/* ============================================
   Literature Vault — Design System & Styles
   ============================================ */

/* --- Design Tokens --- */
:root {
  /* Colors — Dark AI-Inspired Palette */
  --color-bg: #0a0e1a;
  --color-surface: #111827;
  --color-surface-hover: #1e293b;
  --color-border: rgba(99, 102, 241, 0.15);
  --color-text: #e2e8f0;
  --color-text-secondary: #94a3b8;
  --color-muted: #64748b;
  --color-accent: #818cf8;
  --color-accent-hover: #6366f1;
  --color-accent-light: rgba(99, 102, 241, 0.12);
  --color-accent-subtle: rgba(99, 102, 241, 0.08);
  --color-accent-border: rgba(99, 102, 241, 0.3);
  --color-accent-text: #ffffff;
  --color-success: #34d399;
  --color-warning: #fbbf24;
  --color-danger: #f87171;
  --color-code-bg: #0d1117;
  --color-code-text: #c9d1d9;

  /* Glow & Gradients */
  --color-glow: rgba(129, 140, 248, 0.25);
  --gradient-accent: linear-gradient(135deg, #6366f1, #8b5cf6, #a78bfa);
  --gradient-surface: linear-gradient(180deg, #141b2d, #0a0e1a);

  /* Typography */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-heading: 'Outfit', 'Inter', sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.8125rem;
  --font-size-base: 0.9375rem;
  --font-size-md: 1.0625rem;
  --font-size-lg: 1.25rem;
  --font-size-xl: 1.5rem;
  --font-size-2xl: 2rem;
  --line-height: 1.6;

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

  /* Layout */
  --sidebar-width: 260px;
  --content-max-width: 960px;
  --radius: 10px;
  --radius-sm: 6px;
  --radius-lg: 14px;
  --radius-pill: 9999px;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.2);
  --shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.4);

  /* Transitions */
  --transition: 180ms ease;
  --transition-slow: 300ms ease;
}

/* --- Reset & Base --- */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: var(--line-height);
  color: var(--color-text);
  background: var(--color-bg);
  min-height: 100vh;
  display: flex;
}

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

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

h1,
h2,
h3,
h4 {
  font-family: var(--font-heading);
  line-height: 1.3;
  font-weight: 600;
}

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

h2 {
  font-size: var(--font-size-xl);
}

h3 {
  font-size: var(--font-size-lg);
}

/* --- Layout --- */
.sidebar {
  width: var(--sidebar-width);
  background: var(--gradient-surface);
  border-right: 1px solid var(--color-border);
  padding: var(--space-xl);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 100;
  transition: transform var(--transition-slow);
}

.sidebar-brand {
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-lg);
  border-bottom: 1px solid var(--color-border);
}

.sidebar-brand h1 {
  font-size: var(--font-size-lg);
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.02em;
}

.sidebar-brand p {
  font-size: var(--font-size-xs);
  color: var(--color-muted);
  margin-top: var(--space-xs);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.sidebar-nav {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.sidebar-nav a {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  font-weight: 500;
  transition: all var(--transition);
}

.sidebar-nav a:hover {
  background: var(--color-surface-hover);
  color: var(--color-text);
}

.sidebar-nav a.active {
  background: var(--color-accent-light);
  color: var(--color-accent);
  box-shadow: inset 3px 0 0 var(--color-accent);
}

.sidebar-nav .nav-icon {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
  opacity: 0.7;
}

.sidebar-nav a.active .nav-icon {
  opacity: 1;
}

.sidebar-footer {
  margin-top: auto;
  padding-top: var(--space-lg);
  border-top: 1px solid var(--color-border);
  font-size: var(--font-size-xs);
  color: var(--color-muted);
  text-align: center;
}

.main-content {
  margin-left: var(--sidebar-width);
  flex: 1;
  min-height: 100vh;
}

.content-header {
  padding: var(--space-lg) var(--space-xl);
  border-bottom: 1px solid var(--color-border);
  background: var(--color-surface);
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-lg);
}

.content-header h2 {
  font-size: var(--font-size-lg);
  font-weight: 600;
  white-space: nowrap;
}

.content-body {
  padding: var(--space-xl);
}

/* --- Search Bar --- */
.search-bar {
  flex: 1;
  max-width: 480px;
  position: relative;
}

.search-bar input {
  width: 100%;
  padding: var(--space-sm) var(--space-md);
  padding-left: 2.5rem;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-family: var(--font-family);
  font-size: var(--font-size-sm);
  color: var(--color-text);
  transition: all var(--transition);
  outline: none;
}

.search-bar input:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px var(--color-accent-light);
  background: var(--color-surface);
}

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

.search-bar .search-icon {
  position: absolute;
  left: var(--space-md);
  top: 50%;
  transform: translateY(-50%);
  width: 16px;
  height: 16px;
  color: var(--color-muted);
  pointer-events: none;
}

/* --- Cards --- */
.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-lg);
  transition: all var(--transition);
  cursor: pointer;
}

.card:hover {
  box-shadow: 0 0 20px var(--color-glow), var(--shadow);
  border-color: var(--color-accent);
  transform: translateY(-2px);
}

.card-title {
  font-size: var(--font-size-md);
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--space-xs);
}

.card-meta {
  font-size: var(--font-size-xs);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-md);
}

.card-meta span+span::before {
  content: '·';
  margin: 0 var(--space-sm);
  color: var(--color-muted);
}

.card-summary {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  line-height: 1.5;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
  margin-top: var(--space-md);
}

.cards-grid {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

/* --- Paper Detail --- */
.paper-detail {
  animation: fadeIn var(--transition-slow);
}

.paper-detail .back-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-lg);
  transition: color var(--transition);
}

.paper-detail .back-link:hover {
  color: var(--color-accent);
}

.paper-detail h1 {
  font-size: var(--font-size-xl);
  margin-bottom: var(--space-sm);
}

.paper-external-link {
  display: inline-flex;
  align-items: center;
  vertical-align: middle;
  margin-left: var(--space-sm);
  color: var(--color-muted);
  transition: color var(--transition);
}

.paper-external-link:hover {
  color: var(--color-accent);
}

.paper-external-link svg {
  display: block;
}

.paper-detail .markdown-body {
  margin-top: var(--space-lg);
}

.markdown-body h2 {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-top: var(--space-xl);
  margin-bottom: var(--space-sm);
  color: var(--color-text);
  padding-bottom: var(--space-xs);
  border-bottom: 1px solid var(--color-border);
}

.markdown-body h3 {
  font-size: var(--font-size-md);
  font-weight: 600;
  margin-top: var(--space-lg);
  margin-bottom: var(--space-sm);
  color: var(--color-text);
}

.markdown-body h4 {
  font-size: var(--font-size-base);
  font-weight: 600;
  margin-top: var(--space-md);
  margin-bottom: var(--space-xs);
  color: var(--color-text);
}

.markdown-body p {
  font-size: var(--font-size-base);
  color: var(--color-text-secondary);
  line-height: 1.75;
  margin-bottom: var(--space-md);
}

.markdown-body ul,
.markdown-body ol {
  padding-left: var(--space-lg);
  margin-bottom: var(--space-md);
  color: var(--color-text-secondary);
}

.markdown-body li {
  margin-bottom: var(--space-xs);
  line-height: 1.6;
}

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

.markdown-body blockquote p {
  margin-bottom: 0;
}

.markdown-body code {
  background: var(--color-bg);
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
  font-family: 'SF Mono', 'Fira Code', monospace;
  font-size: 0.85em;
  color: var(--color-accent);
}

.markdown-body pre {
  background: var(--color-code-bg);
  color: var(--color-code-text);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-lg);
  margin: var(--space-md) 0;
  overflow-x: auto;
  line-height: 1.5;
}

.markdown-body pre code {
  background: none;
  padding: 0;
  color: inherit;
  font-size: var(--font-size-xs);
}

.markdown-body img {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius);
  margin: var(--space-md) auto;
  box-shadow: var(--shadow);
  display: block;
}

/* Responsive image sizing — full width on mobile, 60% on laptop/desktop */
@media (min-width: 768px) {
  .markdown-body img.img-half {
    max-width: 60%;
  }
}

.markdown-body figure {
  margin: var(--space-md) 0;
  text-align: center;
}

.markdown-body figure img {
  margin: 0 auto;
}

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

.markdown-body table {
  width: 100%;
  border-collapse: collapse;
  margin: var(--space-md) 0;
  font-size: var(--font-size-sm);
}

.markdown-body th,
.markdown-body td {
  padding: var(--space-sm) var(--space-md);
  border: 1px solid var(--color-border);
  text-align: left;
}

.markdown-body th {
  background: var(--color-bg);
  font-weight: 600;
  color: var(--color-text);
}

.markdown-body td {
  color: var(--color-text-secondary);
}

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

.markdown-body a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}

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

.markdown-body strong {
  font-weight: 600;
  color: var(--color-text);
}

/* --- Tag Badge --- */
.tag-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  padding: 0.2rem 0.6rem;
  background: var(--color-accent-light);
  color: var(--color-accent);
  border-radius: var(--radius-pill);
  font-size: var(--font-size-xs);
  font-weight: 500;
  transition: all var(--transition);
  border: none;
  cursor: pointer;
  text-decoration: none;
}

.tag-badge:hover {
  background: var(--color-accent);
  color: var(--color-accent-text);
}

.tag-badge .tag-count {
  background: rgba(0, 0, 0, 0.08);
  padding: 0.1rem 0.35rem;
  border-radius: var(--radius-pill);
  font-size: var(--font-size-xs);
}

.tag-badge:hover .tag-count {
  background: rgba(255, 255, 255, 0.25);
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-lg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  color: var(--color-text);
  font-family: var(--font-family);
  font-size: var(--font-size-sm);
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition);
  outline: none;
}

.btn:hover {
  background: var(--color-surface-hover);
  border-color: var(--color-accent);
}

.btn:focus-visible {
  outline: none;
  box-shadow: 0 0 0 3px var(--color-accent-light);
  border-color: var(--color-accent);
}

.btn-primary {
  background: var(--color-accent);
  color: var(--color-accent-text);
  border-color: var(--color-accent);
}

.btn-primary:hover {
  background: var(--color-accent-hover);
  border-color: var(--color-accent-hover);
}

.btn-danger {
  color: var(--color-danger);
  border-color: var(--color-danger);
}

.btn-danger:hover {
  background: var(--color-danger);
  color: #fff;
}

/* --- Form Elements --- */
.form-group {
  margin-bottom: var(--space-lg);
}

.form-group label {
  display: block;
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: var(--space-xs);
}

.form-group .hint {
  font-size: var(--font-size-xs);
  color: var(--color-muted);
  margin-top: 2px;
  margin-bottom: var(--space-sm);
}

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

.input:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px var(--color-accent-light);
  background: var(--color-surface);
}

textarea.input {
  resize: vertical;
  min-height: 100px;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md);
}

/* --- JSON Output --- */
.json-output {
  background: var(--color-code-bg);
  color: var(--color-code-text);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-lg);
  font-family: 'SF Mono', 'Fira Code', monospace;
  font-size: var(--font-size-xs);
  line-height: 1.6;
  overflow-x: auto;
  white-space: pre;
  margin-top: var(--space-md);
  position: relative;
}

.json-output .copy-overlay {
  position: absolute;
  top: var(--space-sm);
  right: var(--space-sm);
}

/* --- Stats Grid --- */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: var(--space-md);
  margin-bottom: var(--space-xl);
}

.stat-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-lg) var(--space-md);
  text-align: center;
  position: relative;
  overflow: hidden;
  transition: transform var(--transition), box-shadow var(--transition);
}

.stat-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 20px var(--color-glow), var(--shadow);
}

.stat-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
}

.stat-card::before {
  background: linear-gradient(90deg, var(--color-accent), var(--color-accent-hover));
}

.stat-icon {
  margin-bottom: var(--space-xs);
  color: var(--color-muted);
}

.stat-icon svg {
  width: 24px;
  height: 24px;
}

.stat-card .stat-value {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  color: var(--color-accent);
}

.stat-card .stat-label {
  font-size: var(--font-size-xs);
  color: var(--color-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-top: var(--space-xs);
}

/* --- Dashboard Layout --- */
.dashboard-row {
  display: grid;
  grid-template-columns: 1.6fr 1fr;
  gap: var(--space-lg);
  margin-bottom: var(--space-lg);
}

.dashboard-panel {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-lg);
  margin-bottom: var(--space-lg);
  display: flex;
  flex-direction: column;
}

.dashboard-row .dashboard-panel {
  margin-bottom: 0;
}

.panel-title {
  font-size: var(--font-size-md);
  font-weight: 600;
  color: var(--color-accent);
  margin-bottom: var(--space-md);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.panel-title-icon {
  width: 18px;
  height: 18px;
  color: var(--color-muted);
  flex-shrink: 0;
}

/* --- Timeline toggle (Year / Month) --- */
.timeline-toggle {
  display: flex;
  gap: 2px;
  margin-left: auto;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: calc(var(--radius) - 4px);
  padding: 2px;
}

.timeline-toggle-btn {
  padding: 3px 10px;
  font-size: var(--font-size-xs);
  font-weight: 500;
  font-family: inherit;
  color: var(--color-muted);
  background: transparent;
  border: none;
  border-radius: calc(var(--radius) - 6px);
  cursor: pointer;
  transition: background-color var(--transition), color var(--transition);
}

.timeline-toggle-btn:hover {
  color: var(--color-accent);
}

.timeline-toggle-btn--active {
  background: var(--color-surface);
  color: var(--color-accent);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
}

/* --- Top Tags List --- */
.top-tags-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.top-tags-list--scrollable {
  max-height: 420px;
  overflow-y: auto;
  padding-right: var(--space-xs);
  scrollbar-width: thin;
  scrollbar-color: var(--color-border) transparent;
}

.top-tags-list--scrollable::-webkit-scrollbar {
  width: 6px;
}

.top-tags-list--scrollable::-webkit-scrollbar-track {
  background: transparent;
}

.top-tags-list--scrollable::-webkit-scrollbar-thumb {
  background: var(--color-border);
  border-radius: 3px;
}

.top-tag-item {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  border-radius: calc(var(--radius) - 2px);
  text-decoration: none;
  color: inherit;
  transition: background-color var(--transition);
}

.top-tag-item:hover {
  background: var(--color-bg);
}

.top-tag-rank {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--font-size-xs);
  font-weight: 700;
  color: var(--color-muted);
  flex-shrink: 0;
}

.top-tag-info {
  flex: 1;
  min-width: 0;
}

.top-tag-name {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-accent);
  display: block;
  margin-bottom: 4px;
}

.top-tag-bar-track {
  height: 6px;
  background: var(--color-bg);
  border-radius: 3px;
  overflow: hidden;
}

.top-tag-bar-fill {
  height: 100%;
  background: var(--gradient-accent);
  border-radius: 3px;
  transition: width var(--transition-slow);
}

.top-tag-count {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-accent);
  flex-shrink: 0;
}

.top-tag-pct {
  font-weight: 400;
  color: var(--color-muted);
  font-size: var(--font-size-xs);
}

/* --- Tag Pairs --- */
.tag-pairs-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.tag-pair-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-xs) var(--space-sm);
  font-size: var(--font-size-xs);
  border-radius: 4px;
}

.tag-pair-item:nth-child(odd) {
  background: var(--color-bg);
}

.tag-pair-name {
  color: var(--color-text-secondary);
  font-weight: 500;
}

.tag-pair-count {
  color: var(--color-accent);
  font-weight: 600;
  font-size: var(--font-size-xs);
}

/* --- Tags Cloud (weighted) --- */
.tags-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  align-items: center;
}

.tag-cloud-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--color-accent);
  background: var(--color-accent-subtle);
  border: 1px solid var(--color-accent-light);
  border-radius: var(--radius-pill);
  text-decoration: none;
  font-weight: 500;
  transition: all var(--transition);
  cursor: pointer;
}

.tag-cloud-badge:hover {
  background: var(--color-accent-light);
  border-color: var(--color-accent-border);
  transform: translateY(-1px);
}

.tag-cloud-badge--sm {
  padding: 5px 12px;
  font-size: var(--font-size-xs);
}

.tag-cloud-badge--md {
  padding: 6px 14px;
  font-size: var(--font-size-sm);
}

.tag-cloud-badge--lg {
  padding: 8px 16px;
  font-size: var(--font-size-base);
}

.tag-cloud-badge .tag-count {
  background: var(--color-accent-light);
  border-radius: var(--radius-pill);
  padding: 1px 7px;
  font-size: 0.75em;
  font-weight: 600;
}

/* --- Chart Containers --- */
.chart-container {
  position: relative;
}

.chart-container--timeline {
  min-height: 220px;
  flex: 1;
}

.chart-container--bar {
  height: 500px;
}

/* --- Search Results --- */
.search-mode-badge {
  font-size: var(--font-size-xs);
  padding: 0.15rem 0.5rem;
  border-radius: var(--radius-pill);
  font-weight: 500;
}

.search-mode-badge.exact {
  background: rgba(52, 211, 153, 0.15);
  color: #34d399;
}

.search-mode-badge.fuzzy {
  background: rgba(251, 191, 36, 0.15);
  color: #fbbf24;
}

.search-mode-badge.tfidf {
  background: rgba(129, 140, 248, 0.15);
  color: #818cf8;
}

.search-results-info {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-md);
}

/* --- Empty State --- */
.empty-state {
  text-align: center;
  padding: var(--space-2xl) var(--space-xl);
  color: var(--color-muted);
}

.empty-state .empty-icon {
  font-size: 3rem;
  margin-bottom: var(--space-md);
  opacity: 0.5;
}

.empty-state h3 {
  font-size: var(--font-size-lg);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-sm);
}

.empty-state p {
  font-size: var(--font-size-sm);
}

/* --- Toast --- */
.toast {
  position: fixed;
  bottom: var(--space-xl);
  right: var(--space-xl);
  background: var(--color-text);
  color: var(--color-surface);
  padding: var(--space-sm) var(--space-lg);
  border-radius: var(--radius);
  font-size: var(--font-size-sm);
  font-weight: 500;
  box-shadow: var(--shadow-lg);
  animation: slideUp var(--transition-slow);
  z-index: 1000;
}

.toast.success {
  background: var(--color-success);
}

/* --- Mobile Menu Toggle --- */
.menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-sm);
  color: var(--color-text);
}

.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
  z-index: 90;
}

/* --- Animations --- */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(16px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in {
  animation: fadeIn var(--transition-slow);
}

/* --- About Page --- */
.about-page {
  max-width: var(--content-max-width);
  margin: 0 auto;
}

.about-hero {
  text-align: center;
  padding: var(--space-2xl) 0 var(--space-xl);
}

.about-portrait-wrapper {
  width: 180px;
  height: 180px;
  margin: 0 auto var(--space-xl);
  border-radius: 50%;
  padding: 4px;
  background: var(--gradient-accent);
  box-shadow: 0 0 40px var(--color-glow), 0 0 80px var(--color-accent-subtle);
  transition: box-shadow var(--transition-slow);
}

.about-portrait-wrapper:hover {
  box-shadow: 0 0 50px var(--color-glow), 0 0 100px var(--color-accent-light);
}

.about-portrait {
  width: 100%;
  height: 100%;
  border-radius: 50%;
  object-fit: cover;
  display: block;
  border: 3px solid var(--color-bg);
}

.about-name {
  font-family: var(--font-heading);
  font-size: 2.25rem;
  font-weight: 700;
  background: var(--gradient-accent);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: var(--space-xs);
  letter-spacing: -0.02em;
}

.about-tagline {
  font-size: var(--font-size-lg);
  color: var(--color-text-secondary);
  font-weight: 500;
  margin-bottom: var(--space-lg);
}

.about-socials {
  display: flex;
  justify-content: center;
  gap: var(--space-md);
}

.social-link {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  color: var(--color-text-secondary);
  transition: all var(--transition);
}

.social-link:hover {
  background: var(--color-accent-light);
  border-color: var(--color-accent);
  color: var(--color-accent);
  transform: translateY(-2px);
  box-shadow: 0 0 20px var(--color-glow);
}

.social-link svg {
  width: 20px;
  height: 20px;
}

/* About sections */
.about-section {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  margin-bottom: var(--space-lg);
  transition: box-shadow var(--transition);
}

.about-section:hover {
  box-shadow: 0 0 20px var(--color-accent-subtle);
}

.about-section-header {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--color-border);
}

.about-section-header h2 {
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--color-text);
  margin: 0;
}

.about-section-icon {
  width: 22px;
  height: 22px;
  color: var(--color-accent);
  flex-shrink: 0;
}

.about-section p {
  font-size: var(--font-size-base);
  color: var(--color-text-secondary);
  line-height: 1.75;
  margin-bottom: var(--space-sm);
}

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

.about-section p strong {
  color: var(--color-text);
  font-weight: 600;
}

/* Publications list */
.pub-list {
  list-style: none;
  padding: 0;
  counter-reset: pub-counter;
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.pub-item {
}

.pub-item-link {
  display: flex;
  gap: var(--space-md);
  padding: var(--space-md);
  border-radius: var(--radius);
  transition: background var(--transition);
  text-decoration: none;
  color: inherit;
}

.pub-item-link:hover {
  background: var(--color-bg);
}

.pub-year-badge {
  flex-shrink: 0;
  width: 52px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-accent-light);
  color: var(--color-accent);
  border-radius: var(--radius-pill);
  font-size: var(--font-size-xs);
  font-weight: 700;
  margin-top: 2px;
}

.pub-details {
  flex: 1;
  min-width: 0;
}

.pub-title {
  display: inline;
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-text);
  text-decoration: none;
  line-height: 1.5;
  transition: color var(--transition);
}

.pub-item-link:hover .pub-title {
  color: var(--color-accent);
}

.pub-link-icon {
  display: inline;
  vertical-align: middle;
  margin-left: 4px;
  opacity: 0;
  transition: opacity var(--transition);
}

.pub-item-link:hover .pub-link-icon {
  opacity: 1;
}

.pub-authors {
  font-size: var(--font-size-xs);
  color: var(--color-text-secondary);
  margin-top: 4px;
  margin-bottom: 2px;
}

.pub-venue {
  font-size: var(--font-size-xs);
  color: var(--color-muted);
  font-style: italic;
}

/* --- Neural Network Canvas Background --- */
#neural-bg {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  z-index: 0;
  pointer-events: none;
}

/* --- Landing Page --- */
.landing {
  display: flex;
  align-items: flex-start;
  justify-content: center;
  min-height: 100vh;
  padding: 15vh var(--space-xl) var(--space-xl);
  position: relative;
  z-index: 1;
}

.landing-content {
  text-align: center;
  max-width: 680px;
  width: 100%;
}

.landing-quote-block {
  position: relative;
  margin-bottom: var(--space-2xl);
}

.landing-quote-icon {
  width: 64px;
  height: 64px;
  color: var(--color-accent);
  margin-bottom: var(--space-md);
  animation: pulse-glow 3s ease-in-out infinite;
}

@keyframes pulse-glow {

  0%,
  100% {
    opacity: 0.12;
    transform: scale(1);
  }

  50% {
    opacity: 0.25;
    transform: scale(1.05);
  }
}

.landing-quote {
  font-family: var(--font-heading);
  font-size: 2.25rem;
  font-weight: 600;
  font-style: italic;
  line-height: 1.5;
  letter-spacing: -0.01em;
  margin: 0;
  border: none;
  padding: 0;
  background: var(--gradient-accent);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.landing-author {
  display: block;
  margin-top: var(--space-md);
  font-size: var(--font-size-base);
  font-style: normal;
  font-weight: 500;
  color: var(--color-muted);
  letter-spacing: 0.03em;
}

.landing-search-wrapper {
  position: relative;
  max-width: 520px;
  margin: 0 auto var(--space-lg);
}

.landing-search-icon {
  position: absolute;
  left: var(--space-lg);
  top: 50%;
  transform: translateY(-50%);
  width: 22px;
  height: 22px;
  color: var(--color-muted);
  pointer-events: none;
  transition: color var(--transition);
}

.landing-search-input {
  width: 100%;
  padding: var(--space-md) var(--space-xl);
  padding-left: 3.5rem;
  background: rgba(17, 24, 39, 0.7);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-pill);
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  color: var(--color-text);
  transition: all var(--transition);
  outline: none;
  box-shadow: var(--shadow-sm);
}

.landing-search-input:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 4px var(--color-glow), 0 0 20px var(--color-glow);
}

.landing-search-input:focus~.landing-search-icon {
  color: var(--color-accent);
}

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

.landing-explore {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: var(--font-size-base);
  font-weight: 500;
  color: var(--color-text-secondary);
  text-decoration: none;
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius);
  transition: all var(--transition);
}

.landing-explore:hover {
  color: var(--color-accent);
  background: var(--color-accent-light);
}

.landing-explore svg {
  transition: transform var(--transition);
}

.landing-explore:hover svg {
  transform: translateX(4px);
}

/* When on landing page, hide header elements */
.header-hidden .content-header {
  border-bottom: none;
  background: transparent;
}

.header-hidden #content-title,
.header-hidden .search-bar {
  display: none;
}

/* --- Responsive --- */
@media (max-width: 768px) {
  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .sidebar-overlay.open {
    display: block;
  }

  .main-content {
    margin-left: 0;
  }

  .menu-toggle {
    display: block;
  }

  .content-header {
    flex-wrap: wrap;
    padding: var(--space-md) var(--space-md);
  }

  .search-bar {
    max-width: 100%;
    order: 3;
    flex-basis: 100%;
  }

  .content-body {
    padding: var(--space-md);
  }

  .form-row {
    grid-template-columns: 1fr;
  }

  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .dashboard-row {
    grid-template-columns: 1fr;
  }

  .chart-container--bar {
    height: 400px;
  }

  .top-tags-list--scrollable {
    max-height: 300px;
  }

  /* Landing page — mobile adjustments */
  .landing {
    padding: 8vh var(--space-md) var(--space-md);
  }

  .landing-quote {
    font-size: 1.6rem;
    line-height: 1.45;
  }

  .landing-quote-icon {
    width: 40px;
    height: 40px;
  }

  .landing-search-input {
    font-size: var(--font-size-sm);
    padding: var(--space-sm) var(--space-lg);
    padding-left: 3rem;
  }

  .landing-search-icon {
    left: var(--space-md);
    width: 18px;
    height: 18px;
  }

  /* On landing page (mobile) — keep menu toggle visible, hide other header content */
  .header-hidden .content-header {
    background: transparent;
    border-bottom: none;
  }

  /* Touch-friendly sidebar nav links */
  .sidebar-nav a {
    padding: var(--space-md) var(--space-md);
    font-size: var(--font-size-base);
  }

  /* Prevent horizontal overflow on mobile */
  .main-content {
    overflow-x: hidden;
  }

  /* Markdown tables — horizontal scroll on overflow */
  .markdown-body table {
    display: block;
    overflow-x: auto;
  }

  /* KaTeX display math — scroll instead of overflow */
  .markdown-body .katex-display {
    overflow-x: auto;
    overflow-y: hidden;
    padding-bottom: var(--space-xs);
  }

  /* Paper detail — word wrap and overflow protection */
  .paper-detail {
    overflow-wrap: break-word;
    word-break: break-word;
  }

  /* Paper detail title — smaller on mobile */
  .paper-detail h1 {
    font-size: var(--font-size-md);
    line-height: 1.4;
  }

  /* Markdown headings — smaller on mobile */
  .markdown-body h2 {
    font-size: var(--font-size-md);
  }

  .markdown-body h3 {
    font-size: var(--font-size-base);
  }

  /* Images — always respect viewport width, even with inline width style */
  .markdown-body img {
    max-width: 100% !important;
    height: auto !important;
    width: auto;
  }

  /* About page — mobile adjustments */
  .about-hero {
    padding: var(--space-xl) 0 var(--space-lg);
  }

  .about-portrait-wrapper {
    width: 140px;
    height: 140px;
  }

  .about-name {
    font-size: 1.75rem;
  }

  .about-section {
    padding: var(--space-lg);
  }

  .pub-item-link {
    flex-direction: column;
    gap: var(--space-sm);
  }
}

/* --- Very small screens --- */
@media (max-width: 480px) {
  .landing-quote {
    font-size: 1.35rem;
  }

  .landing-content {
    padding: 0 var(--space-xs);
  }

  .stats-grid {
    grid-template-columns: 1fr;
  }

  .stat-card .stat-value {
    font-size: var(--font-size-xl);
  }

  .content-header h2 {
    font-size: var(--font-size-base);
  }

  /* Paper detail — further reduce on small screens */
  .paper-detail h1 {
    font-size: var(--font-size-base);
  }

  .markdown-body h2 {
    font-size: var(--font-size-base);
  }

  .markdown-body h3 {
    font-size: var(--font-size-sm);
    font-weight: 600;
  }

  .markdown-body p,
  .markdown-body li {
    font-size: var(--font-size-sm);
  }

  .about-name {
    font-size: 1.5rem;
  }

  .about-portrait-wrapper {
    width: 120px;
    height: 120px;
  }
}

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

.graph-page {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  /* Stretch to fill the visible viewport below the sticky header */
  min-height: calc(100vh - 250px);
}

/* Controls panel — reuse dashboard-panel but remove its default margin */
.graph-controls-panel {
  margin-bottom: 0;
  flex-shrink: 0;
}

.graph-controls-top {
  display: flex;
  align-items: flex-end;
  gap: var(--space-xl);
  flex-wrap: wrap;
}

/* --- Slider group --- */
.graph-slider-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.graph-control-label {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

.graph-control-label strong {
  color: var(--color-accent);
}

.graph-slider-track {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.graph-slider-end {
  font-size: var(--font-size-xs);
  color: var(--color-muted);
  min-width: 22px;
}

.graph-slider {
  -webkit-appearance: none;
  appearance: none;
  width: 200px;
  height: 6px;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 3px;
  outline: none;
  cursor: pointer;
}

.graph-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--color-accent);
  border: 2px solid var(--color-bg);
  box-shadow: 0 0 8px var(--color-glow);
  cursor: pointer;
}

.graph-slider::-moz-range-thumb {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--color-accent);
  border: 2px solid var(--color-bg);
  cursor: pointer;
}

/* --- Year legend --- */
.graph-year-legend {
  display: flex;
  gap: var(--space-md);
  align-items: center;
  margin-left: auto;
}

.graph-legend-item {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: var(--font-size-xs);
  color: var(--color-text-secondary);
}

.graph-legend-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  flex-shrink: 0;
  box-shadow: 0 0 6px currentColor;
}

/* --- Filtered tags row --- */
.graph-filtered-tags {
  margin-top: var(--space-sm);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-xs);
  min-height: 26px;
}

.graph-filter-label {
  font-size: var(--font-size-xs);
  color: var(--color-muted);
}

.graph-filtered-badge {
  opacity: 0.55;
  cursor: default !important;
  pointer-events: none;
}

.graph-no-filter {
  font-size: var(--font-size-xs);
  color: var(--color-muted);
  font-style: italic;
}

/* --- SVG canvas wrapper --- */
.graph-canvas-wrapper {
  flex: 1;
  height: calc(100vh - 300px);
  min-height: 420px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  position: relative;
  overflow: hidden;
}

/* --- Tooltip --- */
.graph-tooltip {
  position: fixed;
  background: rgba(11, 17, 32, 0.97);
  border: 1px solid var(--color-accent-border);
  border-radius: var(--radius);
  padding: var(--space-sm) var(--space-md);
  color: var(--color-text);
  font-size: var(--font-size-xs);
  pointer-events: none;
  z-index: 300;
  max-width: 280px;
  display: none;
  line-height: 1.5;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.5), 0 0 0 1px rgba(99, 102, 241, 0.1);
}

.graph-tt-title {
  font-weight: 600;
  color: var(--color-text);
  font-size: var(--font-size-xs);
  line-height: 1.4;
  margin-bottom: 4px;
}

.graph-tt-meta {
  font-size: 11px;
  color: var(--color-muted);
  margin-bottom: 6px;
}

.graph-tt-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 3px;
}

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

/* --- Hint text --- */
.graph-hint {
  position: absolute;
  bottom: var(--space-sm);
  right: var(--space-md);
  font-size: 11px;
  color: var(--color-muted);
  pointer-events: none;
  opacity: 0.55;
  font-family: var(--font-family);
}

/* --- Responsive --- */
@media (max-width: 768px) {
  .graph-canvas-wrapper {
    height: 55vh;
    min-height: 320px;
  }

  .graph-slider {
    width: 140px;
  }

  .graph-controls-top {
    gap: var(--space-md);
  }

  .graph-year-legend {
    margin-left: 0;
  }
}