/* ============================================================
   Knowledge Base Design System
   ============================================================ */

/* --- Design Tokens --- */
:root {
  --bg: #faf9f7;
  --surface: #f3f2ef;
  --text: #1c1917;
  --text-secondary: #44403c;
  --muted: #78716c;
  --accent: #2563eb;
  --border: #e7e5e4;
  --border-light: #f0efed;
  --hover-bg: #f5f5f3;

  /* Section colors */
  --papers: #7c3aed;
  --notes: #0891b2;
  --log: #ea580c;
  --todo: #16a34a;
  --blogs: #2563eb;
  --research: #e11d48;

  /* Typography */
  --font-body: 'Open Sans', 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;
  --font-size-sm: 0.8125rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.5rem;
  --font-size-2xl: 2rem;
  --line-height: 1.7;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;

  /* Layout */
  --max-content: 860px;
  --max-page: 1200px;
  --nav-height: 52px;
  --toc-width: 220px;
  --notes-width: 200px;

  /* Callout colors */
  --callout-note: #2563eb;
  --callout-warning: #d97706;
  --callout-tip: #16a34a;
  --callout-important: #dc2626;
  --callout-example: #7c3aed;
}

/* --- Reset & Base --- */
*, *::before, *::after {
  box-sizing: border-box;
}

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

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.15s ease;
}

a:hover {
  text-decoration: underline;
}

h1, h2, h3, h4, h5, h6 {
  line-height: 1.3;
  margin-top: var(--space-xl);
  margin-bottom: var(--space-md);
  font-weight: 600;
}

h1 { font-size: var(--font-size-2xl); }
h2 { font-size: var(--font-size-xl); }
h3 { font-size: var(--font-size-lg); }

p { margin: 0 0 var(--space-md) 0; }

hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: var(--space-xl) 0;
}

blockquote {
  border-left: 3px solid var(--accent);
  background: var(--surface);
  margin: var(--space-md) 0;
  padding: var(--space-sm) var(--space-lg);
  color: var(--text-secondary);
  border-radius: 0 4px 4px 0;
}

blockquote p:last-child { margin-bottom: 0; }

/* --- Images (standard Markdown) --- */
article img,
.content-area img {
  max-width: 100%;
  height: auto;
  border-radius: 4px;
  display: block;
  margin: var(--space-md) auto;
}

/* --- Code --- */
code {
  background-color: #282c34;
  color: #dae0eb;
  font-family: var(--font-mono);
  font-size: 0.875em;
  border-radius: 4px;
  padding: 0.15em 0.4em;
  white-space: pre-wrap;
  word-wrap: break-word;
}

pre {
  background-color: #282c34;
  border-radius: 6px;
  padding: var(--space-md);
  overflow-x: auto;
  margin: var(--space-md) 0;
}

pre code {
  padding: 0;
  background: none;
  font-size: 0.875rem;
}

/* --- Tables --- */
table {
  width: 100%;
  margin-bottom: var(--space-md);
  border-collapse: collapse;
  font-size: 0.9375rem;
}

th, td {
  padding: 0.625rem 0.75rem;
  border: 1px solid var(--border);
  text-align: left;
}

th {
  background-color: var(--surface);
  font-weight: 600;
}

tr:nth-child(even) { background-color: var(--surface); }
tr:hover { background-color: var(--hover-bg); }

@media (max-width: 600px) {
  table { display: block; overflow-x: auto; }
}

/* ============================================================
   Navigation
   ============================================================ */

.site-nav {
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  padding: 0 var(--space-lg);
  height: var(--nav-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 100;
}

.site-nav__left {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}

.site-nav__title {
  font-size: var(--font-size-lg);
  font-weight: 700;
  color: var(--text);
  text-decoration: none;
  white-space: nowrap;
}

.site-nav__title:hover {
  text-decoration: none;
  color: var(--text);
}

.site-nav__links {
  list-style: none;
  display: flex;
  gap: var(--space-md);
  margin: 0;
  padding: 0;
}

.nav-link {
  color: var(--muted);
  font-size: var(--font-size-sm);
  font-weight: 500;
  text-decoration: none;
  padding: var(--space-xs) var(--space-sm);
  border-radius: 4px;
  transition: color 0.15s, background 0.15s;
}

.nav-link:hover {
  color: var(--text);
  background: var(--surface);
  text-decoration: none;
}

.nav-link--active {
  color: var(--text);
  font-weight: 600;
  border-bottom: 2px solid var(--accent);
}

.site-nav__right {
  display: flex;
  align-items: center;
}

.search-trigger {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: var(--space-xs) var(--space-md);
  font-size: var(--font-size-sm);
  color: var(--muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  transition: border-color 0.15s;
}

.search-trigger:hover {
  border-color: var(--muted);
}

.search-trigger kbd {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 0 4px;
  font-size: 0.75rem;
  font-family: var(--font-body);
}

/* ============================================================
   Search Overlay
   ============================================================ */

.search-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.4);
  z-index: 200;
  justify-content: center;
  padding-top: 15vh;
}

.search-overlay.active {
  display: flex;
}

.search-box {
  background: var(--bg);
  border-radius: 12px;
  width: 90%;
  max-width: 560px;
  max-height: 60vh;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  box-shadow: 0 16px 48px rgba(0, 0, 0, 0.15);
}

.search-input {
  width: 100%;
  padding: var(--space-md) var(--space-lg);
  border: none;
  border-bottom: 1px solid var(--border);
  font-size: var(--font-size-lg);
  font-family: var(--font-body);
  background: transparent;
  color: var(--text);
  outline: none;
}

.search-results {
  overflow-y: auto;
  padding: var(--space-sm);
}

.search-result {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  padding-left: var(--space-lg);
  border-radius: 6px;
  border-left: 3px solid transparent;
  text-decoration: none;
  color: var(--text);
  transition: background 0.1s;
}

.search-result:hover,
.search-result.selected {
  background: var(--surface);
  text-decoration: none;
}

.search-result__title {
  font-weight: 500;
  flex: 1;
}

.search-result__meta {
  font-size: var(--font-size-sm);
  color: var(--muted);
}

.search-no-results {
  padding: var(--space-lg);
  text-align: center;
  color: var(--muted);
}

/* ============================================================
   Section Color Indicators
   ============================================================ */

.section-dot {
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
}

.section-dot--papers { background: var(--papers); }
.section-dot--notes { background: var(--notes); }
.section-dot--log { background: var(--log); }
.section-dot--to-do { background: var(--todo); }
.section-dot--blogs { background: var(--blogs); }
.section-dot--research { background: var(--research); }

.section-border--papers { border-left: 3px solid var(--papers) !important; }
.section-border--notes { border-left: 3px solid var(--notes) !important; }
.section-border--log { border-left: 3px solid var(--log) !important; }
.section-border--to-do { border-left: 3px solid var(--todo) !important; }
.section-border--blogs { border-left: 3px solid var(--blogs) !important; }
.section-border--research { border-left: 3px solid var(--research) !important; }

/* ============================================================
   Tag Pills
   ============================================================ */

.tag-pill {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 500;
  padding: 1px 8px;
  border-radius: 9999px;
  background: var(--surface);
  color: var(--muted);
  text-decoration: none;
  transition: background 0.15s, color 0.15s;
  white-space: nowrap;
}

.tag-pill:hover {
  background: var(--border);
  color: var(--text);
  text-decoration: none;
}

.tag-pills {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
}

/* ============================================================
   Dashboard (Homepage)
   ============================================================ */

.dashboard {
  max-width: var(--max-page);
  margin: 0 auto;
  padding: var(--space-xl) var(--space-lg);
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: var(--space-2xl);
}

.dashboard h2 {
  font-size: var(--font-size-lg);
  margin-top: 0;
  margin-bottom: var(--space-md);
  color: var(--text);
}

.recent-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.recent-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  padding-left: var(--space-lg);
  border-bottom: 1px solid var(--border-light);
  border-left: 3px solid transparent;
}

.recent-item:last-child { border-bottom: none; }

.recent-item__body {
  flex: 1;
  min-width: 0;
}

.recent-item__title {
  font-weight: 500;
  color: var(--text);
  text-decoration: none;
  display: block;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.recent-item__title:hover {
  color: var(--accent);
  text-decoration: none;
}

.recent-item__date {
  font-size: var(--font-size-sm);
  color: var(--muted);
}

.sidebar-section {
  margin-bottom: var(--space-xl);
}

.quick-nav {
  list-style: none;
  padding: 0;
  margin: 0;
}

.quick-nav li {
  margin-bottom: var(--space-sm);
}

.quick-nav a {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  color: var(--text);
  text-decoration: none;
  font-weight: 500;
  padding: var(--space-xs) var(--space-sm);
  padding-left: var(--space-md);
  border-radius: 4px;
  border-left: 3px solid transparent;
  transition: background 0.15s;
}

.quick-nav a:hover {
  background: var(--surface);
  text-decoration: none;
}

.quick-nav__count {
  color: var(--muted);
  font-size: var(--font-size-sm);
  margin-left: auto;
}

.tag-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
}

@media (max-width: 768px) {
  .dashboard {
    grid-template-columns: 1fr;
  }
}

/* ============================================================
   List Pages
   ============================================================ */

.list-header {
  max-width: var(--max-page);
  margin: 0 auto;
  padding: var(--space-xl) var(--space-lg) var(--space-md);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-md);
}

.list-header h1 {
  margin: 0;
  font-size: var(--font-size-xl);
}

.list-header__count {
  color: var(--muted);
  font-size: var(--font-size-sm);
  font-weight: 400;
}

.list-controls {
  display: flex;
  gap: var(--space-sm);
  align-items: center;
}

.list-controls button {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: var(--space-xs) var(--space-md);
  font-size: var(--font-size-sm);
  color: var(--muted);
  cursor: pointer;
  font-family: var(--font-body);
  transition: border-color 0.15s, color 0.15s;
}

.list-controls button:hover {
  border-color: var(--muted);
  color: var(--text);
}

.list-controls button.active {
  background: var(--text);
  color: var(--bg);
  border-color: var(--text);
}

.list-filter-bar {
  max-width: var(--max-page);
  margin: 0 auto;
  padding: 0 var(--space-lg) var(--space-md);
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
}

.filter-pill {
  font-size: 0.75rem;
  padding: 2px 10px;
  border-radius: 9999px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  font-family: var(--font-body);
  transition: all 0.15s;
}

.filter-pill:hover {
  border-color: var(--muted);
  color: var(--text);
}

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

.page-list {
  max-width: var(--max-page);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  list-style: none;
}

.page-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-md);
  padding: var(--space-md) var(--space-md);
  padding-left: var(--space-lg);
  border-bottom: 1px solid var(--border-light);
  border-left: 3px solid transparent;
  transition: background 0.1s;
}

.page-item:hover {
  background: var(--hover-bg);
}

.page-item__body {
  flex: 1;
  min-width: 0;
}

.page-item__title {
  font-weight: 600;
  color: var(--text);
  text-decoration: none;
  display: block;
}

.page-item__title:hover {
  color: var(--accent);
  text-decoration: none;
}

.page-item__subtitle {
  color: var(--muted);
  font-size: var(--font-size-sm);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  margin-top: 2px;
}

.page-item__meta {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  margin-top: var(--space-xs);
}

.page-item__date {
  font-size: var(--font-size-sm);
  color: var(--muted);
  white-space: nowrap;
  margin-left: auto;
  flex-shrink: 0;
}

/* Grid view (toggle) */
.page-list.grid-view {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-md);
}

.grid-view .page-item {
  flex-direction: column;
  border: 1px solid var(--border);
  border-radius: 8px;
  border-left: 3px solid transparent;
  padding: var(--space-md);
}

.grid-view .page-item__date {
  margin-left: 0;
}

/* ============================================================
   Breadcrumbs
   ============================================================ */

.breadcrumbs {
  font-size: var(--font-size-sm);
  color: var(--muted);
  margin-bottom: var(--space-sm);
  text-align: left;
}

.breadcrumbs a {
  color: var(--muted);
  text-decoration: none;
}

.breadcrumbs a:hover {
  color: var(--accent);
}

.breadcrumbs span {
  margin: 0 var(--space-xs);
}

/* ============================================================
   Single Page (3-column layout)
   ============================================================ */

.page-nav {
  display: flex;
  align-items: center;
  padding: var(--space-sm) var(--space-lg);
  margin-bottom: var(--space-sm);
}

.page-nav__back {
  flex: 0 0 100px;
  text-align: center;
}

.page-nav__title {
  flex: 2;
  text-align: center;
}

.page-nav__title h1 {
  margin: 0;
  font-size: var(--font-size-2xl);
}

.page-nav__siblings {
  flex: 0 0 auto;
  display: flex;
  flex-direction: row;
  gap: var(--space-md);
  justify-content: center;
  white-space: nowrap;
}

.page-nav a {
  color: var(--muted);
  text-decoration: underline;
  font-weight: 500;
  transition: color 0.15s;
}

.page-nav a:hover {
  color: var(--text);
}

.three-col {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-lg);
  max-width: 100%;
}

.toc-sidebar {
  flex: 0 0 var(--toc-width);
  padding: var(--space-sm) var(--space-md);
  border-right: 1px solid var(--border);
  position: sticky;
  top: calc(var(--nav-height) + 16px);
  max-height: calc(100vh - var(--nav-height) - 32px);
  overflow-y: auto;
}

.toc-sidebar h3 {
  margin-top: 0;
  font-size: var(--font-size-sm);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
}

.toc-sidebar ul {
  list-style: none;
  padding-left: 0;
}

.content-area {
  flex: 1 1 500px;
  min-width: 0;
  padding: 0 var(--space-md);
}

.notes-sidebar {
  flex: 0 0 var(--notes-width);
  padding: var(--space-sm) var(--space-md);
  border-left: 1px solid var(--border);
}

/* When notes sidebar is hidden via JS, content area expands */
.content-area.expanded {
  max-width: none;
  flex: 1 1 0;
}

.notes-sidebar h3 {
  margin-top: 0;
  font-size: var(--font-size-sm);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
}

/* Page metadata */
.page-meta {
  color: var(--muted);
  font-size: var(--font-size-sm);
  margin-bottom: var(--space-lg);
}

.page-meta strong {
  color: var(--text-secondary);
}

.page-meta a {
  color: var(--muted);
  text-decoration: underline;
}

/* Responsive */
@media (max-width: 1200px) {
  .toc-sidebar, .notes-sidebar {
    flex: 0 0 200px;
  }
}

@media (max-width: 900px) {
  .content-area {
    flex: 1 1 100% !important;
    order: 1;
  }
  .toc-sidebar, .notes-sidebar {
    flex: 1 1 calc(50% - var(--space-lg)) !important;
    border: none !important;
    border-top: 1px solid var(--border) !important;
    position: static !important;
    max-height: none !important;
  }
  .notes-sidebar { order: 3; }
  .toc-sidebar { order: 2; }
  .page-nav__back, .page-nav__siblings { flex: 0 0 60px; }
}

/* ============================================================
   TOC Links
   ============================================================ */

.toc-link {
  color: var(--muted);
  text-decoration: none;
  font-size: var(--font-size-sm);
  transition: color 0.15s;
}

.toc-link:hover {
  color: var(--text);
  text-decoration: none;
}

.toc-link.active {
  font-weight: 600;
  color: var(--text);
}

.toc-item {
  margin-bottom: 6px;
}

.toc-h3 { margin-left: var(--space-lg); }
.toc-h4 { margin-left: calc(var(--space-lg) * 2); }

/* ============================================================
   Footnotes & Citations
   ============================================================ */

#footnote-container {
  position: relative;
}

.footnote-wrapper {
  position: absolute;
  left: 0;
  right: 0;
  padding: var(--space-xs) var(--space-sm);
  font-size: 0.875rem;
  background-color: var(--bg);
  border-radius: 4px;
  transition: background-color 0.15s, opacity 0.3s ease-out;
}

.footnote-wrapper.visible {
  opacity: 1;
}

.footnote-index {
  font-weight: 600;
  color: var(--muted);
  margin-right: var(--space-xs);
}

.footnote-content {
  display: inline;
  margin: 0;
}

.citation {
  color: var(--accent);
  text-decoration: none;
}

.citation:hover {
  text-decoration: underline;
}

.reference-index {
  margin-right: 0.5em;
  color: var(--muted);
}

.cited-by {
  margin-top: var(--space-xl);
  border-top: 1px solid var(--border);
  padding-top: var(--space-md);
}

.cited-by ul {
  list-style: none;
  padding-left: 0;
}

.cited-by li {
  margin-bottom: var(--space-md);
}

.cited-by .context-snippet {
  margin-top: var(--space-xs);
  padding: var(--space-sm);
  background: var(--surface);
  border-radius: 4px;
  font-size: 0.875rem;
}

/* ============================================================
   Stacked View
   ============================================================ */

.section-content {
  margin-bottom: var(--space-2xl);
  padding-bottom: var(--space-xl);
  border-bottom: 1px solid var(--border-light);
}

.section-content:last-child {
  border-bottom: none;
}

.page-header {
  margin-bottom: var(--space-lg);
}

.page-title-link {
  color: inherit;
  text-decoration: none;
  transition: color 0.15s;
}

.page-title-link:hover {
  color: var(--accent);
  text-decoration: none;
}

.page-header .page-meta {
  margin-top: var(--space-xs);
}

.downgraded-content h1 { font-size: 1.5em; }
.downgraded-content h2 { font-size: 1.3em; }
.downgraded-content h3 { font-size: 1.15em; }
.downgraded-content h4 { font-size: 1em; }
.downgraded-content h5 { font-size: 0.9em; }
.downgraded-content h6 { font-size: 0.85em; }

/* ============================================================
   Taxonomy / Tags Page
   ============================================================ */

.tag-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: var(--space-md);
  max-width: var(--max-page);
  margin: 0 auto;
  padding: var(--space-lg);
}

.tag-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-md);
  border: 1px solid var(--border);
  border-radius: 8px;
  text-decoration: none;
  color: var(--text);
  font-weight: 500;
  transition: border-color 0.15s, background 0.15s;
}

.tag-card:hover {
  border-color: var(--accent);
  background: var(--surface);
  text-decoration: none;
}

.tag-card__count {
  color: var(--muted);
  font-size: var(--font-size-sm);
}

/* ============================================================
   Figures & Media
   ============================================================ */

figure {
  margin: var(--space-lg) 0;
  text-align: center;
}

figure img {
  border-radius: 6px;
  display: block;
  margin: 0 auto;
}

figcaption {
  font-size: var(--font-size-sm);
  color: var(--muted);
  margin-top: var(--space-sm);
  font-style: italic;
}

.video-container {
  margin: var(--space-lg) 0;
}

.video-container video {
  max-width: 100%;
  height: auto;
  border-radius: 6px;
  display: block;
  margin: 0 auto;
}

/* YouTube responsive wrapper */
.youtube-container {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  overflow: hidden;
  margin: var(--space-lg) 0;
  border-radius: 6px;
}

.youtube-container iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

.pdf-container {
  margin: var(--space-md) 0;
}

.pdf-container iframe {
  border: none;
  width: 100%;
  border-radius: 4px;
}

/* ============================================================
   Callouts / Admonitions
   ============================================================ */

.callout {
  border-left: 4px solid var(--callout-note);
  background: var(--surface);
  border-radius: 0 6px 6px 0;
  padding: var(--space-md) var(--space-lg);
  margin: var(--space-md) 0;
}

.callout__header {
  font-weight: 600;
  margin-bottom: var(--space-sm);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.callout--note { border-left-color: var(--callout-note); }
.callout--note .callout__header { color: var(--callout-note); }
.callout--warning { border-left-color: var(--callout-warning); }
.callout--warning .callout__header { color: var(--callout-warning); }
.callout--tip { border-left-color: var(--callout-tip); }
.callout--tip .callout__header { color: var(--callout-tip); }
.callout--important { border-left-color: var(--callout-important); }
.callout--important .callout__header { color: var(--callout-important); }
.callout--example { border-left-color: var(--callout-example); }
.callout--example .callout__header { color: var(--callout-example); }

.callout p:last-child { margin-bottom: 0; }

/* ============================================================
   Math Blocks (Theorem, Proof, etc.)
   ============================================================ */

.math-block {
  border-left: 3px solid var(--border);
  padding: var(--space-md) var(--space-lg);
  margin: var(--space-md) 0;
  background: var(--surface);
  border-radius: 0 4px 4px 0;
}

.math-block__label {
  font-weight: 700;
  margin-bottom: var(--space-sm);
}

.math-block--theorem { border-left-color: var(--accent); }
.math-block--theorem .math-block__label { color: var(--accent); }
.math-block--definition { border-left-color: var(--notes); }
.math-block--definition .math-block__label { color: var(--notes); }
.math-block--lemma { border-left-color: var(--papers); }
.math-block--lemma .math-block__label { color: var(--papers); }

.proof-block {
  margin: var(--space-md) 0;
  padding: var(--space-md) var(--space-lg);
}

.proof-block__label {
  font-style: italic;
  font-weight: 600;
  margin-bottom: var(--space-sm);
}

.proof-block__qed {
  text-align: right;
  margin-top: var(--space-sm);
}

/* ============================================================
   Collapse / Toggle
   ============================================================ */

.collapse-toggle {
  cursor: pointer;
  display: inline-block;
  transition: transform 0.2s ease;
  margin-right: var(--space-xs);
  user-select: none;
}

.collapse-toggle.expanded {
  transform: rotate(90deg);
}

.expanded-content {
  margin-top: var(--space-sm);
  padding-left: var(--space-lg);
}

.hidden { display: none; }

/* ============================================================
   Plotly
   ============================================================ */

.plotly-container {
  width: 100%;
  overflow-x: auto;
  margin: var(--space-lg) 0;
}

/* ============================================================
   Edit Source Link
   ============================================================ */

.edit-source-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: var(--font-size-sm);
  color: var(--muted);
  text-decoration: none;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 3px 10px;
  transition: color 0.15s, border-color 0.15s, background 0.15s;
}

.edit-source-link:hover {
  color: var(--text);
  border-color: var(--muted);
  background: var(--hover-bg);
  text-decoration: none;
}

.edit-source-link kbd {
  font-family: var(--font-body);
  font-size: 0.7rem;
  color: var(--muted);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 0 4px;
}

/* ============================================================
   Papers Management Page
   ============================================================ */

.papers-search-bar {
  max-width: var(--max-page);
  margin: 0 auto;
  padding: 0 var(--space-lg) var(--space-md);
}

.papers-search-input {
  width: 100%;
  padding: var(--space-sm) var(--space-md);
  font-size: var(--font-size-base);
  font-family: var(--font-body);
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg);
  color: var(--text);
  outline: none;
  transition: border-color 0.15s;
}

.papers-search-input:focus {
  border-color: var(--accent);
}

.papers-search-input::placeholder {
  color: var(--muted);
}

.papers-filters {
  max-width: var(--max-page);
  margin: 0 auto;
  padding: 0 var(--space-lg) var(--space-sm);
}

.papers-filter-row {
  display: flex;
  align-items: flex-start;
  gap: var(--space-sm);
  margin-bottom: var(--space-xs);
}

.papers-filter-label {
  font-size: var(--font-size-sm);
  color: var(--muted);
  font-weight: 500;
  min-width: 52px;
  padding-top: 3px;
  flex-shrink: 0;
}

.papers-filter-pills {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
}

.papers-item__authors {
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
  margin-top: 2px;
}

.papers-item__journal {
  color: var(--muted);
  font-size: var(--font-size-sm);
  font-style: italic;
}

.papers-item__bibid {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--muted);
  background: var(--surface);
  padding: 1px 6px;
  border-radius: 4px;
}

/* ============================================================
   Export BibTeX Button
   ============================================================ */

.export-bib-btn {
  display: inline-block;
  margin-top: var(--space-lg);
  padding: var(--space-sm) var(--space-lg);
  font-size: var(--font-size-sm);
  font-family: var(--font-body);
  color: var(--text-secondary);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  cursor: pointer;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
}

.export-bib-btn:hover {
  background: var(--hover-bg);
  color: var(--text);
  border-color: var(--text-secondary);
}

/* ============================================================
   Footer
   ============================================================ */

.site-footer {
  border-top: 1px solid var(--border);
  padding: var(--space-lg);
  text-align: center;
  color: var(--muted);
  font-size: var(--font-size-sm);
  margin-top: var(--space-2xl);
}

/* ============================================================
   Progressive Loading Animations
   ============================================================ */

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

.toc-item {
  opacity: 0;
}

.toc-item.visible {
  animation: fadeIn 0.2s ease-out forwards;
}

.footnote-wrapper {
  opacity: 0;
}

.lazy-load {
  opacity: 0;
  transition: opacity 0.3s ease-out;
}

.lazy-load.loaded {
  opacity: 1;
}

/* ============================================================
   Export PDF Button
   ============================================================ */

.export-pdf-btn {
  display: inline-flex;
  align-items: center;
  font-size: var(--font-size-sm);
  color: var(--muted);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 3px 10px;
  margin-left: var(--space-xs);
  cursor: pointer;
  font-family: var(--font-body);
  transition: color 0.15s, border-color 0.15s, background 0.15s;
}

.export-pdf-btn:hover {
  color: var(--text);
  border-color: var(--muted);
  background: var(--hover-bg);
}

.export-pdf-btn:disabled {
  opacity: 0.7;
  cursor: wait;
}

/* ============================================================
   Client-side PDF Export
   ============================================================ */

/* PDF export styles removed — export now opens a self-styled window */

/* ============================================================
   Print Styles
   ============================================================ */

.print-only { display: none; }

@page {
  margin: 2cm;
}

@media print {
  .print-only { display: block !important; }

  .site-nav,
  .search-overlay,
  .breadcrumbs,
  .page-nav__back,
  .page-nav__siblings,
  .toc-sidebar,
  .notes-sidebar,
  .site-footer,
  .export-pdf-btn,
  .export-bib-btn,
  .edit-source-link,
  .tag-pills,
  .cited-by { display: none !important; }

  body {
    font-size: 11pt;
    line-height: 1.6;
    color: #000;
    background: #fff;
  }

  .page-nav {
    padding: 0;
    margin-bottom: 0.5em;
  }

  .page-nav__title {
    text-align: left;
    flex: 1;
  }

  .page-nav__title h1 {
    font-size: 1.6em;
    margin-bottom: 0.2em;
  }

  .three-col {
    display: block;
  }

  .content-area {
    max-width: 100% !important;
    padding: 0 !important;
    flex: none !important;
  }

  .footnotes[role="doc-endnotes"] { display: none !important; }

  /* Print TOC */
  .print-section-title {
    font-size: 1.15em;
    font-weight: 700;
    margin: 0 0 0.4em 0;
  }

  .print-toc-list {
    list-style: none;
    margin: 0 0 2em 0;
    padding: 0;
    border: 1px solid #ccc;
    padding: 0.8em 1.2em;
    border-radius: 4px;
  }

  .print-toc-h2 {
    margin-bottom: 0.2em;
    font-size: 0.95em;
  }

  .print-toc-h3 {
    margin-left: 1.8em;
    margin-bottom: 0.15em;
    font-size: 0.9em;
    color: #444;
  }

  /* Print footnotes */
  #print-footnotes hr {
    border: none;
    border-top: 1px solid #999;
    width: 30%;
    margin: 2.5em 0 0.8em 0;
  }

  .print-footnotes-list {
    padding-left: 1.5em;
    font-size: 0.85em;
    color: #333;
  }

  .print-footnotes-list li {
    margin-bottom: 0.35em;
  }

  /* Page break control */
  h2, h3 { page-break-after: avoid; }
  pre, blockquote, table, figure,
  .math-block, .callout, .proof-block { page-break-inside: avoid; }

  /* Links */
  a { color: #000 !important; text-decoration: none !important; }

  /* Code blocks */
  code {
    background-color: #f5f5f5 !important;
    color: #333 !important;
    border: 1px solid #ddd;
  }

  pre {
    background-color: #f5f5f5 !important;
    border: 1px solid #ddd;
  }

  pre code { border: none; }

  /* Images */
  img { max-width: 100% !important; }
}

/* ============================================================
   Responsive: Mobile Nav
   ============================================================ */

@media (max-width: 768px) {
  .site-nav {
    flex-wrap: wrap;
    height: auto;
    padding: var(--space-sm) var(--space-md);
    gap: var(--space-sm);
  }
  .site-nav__links {
    flex-wrap: wrap;
    gap: var(--space-xs);
  }
  .search-trigger kbd { display: none; }
}

/* ============================================================
   Graph Trigger (Nav)
   ============================================================ */

.graph-trigger {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: var(--space-xs) var(--space-md);
  font-size: var(--font-size-sm);
  color: var(--muted);
  text-decoration: none;
  transition: border-color 0.15s, color 0.15s;
}

.graph-trigger:hover {
  border-color: var(--muted);
  color: var(--text);
  text-decoration: none;
}

/* ============================================================
   Search Result Improvements
   ============================================================ */

.search-result {
  flex-wrap: wrap;
}

.search-result__title {
  flex: 1 1 100%;
}

.search-result__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 3px;
  margin-top: 2px;
}

.search-result__snippet {
  flex: 1 1 100%;
  font-size: 0.8rem;
  color: var(--muted);
  margin-top: 3px;
  line-height: 1.4;
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
  max-width: 100%;
}

.search-result.selected {
  background: var(--surface);
  outline: 2px solid var(--accent);
  outline-offset: -2px;
}

/* ============================================================
   Knowledge Graph Page
   ============================================================ */

.graph-page {
  max-width: 100%;
  padding: 0;
}

.graph-header {
  padding: var(--space-sm) var(--space-lg) var(--space-xs);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-xs);
}

.graph-header h1 {
  margin: 0;
  font-size: var(--font-size-xl);
  text-align: left;
  width: 100%;
}

.graph-controls {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  flex-wrap: wrap;
}

.graph-select {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: var(--space-xs) var(--space-sm);
  font-size: var(--font-size-sm);
  font-family: var(--font-body);
  color: var(--text);
  cursor: pointer;
}

.graph-search-input {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: var(--space-xs) var(--space-sm);
  font-size: var(--font-size-sm);
  font-family: var(--font-body);
  color: var(--text);
  width: 180px;
  outline: none;
}

.graph-search-input:focus {
  border-color: var(--accent);
}

.graph-toggle {
  font-size: var(--font-size-sm);
  color: var(--muted);
  display: flex;
  align-items: center;
  gap: 4px;
  cursor: pointer;
  user-select: none;
}

.graph-toggle input {
  cursor: pointer;
}

.graph-stats {
  padding: 0 var(--space-lg) var(--space-xs);
  font-size: var(--font-size-sm);
  color: var(--muted);
}

#graph-container {
  width: 100%;
  background: var(--bg);
  border-top: 1px solid var(--border);
}

#graph-container svg {
  display: block;
}

.graph-tooltip {
  display: none;
  position: absolute;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: var(--space-sm) var(--space-md);
  font-size: var(--font-size-sm);
  box-shadow: 0 4px 16px rgba(0,0,0,0.1);
  pointer-events: none;
  z-index: 300;
  max-width: 300px;
}

.graph-tooltip strong {
  display: block;
  margin-bottom: 2px;
}

.graph-tooltip span {
  color: var(--muted);
}

/* ============================================================
   Papers Table View
   ============================================================ */

.papers-table-wrap {
  max-width: var(--max-page);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  overflow-x: auto;
}

.papers-table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--font-size-sm);
}

.papers-table th {
  position: sticky;
  top: var(--nav-height);
  background: var(--surface);
  font-weight: 600;
  padding: var(--space-sm) var(--space-md);
  border-bottom: 2px solid var(--border);
  text-align: left;
  white-space: nowrap;
}

.papers-table__sortable {
  cursor: pointer;
  user-select: none;
  transition: color 0.15s;
}

.papers-table__sortable:hover {
  color: var(--accent);
}

/* ============================================================
   DAN Embedded Preview Mode
   ============================================================ */

html[data-dan-preview="1"] .site-nav,
html[data-dan-preview="1"] .site-footer,
html[data-dan-preview="1"] .search-overlay,
html[data-dan-preview="1"] .toc-sidebar,
html[data-dan-preview="1"] .notes-sidebar,
html[data-dan-preview="1"] .page-nav__back,
html[data-dan-preview="1"] .page-nav__siblings,
html[data-dan-preview="1"] .page-meta,
html[data-dan-preview="1"] .tag-pills,
html[data-dan-preview="1"] .edit-source-link,
html[data-dan-preview="1"] .export-pdf-btn,
html[data-dan-preview="1"] .export-bib-btn,
html[data-dan-preview="1"] #print-toc,
html[data-dan-preview="1"] #print-footnotes,
html[data-dan-preview="1"] .print-only,
html[data-dan-preview="1"] .footnotes[role="doc-endnotes"],
html[data-dan-preview="1"] #footnote-container {
  display: none !important;
}

html[data-dan-preview="1"] body {
  background: var(--bg);
}

html[data-dan-preview="1"] main {
  display: block;
  max-width: none;
  padding: 0;
}

html[data-dan-preview="1"] .breadcrumbs {
  display: none !important;
}

html[data-dan-preview="1"] .page-nav {
  align-items: flex-start;
  gap: 8px;
  padding: 16px 18px 8px;
  margin-bottom: 0;
}

html[data-dan-preview="1"] .page-nav__title {
  flex: 1 1 auto;
  min-width: 0;
  text-align: left;
}

html[data-dan-preview="1"] .page-nav__title h1 {
  font-size: clamp(1.55rem, 3.4vw, 2.15rem);
  line-height: 1.2;
}

html[data-dan-preview="1"] .three-col {
  display: block;
  max-width: none;
  gap: 0;
}

html[data-dan-preview="1"] .content-area,
html[data-dan-preview="1"] .content-area.expanded {
  display: block !important;
  flex: none !important;
  width: auto !important;
  max-width: none !important;
  min-width: 0 !important;
  padding: 0 18px 48px !important;
}

html[data-dan-preview="1"] #main-content > :first-child {
  margin-top: 0 !important;
}

.papers-table__sortable.sorted {
  color: var(--accent);
}

.papers-table__sortable::after {
  content: ' \2195';
  font-size: 0.7em;
  color: var(--muted);
}

.papers-table__sortable.sorted::after {
  color: var(--accent);
}

.papers-table td {
  padding: var(--space-sm) var(--space-md);
  border-bottom: 1px solid var(--border-light);
  vertical-align: top;
}

.papers-table tr:hover td {
  background: var(--hover-bg);
}

.papers-table td a {
  font-weight: 500;
}

.papers-table__authors {
  color: var(--text-secondary);
  max-width: 220px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.papers-table__journal {
  color: var(--muted);
  font-style: italic;
  white-space: nowrap;
}

.papers-table__date {
  color: var(--muted);
  white-space: nowrap;
}

/* ============================================================
   Summary Transclusion Shortcode
   ============================================================ */

.summary-transclusion {
  border-left: 3px solid var(--accent);
  background: var(--surface);
  border-radius: 0 6px 6px 0;
  padding: var(--space-md) var(--space-lg);
  margin: var(--space-md) 0;
}

.summary-transclusion__header {
  margin-bottom: var(--space-sm);
}

.summary-transclusion__header a {
  font-weight: 600;
}

.summary-transclusion__sub {
  color: var(--muted);
  font-size: var(--font-size-sm);
}

.summary-transclusion p:last-child {
  margin-bottom: 0;
}

.summary-transclusion--missing {
  color: var(--callout-warning);
  font-size: var(--font-size-sm);
}