lightbox-backdrop {
  position: absolute;
  inset: 0;
  padding: 0;
  border: 0;
  background: color-mix(in srgb, #0f172a 88%, transparent);
  cursor: pointer;
}

.xuanxin-fullpage-lightbox-stage {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  max-width: 96vw;
  max-height: 96vh;
  pointer-events: none;
}

.xuanxin-fullpage-lightbox-img {
  max-width: min(96vw, 96vh);
  max-height: min(96vw, 96vh);
  width: auto;
  height: auto;
  object-fit: contain;
  border-radius: var(--radius-sm);
  box-shadow: 0 16px 48px rgba(15, 23, 42, 0.45);
  transition: transform 0.35s ease;
  pointer-events: auto;
}

.xuanxin-fullpage-lightbox-img.is-rotated-side {
  max-width: min(96vh, 96vw);
  max-height: min(96vw, 96vh);
}

.xuanxin-fullpage-lightbox-close {
  position: absolute;
  top: -0.35rem;
  right: -0.35rem;
  width: 2.2rem;
  height: 2.2rem;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  background: var(--color-surface);
  color: var(--color-text);
  font-size: 1.35rem;
  line-height: 1;
  cursor: pointer;
  pointer-events: auto;
  box-shadow: 0 4px 16px var(--color-shadow);
}

.xuanxin-fullpage-lightbox-close:hover,
.xuanxin-fullpage-lightbox-close:focus-visible {
  color: #fff;
  background: var(--color-primary);
  border-color: var(--color-primary);
  outline: none;
}

body.xuanxin-lightbox-open {
  overflow: hidden;
}

/* Book figures: no hover chrome (shadow/border) */
body.bubble-book-page .prose img,
body.bubble-book-page .prose img:hover,
body.bubble-book-page .prose figure.image-block img,
body.bubble-book-page .prose figure.image-block img:hover {
  box-shadow: none;
  outline: none;
}

/* Image utility classes (from MockSphere) */
.prose .img-small { width: 200px !important; max-width: 200px !important; }
.prose .img-medium { width: 400px !important; max-width: 400px !important; }
.prose .img-large { width: 600px !important; max-width: 600px !important; }
.prose .img-full { width: 100% !important; }
.prose .img-left { float: left; margin: 0 1.25rem 1rem 0; }
.prose .img-right { float: right; margin: 0 0 1rem 1.25rem; }
.prose .img-center { display: block; margin: 1.25rem auto; }
.prose .img-rounded { border-radius: 15px; }
.prose .img-circle { border-radius: 50%; }
.prose .img-border { border: 2px solid var(--color-border); }
.prose .img-border-primary { border: 2px solid var(--color-primary); }

.prose hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: 2rem 0;
}

.prose .toc {
  background: var(--color-blockquote-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1rem 1.5rem;
  margin: 1.5rem 0;
  font-family: var(--font-sans);
  font-size: 0.9rem;
}

.prose .toc ul { margin: 0; padding-left: 1.2rem; }

/* Video embeds */
.video-embed, .youtube-embed-container {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  overflow: hidden;
  max-width: 100%;
  margin: 1.5rem 0;
  border-radius: var(--radius);
  box-shadow: 0 4px 16px var(--color-shadow);
}

.video-embed iframe, .youtube-embed-container iframe {
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 100%;
  border: 0;
  border-radius: var(--radius);
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--color-border);
  padding: 2rem 0;
  text-align: center;
  color: var(--color-text-muted);
  font-size: 0.85rem;
}

.site-footer a { color: var(--color-primary); }

/* Opt-in custom footer branding (peanut.config's html_footer_logo/_text/
   _link) in place of the default "Built with peanutbook" line -- see
   HtmlBookRenderer._book_header_context. Explicit width/height on the
   <img> itself (not just this CSS) keeps it small regardless of
   stylesheet load order; this CSS is what actually renders it at that
   size once the sheet's applied. */
.site-footer-brand { margin: 0; }
.site-footer-brand-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: inherit;
  text-decoration: none;
}
.site-footer-brand-link:hover { text-decoration: underline; }
.site-footer-logo {
  width: 20px;
  height: 20px;
  max-width: 20px;
  max-height: 20px;
  object-fit: contain;
  flex-shrink: 0;
}

/* Foldable left sidebar — in-chapter section navigation (H2 jump links) */
.bubble-section-sidebar {
  position: fixed;
  left: 0;
  top: 4.65rem;
  z-index: 300;
  display: flex;
  align-items: stretch;
  max-height: calc(100vh - 5.25rem);
  font-family: var(--font-sans);
  filter: drop-shadow(0 8px 24px color-mix(in srgb, var(--color-shadow) 80%, transparent));
  pointer-events: none;
}

.bubble-section-sidebar > * {
  pointer-events: auto;
}

.bubble-section-sidebar-handle {
  flex: 0 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  width: 2.65rem;
  padding: 0.75rem 0.35rem;
  border: 1px solid var(--color-border);
  border-left: none;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  background: linear-gradient(
    180deg,
    color-mix(in srgb, var(--color-primary) 12%, var(--color-surface)),
    var(--color-surface)
  );
  color: var(--color-primary);
  cursor: pointer;
  transition: background 0.18s ease, color 0.18s ease, box-shadow 0.18s ease;
}

.bubble-section-sidebar-handle:hover,
.bubble-section-sidebar-handle:focus-visible {
  background: color-mix(in srgb, var(--color-primary) 16%, var(--color-surface));
  color: var(--color-primary-hover);
  outline: none;
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--color-primary) 25%, transparent);
}

.bubble-section-sidebar-handle-icon {
  display: flex;
  line-height: 0;
}

.bubble-section-sidebar-handle-text {
  font-size: 0.62rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  writing-mode: vertical-rl;
  transform: rotate(180deg);
}

.bubble-section-sidebar-panel {
  width: 14.5rem;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  border: 1px solid var(--color-border);
  border-left: none;
  border-radius: 0 var(--radius) var(--radius) 0;
  background: color-mix(in srgb, var(--color-surface) 98%, transparent);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  transition: width 0.24s cubic-bezier(0.4, 0, 0.2, 1),
    opacity 0.18s ease,
    border-color 0.18s ease;
}

.bubble-section-sidebar.is-collapsed .bubble-section-sidebar-panel {
  width: 0;
  opacity: 0;
  border-color: transparent;
  pointer-events: none;
}

.bubble-section-sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  padding: 0.65rem 0.85rem 0.55rem;
  border-bottom: 1px solid var(--color-border);
  background: color-mix(in srgb, var(--color-primary) 5%, var(--color-surface));
}

.bubble-section-sidebar-title {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--color-text-muted);
}

.bubble-section-sidebar-count {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 1.35rem;
  height: 1.35rem;
  padding: 0 0.35rem;
  border-radius: 999px;
  font-size: 0.68rem;
  font-weight: 700;
  color: var(--color-primary);
  background: color-mix(in srgb, var(--color-primary) 12%, transparent);
}

.bubble-section-sidebar-nav {
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: 0.45rem 0.35rem 0.55rem;
  scrollbar-width: thin;
  scrollbar-color: color-mix(in srgb, var(--color-primary) 35%, transparent) transparent;
}

.bubble-section-sidebar-nav ol {
  list-style: none;
  margin: 0;
  padding: 0;
}

.bubble-section-sidebar-item + .bubble-section-sidebar-item {
  margin-top: 0.15rem;
}

.bubble-section-sidebar-link {
  display: flex;
  align-items: flex-start;
  gap: 0.55rem;
  padding: 0.45rem 0.55rem;
  border-radius: var(--radius-sm);
  text-decoration: none;
  color: var(--color-text);
  transition: background 0.15s ease, color 0.15s ease, transform 0.12s ease;
}

.bubble-section-sidebar-link:hover,
.bubble-section-sidebar-link:focus-visible {
  background: color-mix(in srgb, var(--color-primary) 9%, transparent);
  color: var(--color-primary);
  outline: none;
}

.bubble-section-sidebar-link.is-active {
  background: color-mix(in srgb, var(--color-primary) 13%, transparent);
  color: var(--color-primary);
  box-shadow: inset 3px 0 0 var(--color-primary);
}

.bubble-section-sidebar-num {
  flex: 0 0 auto;
  min-width: 1.35rem;
  font-size: 0.68rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  line-height: 1.35;
  color: var(--color-text-muted);
}

.bubble-section-sidebar-link.is-active .bubble-section-sidebar-num,
.bubble-section-sidebar-link:hover .bubble-section-sidebar-num {
  color: var(--color-primary);
}

.bubble-section-sidebar-label {
  flex: 1;
  font-size: 0.78rem;
  line-height: 1.35;
  font-weight: 500;
}

@media (max-width: 900px) {
  .bubble-section-sidebar {
    top: 4.35rem;
    max-height: calc(100vh - 4.75rem);
  }

  .bubble-section-sidebar-panel {
    width: min(14.5rem, calc(100vw - 3.5rem));
  }
}

@media print {
  .bubble-section-sidebar {
    display: none !important;
  }
}

/* Legacy inline section buttons (kept for older HTML output) */
.xuanxin-section-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  justify-content: center;
  margin: 0.75rem 0 1.35rem;
}

.xuanxin-section-nav--floating {
  position: fixed;
  right: max(1rem, env(safe-area-inset-right, 0px));
  bottom: calc(1rem + env(safe-area-inset-bottom, 0px));
  left: auto;
  z-index: 250;
  margin: 0;
  padding: 0.45rem 0.55rem;
  max-width: min(22rem, calc(100vw - 2rem));
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 0.4rem;
  background: color-mix(in srgb, var(--color-surface) 96%, transparent);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: 0 4px 20px var(--color-shadow);
}

.xuanxin-section-nav--floating .xuanxin-section-nav-btn {
  padding: 0.32rem 0.75rem;
  font-size: 0.82rem;
}

body.xuanxin-has-section-nav {
  padding-bottom: 0;
}

body.xuanxin-has-section-nav .site-footer {
  margin-bottom: 0;
}

.xuanxin-section-nav-btn {
  display: inline-block;
  padding: 0.38rem 0.95rem;
  font-family: var(--font-sans);
  font-size: 0.88rem;
  font-weight: 500;
  font-style: normal;
  line-height: 1.3;
  text-decoration: none;
  color: var(--color-primary);
  background: var(--color-surface);
  border: 1px solid color-mix(in srgb, var(--color-primary) 35%, var(--color-border));
  border-radius: 999px;
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease,
    box-shadow 0.15s ease;
}

.xuanxin-section-nav-btn:hover,
.xuanxin-section-nav-btn:focus-visible {
  color: #fff;
  background: var(--color-primary);
  border-color: var(--color-primary);
  box-shadow: 0 2px 8px color-mix(in srgb, var(--color-primary) 35%, transparent);
  outline: none;
}

.prose h2.xuanxin-section-target {
  animation: xuanxin-section-flash 1.6s ease;
}

@keyframes xuanxin-section-flash {
  0%, 100% { background: transparent; }
  18% { background: color-mix(in srgb, var(--color-primary) 14%, transparent); }
  45% { background: color-mix(in srgb, var(--color-primary) 8%, transparent); }
}

/* Book table of contents */
.book-toc { margin: 0; }
.book-toc-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.55rem;
}
.book-toc-item a {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  min-height: 100%;
  padding: 0.8rem 1rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  color: var(--color-text);
  text-decoration: none;
  transition: border-color 0.15s, box-shadow 0.15s, transform 0.15s;
}
.book-toc-label {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--color-primary);
  line-height: 1.2;
}
.book-toc-title {
  font-size: 0.94rem;
  line-height: 1.35;
}
.book-toc-item a:hover {
  border-color: color-mix(in srgb, var(--color-primary) 45%, var(--color-border));
  box-shadow: 0 4px 14px var(--color-shadow);
  transform: translateY(-1px);
}

.diary-day-nav {
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid color-mix(in srgb, var(--color-border, #cbd5e1) 80%, transparent);
}

/* Chapter prev/next navigation */
.chapter-nav {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 0.75rem;
  margin: 1.5rem 0;
  font-size: 0.92rem;
}
.chapter-nav-top { margin-top: 0.5rem; }
.chapter-nav-bottom { margin-bottom: 2rem; }
.chapter-nav-prev,
.chapter-nav-next {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.5rem 1rem;
  border-radius: 999px;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-primary);
  text-decoration: none;
  line-height: 1.35;
  transition: background-color 0.15s ease, border-color 0.15s ease, box-shadow 0.15s ease;
}
.chapter-nav-prev:hover,
.chapter-nav-next:hover {
  text-decoration: none;
  border-color: var(--color-primary);
  background: color-mix(in srgb, var(--color-primary) 10%, var(--color-surface));
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
}
.chapter-nav-prev { justify-self: start; text-align: left; }
.chapter-nav-next { justify-self: end; text-align: right; }
/* section_pages (booksite's Django app) blanks this out with an empty
   <span class="chapter-nav-prev/next"> at a chapter's actual first/last
   section, keeping the grid cell for alignment -- without this, the pill
   border/background would still show as a visible empty box. */
.chapter-nav-prev:empty, .chapter-nav-next:empty {
  border-color: transparent;
  background: transparent;
}
.chapter-nav-index {
  justify-self: center;
  color: var(--color-text-muted);
  text-decoration: none;
  white-space: nowrap;
}
.chapter-nav-index:hover { color: var(--color-primary); }
.chapter-nav-spacer { display: block; }

@media (max-width: 640px) {
  html { font-size: 16px; }
  .post { padding: 1.5rem 1.25rem; margin: 1rem auto 2rem; }
  .post-title { font-size: 1.7rem; }
  .index-hero h1,
  .book-home-title { font-size: 1.75rem; }
  .book-home-hero {
    padding: 1.75rem 0 2.25rem;
  }
  .book-home-hero-inner {
    text-align: center;
  }
  .book-home-intro {
    align-items: center;
  }
  .book-home-desc {
    text-align: center;
  }
  .book-cover {
    max-width: min(260px, 72vw);
  }
  .chapter-nav {
    grid-template-columns: 1fr;
    text-align: center;
  }
  .chapter-nav-prev,
  .chapter-nav-next { justify-self: center; text-align: center; }
  .chapter-nav-index { order: -1; margin-bottom: 0.25rem; }
  .page-nav {
    grid-template-columns: 1fr;
    text-align: center;
  }
  .page-nav-prev,
  .page-nav-next { justify-self: center; }
  .page-nav-indicator { order: -1; margin-bottom: 0.25rem; }
}

/* Cross-references */
.prose a.bubble-ref {
  color: var(--color-primary);
  text-decoration: none;
  border-bottom: 1px dotted color-mix(in srgb, var(--color-primary) 55%, transparent);
  white-space: nowrap;
}

.prose a.bubble-ref:hover {
  border-bottom-style: solid;
}

/* Algorithm blocks */
.prose .bubble-algorithm {
  margin: 1.25rem 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
  overflow: hidden;
}

.prose .bubble-alg-caption {
  padding: 0.65rem 1rem;
  font-weight: 600;
  font-size: 0.92rem;
  border-bottom: 1px solid var(--color-border);
  background: color-mix(in srgb, var(--color-blockquote-bg) 70%, var(--color-surface));
}

.prose .bubble-alg-body {
  padding: 0.75rem 1rem 0.85rem;
  font-family: var(--font-mono, ui-monospace, monospace);
  font-size: 0.82rem;
  line-height: 1.55;
}

.prose .bubble-alg-line {
  margin: 0.15rem 0;
}

.prose .bubble-alg-kw {
  font-weight: 700;
  font-variant: small-caps;
  letter-spacing: 0.03em;
}

.prose .bubble-alg-comment {
  color: var(--color-text-muted);
  font-style: italic;
  margin-left: 0.35rem;
}

.prose .bubble-alg-for em,
.prose .bubble-alg-state em {
  font-style: normal;
  font-weight: 600;
  color: var(--color-primary);
}

/* Fancy dividers (LaTeX \\fancydivider / \\fancydividerwithicon) */
.prose .bubble-fancy-divider {
  display: flex;
  align-items: center;
  width: var(--bubble-divider-width, 95%);
  max-width: 100%;
  margin: 1.5rem auto;
  clear: both;
}

.prose .bubble-fancy-divider-line {
  flex: 1 1 auto;
  height: 0;
  border-top: 1.5px solid var(--bubble-divider-color, #99ccff);
  min-width: 1.5rem;
}

.prose .bubble-fancy-divider-icon {
  flex: 0 0 auto;
  height: 1.75rem;
  width: auto;
  margin: 0 0.4rem;
  object-fit: contain;
}

.prose .bubble-fancy-divider-end .bubble-fancy-divider-line-after,
.prose .bubble-fancy-divider-begin .bubble-fancy-divider-line-before {
  display: none;
}

.prose .bubble-fancy-divider-plain .bubble-fancy-divider-line {
  flex: none;
  width: 100%;
}

/* Numbered display equations */
.prose .math-display.bubble-equation {
  position: relative;
  padding-right: 3.25rem;
}

.prose .bubble-equation-number {
  position: absolute;
  right: 0;
  top: 50%;
  transform: translateY(-50%);
  font-size: 0.88rem;
  color: var(--color-text-muted);
  font-family: var(--font-sans);
  white-space: nowrap;
}

/* Raw \begin{center}...\end{center} LaTeX (print-only colophon/closing
   pages) converted to this by htmlbook/latex_decorations.py, so it needs
   an HTML equivalent of what \begin{center} does. */
.prose .latex-center {
  text-align: center;
  margin: 1.5em 0;
}