/* ============================================================
   Formal Conjectures — Main Stylesheet
   ============================================================
   Uses CSS custom properties throughout so theming is easy.
   Class names follow BEM-ish conventions; nothing is deeply
   nested so migrating to React / CSS Modules later is simple.
   ============================================================ */
/* ---- Self-hosted Libertinus fonts (OFL license) ---- */
@font-face {
  font-family: 'Libertinus Sans';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url('../fonts/LibertinusSans-Regular.woff2') format('woff2');
}

@font-face {
  font-family: 'Libertinus Sans';
  font-style: italic;
  font-weight: 400;
  font-display: swap;
  src: url('../fonts/LibertinusSans-Italic.woff2') format('woff2');
}

@font-face {
  font-family: 'Libertinus Sans';
  font-style: normal;
  font-weight: 700;
  font-display: swap;
  src: url('../fonts/LibertinusSans-Bold.woff2') format('woff2');
}

@font-face {
  font-family: 'Libertinus Mono';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url('../fonts/LibertinusMono-Regular.woff2') format('woff2');
}

/* ---- Custom properties ---- */
:root {
  --color-bg:          #ffffff;
  --color-bg-alt:      #f8f9fc;
  --color-border:      #e2e8f0;
  --color-text:        #1a202c;
  --color-text-muted:  #64748b;
  --color-link:        #2563eb;
  --color-link-hover:  #1d4ed8;

  /* Site chrome */
  --color-nav-bg:      #0f172a;
  --color-nav-text:    #e2e8f0;
  --color-nav-hover:   #ffffff;
  --color-footer-bg:   #0f172a;
  --color-footer-text: #94a3b8;

  /* Category badge colours */
  --cat-open:       #f59e0b;  /* amber */
  --cat-open-bg:    #fffbeb;
  --cat-solved:     #10b981;  /* emerald */
  --cat-solved-bg:  #ecfdf5;
  --cat-formal: #047857;
    /* darker green */
    --cat-formal-bg: #ecfdf5;
  --cat-grad:       #3b82f6;  /* blue */
  --cat-grad-bg:    #eff6ff;
  --cat-other:      #6b7280;  /* gray */
  --cat-other-bg:   #f9fafb;

  /* Difficulty */
  --color-difficulty:  #d97706;

  /* Layout */
  --max-width: 1100px;
  --nav-height: 56px;
  --radius: 6px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,.08), 0 1px 2px rgba(0,0,0,.04);
  --shadow-md: 0 4px 6px rgba(0,0,0,.07), 0 2px 4px rgba(0,0,0,.04);

  /* Typography — Libertinus Sans throughout (Biolinum lineage) */
    --font-body: 'Libertinus Sans', 'Segoe UI', system-ui, sans-serif;
    --font-display: 'Libertinus Sans', 'Segoe UI', system-ui, sans-serif;
  --font-mono: 'Libertinus Mono', 'SFMono-Regular', 'Menlo', 'Consolas', monospace;
    --font-serif: 'Libertinus Sans', 'Segoe UI', system-ui, sans-serif;
}

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

html {
  font-size: 17px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a { color: var(--color-link); text-decoration: none; }
a:hover { color: var(--color-link-hover); text-decoration: underline; }

img { max-width: 100%; }
ul, ol { list-style: none; }

/* ---- Utility ---- */
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 1.5rem; }
.visually-hidden { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0,0,0,0); }

/* ============================================================
   Navigation
   ============================================================ */
/* ---- WIP Banner ---- */
.wip-banner {
  background: #fef3c7;
  color: #92400e;
  text-align: center;
  padding: 0.5rem 1rem;
  font-size: 0.85rem;
}

.wip-banner a {
  color: #b45309;
  text-decoration: underline;
}

.wip-banner a:hover {
  color: #92400e;
}
.site-nav {
  background: var(--color-nav-bg);
  height: var(--nav-height);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 1px 0 rgba(255,255,255,.08);
}

.site-nav__inner {
  height: 100%;
  display: flex;
  align-items: center;
  gap: 2rem;
}

.site-nav__brand {
  color: var(--color-nav-text);
  font-family: var(--font-display);
  font-size: 1.1rem;
  letter-spacing: -0.01em;
  flex-shrink: 0;
}
.site-nav__brand:hover { color: var(--color-nav-hover); text-decoration: none; }

.site-nav__logo {
  height: 28px;
  width: auto;
  margin-right: 0.75rem;
  margin-bottom: 2px;
    vertical-align: text-bottom;
  filter: brightness(0) invert(1);
}
.site-nav__links {
  display: flex;
  gap: 0.25rem;
  margin-left: auto;
}

.site-nav__links a {
  color: var(--color-nav-text);
  padding: 0.4rem 0.75rem;
  border-radius: var(--radius);
  font-size: 0.9rem;
  opacity: 0.8;
  transition: opacity 0.15s, background 0.15s;
}
.site-nav__links a:hover {
  opacity: 1;
  background: rgba(255,255,255,.08);
  text-decoration: none;
}
.site-nav__links a.active {
  opacity: 1;
  background: rgba(255,255,255,.12);
}

/* External link icon */
.site-nav__links a[target="_blank"]::after {
  content: ' ↗';
  font-size: 0.75em;
  opacity: 0.6;
}

/* ============================================================
   Footer
   ============================================================ */
.site-footer {
  background: var(--color-footer-bg);
  color: var(--color-footer-text);
  padding: 2rem 0;
  margin-top: auto;
  font-size: 0.875rem;
}

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

.site-footer a { color: #93c5fd; }
.site-footer a:hover { color: #bfdbfe; }

/* ============================================================
   Main content wrapper
   ============================================================ */
main { flex: 1; }

/* ============================================================
   Hero (landing page)
   ============================================================ */
.hero {
  background: linear-gradient(135deg, #0f172a 0%, #1e3a5f 100%);
  color: white;
  padding: 5rem 0 4rem;
  text-align: center;
}

.hero__logo {
  display: block;
  height: 80px;
  width: auto;
  margin: 0 auto 1.5rem;
  filter: brightness(0) invert(1);
}
.hero__title {
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 3.25rem);
  font-weight: normal;
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
}

.hero__subtitle {
  font-size: clamp(1rem, 2.5vw, 1.2rem);
  opacity: 0.8;
  max-width: 600px;
  margin: 0 auto 2rem;
  line-height: 1.7;
}

.hero__actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* ============================================================
   Buttons
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.6rem 1.4rem;
  border-radius: var(--radius);
  font-size: 0.95rem;
  font-weight: 500;
  cursor: pointer;
  border: none;
  transition: all 0.15s;
  text-decoration: none;
}

.btn-primary {
  background: #2563eb;
  color: white;
}
.btn-primary:hover { background: #1d4ed8; color: white; text-decoration: none; }

.btn-secondary {
  background: rgba(255,255,255,.12);
  color: white;
  border: 1px solid rgba(255,255,255,.3);
}
.btn-secondary:hover { background: rgba(255,255,255,.2); color: white; text-decoration: none; }

.btn-outline {
  background: transparent;
  color: var(--color-link);
  border: 1px solid var(--color-border);
}
.btn-outline:hover { background: var(--color-bg-alt); text-decoration: none; }

/* ============================================================
   Stats bar
   ============================================================ */
.stats-bar {
  background: var(--color-bg-alt);
  border-bottom: 1px solid var(--color-border);
  padding: 2rem 0;
}

.stats-bar__grid {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: center;
}

.stat-card {
  background: white;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.25rem 2rem;
  text-align: center;
  box-shadow: var(--shadow-sm);
  min-width: 140px;
  transition: box-shadow 0.15s, transform 0.15s;
}
a.stat-card { color: inherit; text-decoration: none; cursor: pointer; }
a.stat-card:hover { box-shadow: var(--shadow-md); transform: translateY(-2px); text-decoration: none; }

.stat-value {
  display: block;
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-text);
  line-height: 1;
}

.stat-label {
  display: block;
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-top: 0.35rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* ============================================================
   Section layout
   ============================================================ */
.section {
  padding-top: 3rem;
  padding-bottom: 3rem;
}
.section + .section {
  border-top: 1px solid var(--color-border);
}

.section__title {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: normal;
  margin-bottom: 1.5rem;
  color: var(--color-text);
}

/* ============================================================
   Category stats (landing)
   ============================================================ */
.cat-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.cat-stat {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
a.cat-stat { color: inherit; text-decoration: none; }
a.cat-stat:hover { text-decoration: none; opacity: 0.8; }

.cat-count {
  font-weight: 600;
  color: var(--color-text);
}

/* ============================================================
   Collection / subject lists (landing)
   ============================================================ */
.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 3rem; }
@media (max-width: 700px) { .two-col { grid-template-columns: 1fr; } }

.list-links { display: flex; flex-direction: column; gap: 0.5rem; }
.list-links li { display: flex; justify-content: space-between; align-items: center; }
.list-links a { color: var(--color-link); }

.count-badge {
  font-size: 0.8rem;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: 999px;
  padding: 0.1rem 0.55rem;
  color: var(--color-text-muted);
  font-variant-numeric: tabular-nums;
}

/* ============================================================
   Category badges
   ============================================================ */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 0.2rem 0.65rem;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.03em;
}

.cat-open       { background: var(--cat-open-bg);   color: #92400e; border: 1px solid #fde68a; }
.cat-solved     { background: var(--cat-solved-bg); color: #064e3b; border: 1px solid #a7f3d0; }
.cat-formal {
  background: var(--cat-formal-bg);
  color: #064e3b;
  border: 1px solid #6ee7b7;
}
.cat-graduate   { background: var(--cat-grad-bg);   color: #1e40af; border: 1px solid #bfdbfe; }
.cat-undergrad  { background: #eff6ff;              color: #1d4ed8; border: 1px solid #bfdbfe; }
.cat-highschool { background: #ecfeff;              color: #164e63; border: 1px solid #a5f3fc; }
.cat-test       { background: var(--cat-other-bg);  color: #374151; border: 1px solid #e5e7eb; }
.cat-api        { background: var(--cat-other-bg);  color: #374151; border: 1px solid #e5e7eb; }
.cat-unknown    { background: var(--cat-other-bg);  color: #374151; border: 1px solid #e5e7eb; }

/* ============================================================
   Subject pill
   ============================================================ */
.subject-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius);
  font-size: 0.78rem;
  background: #f1f5f9;
  color: #334155;
  border: 1px solid #cbd5e1;
}

/* ============================================================
   Browse page
   ============================================================ */
.browse-layout {
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: 2rem;
  align-items: start;
  padding: 2rem 0;
}
@media (max-width: 800px) {
  .browse-layout { grid-template-columns: 1fr; }
}

/* Sidebar filters */
.filter-panel {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.25rem;
  position: sticky;
  top: calc(var(--nav-height) + 1rem);
}

.filter-panel__title {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  margin-bottom: 0.75rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--color-border);
}

.filter-section { margin-bottom: 1.25rem; }
.filter-section__label { font-size: 0.85rem; font-weight: 600; margin-bottom: 0.5rem; display: block; }

.filter-checkbox-list { display: flex; flex-direction: column; gap: 0.35rem; }
.filter-checkbox-list label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
  cursor: pointer;
  user-select: none;
}
.filter-checkbox-list input[type=checkbox] { accent-color: var(--color-link); }

.filter-reset {
  width: 100%;
  margin-top: 1rem;
  font-size: 0.85rem;
  padding: 0.45rem;
  background: transparent;
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  cursor: pointer;
}
.filter-reset:hover { background: var(--color-bg); }

/* Search bar */
.search-bar {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.search-input {
  flex: 1;
  padding: 0.55rem 0.85rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-size: 0.95rem;
  font-family: inherit;
  background: white;
  color: var(--color-text);
  transition: border-color 0.15s;
}
.search-input:focus {
  outline: none;
  border-color: var(--color-link);
  box-shadow: 0 0 0 3px rgba(37,99,235,.1);
}

/* Results area */
.results-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

.sort-select {
  padding: 0.3rem 0.6rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-size: 0.875rem;
  font-family: inherit;
  background: white;
  cursor: pointer;
}

/* Theorem list */
.theorem-list { display: flex; flex-direction: column; gap: 0.75rem; }

.theorem-card {
  background: white;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.15s, border-color 0.15s;
}
.theorem-card:hover {
  box-shadow: var(--shadow-md);
  border-color: #cbd5e1;
}

.theorem-card__body { flex: 1; min-width: 0; }

.theorem-card__name {
  font-weight: 600;
  font-size: 0.95rem;
  margin-bottom: 0.25rem;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.theorem-card__name a { color: var(--color-text); }
.theorem-card__name a:hover { color: var(--color-link); text-decoration: none; }

.theorem-card__meta {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-bottom: 0.5rem;
}

.theorem-card__tags { display: flex; flex-wrap: wrap; gap: 0.35rem; }

.theorem-card__badge { flex-shrink: 0; }

/* Pagination */
.pagination {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 0.5rem;
  margin-top: 2rem;
  flex-wrap: wrap;
}

.page-btn {
  padding: 0.4rem 0.75rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: white;
  cursor: pointer;
  font-size: 0.875rem;
  transition: all 0.15s;
}
.page-btn:hover { border-color: var(--color-link); color: var(--color-link); }
.page-btn.active { background: var(--color-link); color: white; border-color: var(--color-link); }
.page-btn:disabled { opacity: 0.4; cursor: not-allowed; }

/* ============================================================
   Theorem detail page
   ============================================================ */
.theorem-detail { padding: 2.5rem 0; }

.theorem-detail__breadcrumb {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-bottom: 1.5rem;
}
.theorem-detail__breadcrumb a { color: var(--color-link); }

.theorem-detail__header {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-start;
  gap: 1rem;
  margin-bottom: 2rem;
}

.theorem-detail__title {
  font-family: var(--font-display);
  font-size: clamp(1.4rem, 3vw, 2rem);
  font-weight: normal;
  flex: 1;
}

.theorem-detail__section { margin-bottom: 1.75rem; }

.detail-label {
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  margin-bottom: 0.4rem;
}

.detail-value {
  font-size: 0.95rem;
}

.detail-mono {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 0.75rem 1rem;
  overflow-x: auto;
  white-space: pre-wrap;
  word-break: break-all;
}

.theorem-detail__nav {
  display: flex;
  gap: 1rem;
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--color-border);
}

/* Module siblings list */
.siblings-list { display: flex; flex-direction: column; gap: 0.5rem; margin-top: 0.5rem; }
.sibling-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 0.875rem;
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  background: var(--color-bg-alt);
}
.sibling-item.current { border-color: var(--color-link); background: #eff6ff; }
.sibling-item a { color: var(--color-text); font-weight: 500; }
.sibling-item a:hover { color: var(--color-link); text-decoration: none; }

/* ============================================================
   Info pages (contribute, about)
   ============================================================ */
.page-header {
  background: var(--color-bg-alt);
  border-bottom: 1px solid var(--color-border);
  padding: 3rem 0 2rem;
}

.page-header__title {
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: normal;
}

.page-header__subtitle {
  color: var(--color-text-muted);
  margin-top: 0.5rem;
}

.prose {
  max-width: 720px;
  line-height: 1.8;
}

.prose h2 {
  font-family: var(--font-serif);
  font-size: 1.4rem;
  font-weight: normal;
  margin: 2rem 0 0.75rem;
}

.prose h3 {
  font-size: 1.05rem;
  margin: 1.5rem 0 0.5rem;
}

.prose p { margin-bottom: 1rem; }

.prose ul, .prose ol {
  list-style: disc;
  padding-left: 1.75rem;
  margin-bottom: 1rem;
}
.prose ol { list-style: decimal; }
.prose li { margin-bottom: 0.35rem; }

.prose code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: 3px;
  padding: 0.1em 0.35em;
}

.prose pre {
  background: #0f172a;
  color: #e2e8f0;
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin-bottom: 1.25rem;
}
.prose pre code {
  background: none;
  border: none;
  padding: 0;
  font-size: 0.875rem;
  color: inherit;
}

.prose a { color: var(--color-link); }
.prose blockquote {
  border-left: 3px solid var(--color-border);
  padding-left: 1rem;
  color: var(--color-text-muted);
  margin: 1rem 0;
}

/* ============================================================
   Empty / loading states
   ============================================================ */
.empty-state {
  text-align: center;
  padding: 4rem 2rem;
  color: var(--color-text-muted);
}
.empty-state__icon { font-size: 3rem; margin-bottom: 1rem; }
.empty-state__text { font-size: 1rem; }

.loading-spinner {
  display: inline-block;
  width: 1.5rem;
  height: 1.5rem;
  border: 2px solid var(--color-border);
  border-top-color: var(--color-link);
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ============================================================
   Voting system
   ============================================================ */
.vote-widget {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 2rem;
}

.vote-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.45rem 1rem;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  background: white;
  color: var(--color-text-muted);
  font-size: 0.875rem;
  font-family: inherit;
  cursor: pointer;
  transition: all 0.15s;
}
.vote-btn:hover {
  border-color: var(--color-link);
  color: var(--color-link);
}
.vote-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.vote-btn--active {
  background: #eff6ff;
  border-color: var(--color-link);
  color: var(--color-link);
}

.vote-count {
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}

.theorem-card__votes {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  font-size: 0.78rem;
  color: var(--color-link);
  margin-right: 0.5rem;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}

.auth-prompt {
  font-size: 0.8rem;
  color: var(--color-text-muted);
}
.auth-prompt:hover {
  color: var(--color-link);
}

/* Difficulty rating */
.difficulty-widget {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 2rem;
  flex-wrap: wrap;
}

.difficulty-select {
  padding: 0.35rem 0.6rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-size: 0.875rem;
  font-family: inherit;
  background: white;
  cursor: pointer;
}
.difficulty-select:focus {
  outline: none;
  border-color: var(--color-link);
  box-shadow: 0 0 0 3px rgba(37,99,235,.1);
}

.difficulty-display {
  font-size: 0.875rem;
  color: var(--color-text-muted);
}
.difficulty-display strong {
  color: var(--color-text);
}

.difficulty-clear-btn {
  font-size: 0.78rem;
  padding: 0.25rem 0.6rem;
}

.theorem-card__difficulty {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  font-size: 0.78rem;
  color: var(--color-difficulty);
  margin-right: 0.5rem;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}

/* Discussion link */
.discussion-link {
  display: inline-block;
  font-size: 0.85rem;
  color: var(--color-link);
  margin-bottom: 1rem;
}
.discussion-link--loading {
  color: var(--color-text-muted);
}

/* Truth prediction */
.truth-widget {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 2rem;
}

.truth-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.45rem 0.85rem;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  background: white;
  color: var(--color-text-muted);
  font-size: 0.875rem;
  font-family: inherit;
  cursor: pointer;
  transition: all 0.15s;
}
.truth-btn:hover {
  border-color: var(--color-text-muted);
  color: var(--color-text);
}
.truth-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.truth-btn__label { font-weight: 600; }
.truth-btn__count { font-weight: 600; font-variant-numeric: tabular-nums; }

.truth-btn--active-up {
  background: #ecfdf5;
  border-color: #10b981;
  color: #065f46;
}
.truth-btn--active-up:hover {
  border-color: #059669;
  color: #064e3b;
}

.truth-btn--active-down {
  background: #fef2f2;
  border-color: #ef4444;
  color: #991b1b;
}
.truth-btn--active-down:hover {
  border-color: #dc2626;
  color: #7f1d1d;
}

.theorem-card__truth {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  font-size: 0.78rem;
  color: var(--color-text-muted);
  margin-right: 0.5rem;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}

/* ============================================================
   Consent modal
   ============================================================ */
.consent-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
}

.consent-dialog {
  background: white;
  border-radius: var(--radius);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
  max-width: 520px;
  width: 100%;
  padding: 2rem;
  max-height: 90vh;
  overflow-y: auto;
}

.consent-dialog__title {
  font-family: var(--font-display);
  font-size: 1.3rem;
  font-weight: normal;
  margin-bottom: 1rem;
}

.consent-dialog__body {
  font-size: 0.9rem;
  line-height: 1.7;
  color: var(--color-text);
  margin-bottom: 1.5rem;
}

.consent-dialog__body p {
  margin-bottom: 0.75rem;
}

.consent-dialog__body ul {
  list-style: disc;
  padding-left: 1.5rem;
  margin-bottom: 0.75rem;
}

.consent-dialog__body li {
  margin-bottom: 0.25rem;
}

.consent-dialog__body a {
  color: var(--color-link);
}

.consent-dialog__actions {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}

/* ============================================================
   Hamburger menu button (hidden on desktop)
   ============================================================ */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--color-nav-text);
  font-size: 1.5rem;
  cursor: pointer;
  padding: 0.25rem;
  line-height: 1;
  margin-left: auto;
}

/* ============================================================
   Filter toggle button (hidden on desktop)
   ============================================================ */
.filter-toggle {
  display: none;
  width: 100%;
  padding: 0.6rem 1rem;
  margin-bottom: 1rem;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-size: 0.9rem;
  font-family: inherit;
  font-weight: 600;
  color: var(--color-text);
  cursor: pointer;
}

/* ============================================================
   Responsive tweaks
   ============================================================ */

/* --- Tablet and below: collapsible filters --- */
@media (max-width: 800px) {
  .filter-toggle { display: block; }

  .filter-panel {
    position: static;
    display: none;
  }
  .filter-panel.is-open { display: block; }
}

/* --- Phone --- */
@media (max-width: 600px) {
  .container { padding: 0 2rem; }
  .page-header .container { padding: 0 2rem; }
  .hero { padding: 3rem 0 2.5rem; }
  .stats-bar__grid { flex-direction: column; align-items: center; }
  .theorem-detail__header { flex-direction: column; }

  /* Hamburger nav */
  .nav-toggle { display: block; }

  .site-nav { height: auto; min-height: var(--nav-height); }
  .site-nav__inner { flex-wrap: wrap; }

  .site-nav__links {
    display: none;
    flex-basis: 100%;
    flex-direction: column;
    gap: 0;
    padding-bottom: 0.5rem;
  }
  .site-nav__links.is-open { display: flex; }

  .site-nav__links a {
    padding: 0.6rem 0.75rem;
    font-size: 0.95rem;
    opacity: 1;
  }

  /* Theorem card: stack body and badge vertically */
  .theorem-card {
    flex-direction: column;
    gap: 0.5rem;
  }

  .theorem-card__badge {
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem;
  }

  /* Theorem card: allow name wrapping */
  .theorem-card__name {
    white-space: normal;
    word-break: break-word;
  }

  /* Stack search bar and results meta */
  .results-meta {
    flex-direction: column;
    align-items: stretch;
    gap: 0.5rem;
  }

  /* Larger tap targets for buttons */
  .vote-btn, .truth-btn {
    padding: 0.55rem 1.1rem;
    font-size: 0.95rem;
  }

  .filter-checkbox-list label {
    padding: 0.3rem 0;
    font-size: 0.95rem;
  }

  .page-btn {
    padding: 0.5rem 0.85rem;
  }
}

/* ---- Verso literate integration ---- */
.verso-doc-content {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: 0.5rem;
  padding: 1rem 1.25rem;
  margin-top: 0.5rem;
  line-height: 1.6;
  font-size: 0.95rem;
}

.verso-doc-content h2 {
  font-size: 1.15rem;
  margin: 0 0 0.5rem;
}

.verso-doc-content p {
  margin: 0.4rem 0;
}

.verso-doc-content a {
  color: var(--color-link);
  text-decoration: underline;
}

.verso-code-container {
  margin-top: 0.5rem;
  border: 1px solid var(--color-border);
  border-radius: 0.5rem;
  overflow-x: auto;
  background: var(--color-bg-alt);
}

.verso-code-container code.hl {
  display: block;
  padding: 1rem 1.25rem;
  font-size: 0.875rem;
  line-height: 1.6;
}

.verso-code-loading {
  padding: 1.5rem;
  text-align: center;
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

.verso-code-fallback {
  padding: 1rem 1.25rem;
  font-size: 0.9rem;
}

@media (max-width: 768px) {
  .verso-code-container code.hl {
    font-size: 0.8rem;
    padding: 0.75rem 1rem;
  }
}