:root {
  --pb-primary: #3AB6C6;
  --pb-primary-dark: #2C95A5;
  --pb-green: #B6E3D4;
  --pb-green-dark: #8FCFBE;
  --pb-secondary: #B6E3D4;
  --pb-tertiary: #87D7DE;
  --pb-dark: #002A3D;
  --pb-dark-deeper: #001C29;
  --pb-dark-mid: #0C4B5C;
  --pb-warm: #E7F6F1;
  --pb-grey-100: #F2FAF8;
  --pb-grey-200: #DCECE7;
  --pb-grey-250: #A7BEC0;
  --pb-grey-300: #CCCCCC;
  --pb-white: #ffffff;
  --pb-black: #000000;
  --color-card-bg: rgba(0, 42, 61, 0.6);
  --color-card-border: rgba(58, 182, 198, 0.18);
  --color-glass-bg: rgba(255, 255, 255, 0.04);
  --color-glass-border: rgba(255, 255, 255, 0.08);
  --shadow-soft: 0 4px 24px rgba(0, 0, 0, 0.2);
  --shadow-glow: 0 0 30px rgba(58, 182, 198, 0.15);
  --shadow-card: 0 8px 32px rgba(0, 0, 0, 0.3);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --font-main: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --max-width: 800px;
  --max-width-wide: 1200px;
  --transition-base: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; }
body { font-family: var(--font-main); background: var(--pb-dark-deeper); color: var(--pb-grey-200); line-height: 1.7; overflow-x: hidden; }
a { color: var(--pb-primary); text-decoration: none; transition: color var(--transition-base); }
a:hover { color: var(--pb-tertiary); }
a:focus-visible { outline: 2px solid var(--pb-primary); outline-offset: 2px; border-radius: 2px; }
h1, h2, h3, h4, h5, h6 { line-height: 1.2; font-weight: 700; color: var(--pb-white); }

/* ─── Nav ─── */
.nav {
  position: sticky; top: 0; left: 0; right: 0; z-index: 1100;
  padding: 12px 0;
  background: rgba(0, 26, 40, 0.95);
  backdrop-filter: blur(20px); -webkit-backdrop-filter: blur(20px);
  box-shadow: 0 2px 20px rgba(0, 0, 0, 0.3);
  border-bottom: 1px solid var(--color-glass-border);
}
.nav-inner { display: flex; align-items: center; justify-content: space-between; max-width: var(--max-width-wide); margin: 0 auto; padding: 0 24px; }
.nav-brand { display: flex; align-items: center; position: relative; z-index: 1100; }
.nav-brand img { height: 32px; width: auto; }
.nav-links { display: flex; gap: 24px; list-style: none; flex-wrap: wrap; }
.nav-links a { color: var(--pb-grey-250); font-size: 0.82rem; font-weight: 500; transition: color var(--transition-base); }
.nav-links a:hover { color: var(--pb-white); }

/* ─── Hamburger toggle ─── */
.nav-toggle {
  display: none;
  background: none; border: none; cursor: pointer;
  width: 44px; height: 44px;
  position: relative; z-index: 1100;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}
.nav-toggle-bar {
  display: block;
  width: 24px; height: 2px;
  background: var(--pb-white);
  border-radius: 2px;
  position: absolute; left: 10px;
  transition: transform 0.4s cubic-bezier(0.23, 1, 0.32, 1),
              opacity 0.3s ease,
              background 0.3s ease;
}
.nav-toggle-bar:nth-child(1) { top: 14px; }
.nav-toggle-bar:nth-child(2) { top: 21px; }
.nav-toggle-bar:nth-child(3) { top: 28px; }

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(1) {
  top: 21px;
  transform: rotate(45deg);
  background: var(--pb-primary);
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(3) {
  top: 21px;
  transform: rotate(-45deg);
  background: var(--pb-primary);
}

/* ─── Mobile menu overlay ─── */
.nav-overlay {
  display: none;
  position: fixed; inset: 0;
  z-index: 1050;
  background: rgba(0, 18, 28, 0.97);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  flex-direction: column;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.nav-overlay.open {
  display: flex;
}

.nav-overlay-links {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}
.nav-overlay-links li {
  opacity: 0;
  transform: translateY(16px);
}
.nav-overlay.open .nav-overlay-links li {
  animation: menuLinkIn 0.4s cubic-bezier(0.23, 1, 0.32, 1) forwards;
}
.nav-overlay.open .nav-overlay-links li:nth-child(1) { animation-delay: 0.06s; }
.nav-overlay.open .nav-overlay-links li:nth-child(2) { animation-delay: 0.10s; }
.nav-overlay.open .nav-overlay-links li:nth-child(3) { animation-delay: 0.14s; }
.nav-overlay.open .nav-overlay-links li:nth-child(4) { animation-delay: 0.18s; }
.nav-overlay.open .nav-overlay-links li:nth-child(5) { animation-delay: 0.22s; }
.nav-overlay.open .nav-overlay-links li:nth-child(6) { animation-delay: 0.26s; }
.nav-overlay.open .nav-overlay-links li:nth-child(7) { animation-delay: 0.30s; }
.nav-overlay.open .nav-overlay-links li:nth-child(8) { animation-delay: 0.34s; }

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

.nav-overlay-links a {
  display: block;
  padding: 14px 40px;
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--pb-grey-200);
  text-decoration: none;
  letter-spacing: -0.01em;
  position: relative;
  transition: color 0.25s ease;
  border-radius: var(--radius-sm);
}
.nav-overlay-links a:hover { color: var(--pb-white); }
.nav-overlay-links a:focus-visible {
  color: var(--pb-white);
  outline: 2px solid var(--pb-primary);
  outline-offset: 2px;
}
.nav-overlay-links a[aria-current="page"] {
  color: var(--pb-primary);
}

/* ─── Breadcrumb ─── */
.breadcrumb { max-width: var(--max-width); margin: 0 auto; padding: 20px 24px 0; }
.breadcrumb ol { list-style: none; display: flex; flex-wrap: wrap; gap: 6px; font-size: 0.8rem; }
.breadcrumb li { display: flex; align-items: center; gap: 6px; color: var(--pb-grey-250); }
.breadcrumb li::after { content: '/'; opacity: 0.4; }
.breadcrumb li:last-child::after { content: ''; }
.breadcrumb li:last-child { color: var(--pb-primary); }
.breadcrumb a { color: var(--pb-grey-250); }
.breadcrumb a:hover { color: var(--pb-white); }

/* ─── Page container ─── */
.page { max-width: var(--max-width); margin: 0 auto; padding: 48px 24px 80px; }
.page-wide { max-width: var(--max-width-wide); }

/* ─── Page header ─── */
.page-header { margin-bottom: 48px; }
.page-title { font-size: clamp(1.75rem, 4vw, 2.5rem); font-weight: 800; margin-bottom: 16px; letter-spacing: -0.02em; }
.page-subtitle { font-size: 1.05rem; color: var(--pb-grey-250); line-height: 1.7; max-width: 650px; }
.page-meta { display: flex; flex-wrap: wrap; gap: 16px; margin-top: 16px; font-size: 0.78rem; color: var(--pb-grey-250); }
.page-meta span { display: flex; align-items: center; gap: 5px; }

/* ─── Prose content ─── */
.prose h2 { font-size: 1.4rem; margin: 40px 0 16px; }
.prose h3 { font-size: 1.1rem; margin: 28px 0 12px; color: var(--pb-primary); }
.prose p { margin-bottom: 16px; line-height: 1.8; }
.prose ul, .prose ol { margin: 0 0 20px 20px; }
.prose li { margin-bottom: 8px; line-height: 1.7; }
.prose li strong { color: var(--pb-white); }
.prose blockquote { border-left: 3px solid var(--pb-primary); padding: 16px 20px; margin: 24px 0; background: var(--color-glass-bg); border-radius: 0 var(--radius-sm) var(--radius-sm) 0; font-style: italic; color: var(--pb-grey-200); }
.prose sup a { color: var(--pb-primary); font-weight: 600; text-decoration: none; }
.prose hr { border: none; border-top: 1px solid var(--color-card-border); margin: 40px 0; }

/* ─── Cards ─── */
.card { background: var(--color-glass-bg); border: 1px solid var(--color-card-border); border-radius: var(--radius-lg); padding: 28px; transition: all var(--transition-base); }
.card:hover { border-color: rgba(58, 182, 198, 0.3); box-shadow: var(--shadow-glow); }
.card-grid { display: grid; gap: 20px; }
.card-grid-2 { grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); }
.card-grid-3 { grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }
.card-grid-4 { grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); }

/* ─── Stat card (Key Facts) ─── */
.stat-card { text-align: center; padding: 32px 24px; }
.stat-number { font-size: 2rem; font-weight: 800; color: var(--pb-white); margin-bottom: 8px; }
.stat-number.text-stat { font-size: 1.4rem; }
.stat-label { font-size: 0.9rem; color: var(--pb-grey-250); line-height: 1.5; margin-bottom: 12px; }
.stat-source { font-size: 0.72rem; color: var(--pb-primary); }

/* ─── Fact list ─── */
.fact-list { list-style: none; margin: 0 0 24px; padding: 0; }
.fact-list li { padding: 12px 0; border-bottom: 1px solid var(--color-glass-border); display: flex; gap: 12px; align-items: baseline; }
.fact-list li:last-child { border-bottom: none; }
.fact-list .fact-key { font-weight: 600; color: var(--pb-white); min-width: 160px; flex-shrink: 0; font-size: 0.9rem; }
.fact-list .fact-value { color: var(--pb-grey-200); font-size: 0.9rem; }

/* ─── Definition box ─── */
.def-box { background: rgba(58, 182, 198, 0.07); border: 1px solid rgba(58, 182, 198, 0.15); border-radius: var(--radius-sm); padding: 20px 24px; margin: 20px 0; }
.def-box dt { font-weight: 700; color: var(--pb-primary); font-size: 0.9rem; margin-bottom: 4px; }
.def-box dd { font-size: 0.88rem; color: var(--pb-grey-200); line-height: 1.6; margin-bottom: 16px; }
.def-box dd:last-child { margin-bottom: 0; }

/* ─── Tag / badge ─── */
.badge { display: inline-block; padding: 3px 12px; border-radius: 100px; font-size: 0.7rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.05em; }
.badge-primary { background: rgba(58, 182, 198, 0.15); color: var(--pb-primary); }
.badge-green { background: rgba(182, 227, 212, 0.18); color: var(--pb-secondary); }
.badge-orange { background: rgba(255, 107, 53, 0.15); color: #FF6B35; }

/* ─── Cite box ─── */
.cite-box { background: var(--color-glass-bg); border: 1px solid var(--color-card-border); border-radius: var(--radius-lg); padding: 28px; margin-top: 48px; }
.cite-box h3 { font-size: 1rem; margin-bottom: 12px; }
.cite-box .cite-text { background: rgba(0, 0, 0, 0.3); border: 1px solid var(--color-glass-border); border-radius: var(--radius-sm); padding: 16px; font-size: 0.82rem; color: var(--pb-grey-200); line-height: 1.6; font-style: italic; margin-bottom: 12px; }
.cite-box button { padding: 8px 20px; border-radius: 100px; font-size: 0.78rem; font-weight: 600; font-family: var(--font-main); cursor: pointer; transition: all var(--transition-base); background: var(--color-glass-bg); border: 1px solid var(--color-glass-border); color: var(--pb-grey-250); }
.cite-box button:hover { background: rgba(58, 182, 198, 0.1); border-color: var(--pb-primary); color: var(--pb-white); }

/* ─── Caveat / methodology note ─── */
.caveat { padding: 0; margin: 8px 0 0; }
.caveat h3 { color: var(--pb-grey-250); font-size: 0.75rem; font-weight: 600; text-transform: uppercase; letter-spacing: 0.06em; margin-bottom: 4px; }
.caveat p { font-size: 0.82rem; line-height: 1.65; margin: 0; color: var(--pb-grey-250); }

/* ─── Related links ─── */
.related { margin-top: 48px; }
.related h2 { font-size: 1.2rem; margin-bottom: 16px; }
.related-list { list-style: none; padding: 0; }
.related-list li { padding: 10px 0; border-bottom: 1px solid var(--color-glass-border); }
.related-list li:last-child { border-bottom: none; }
.related-list a { display: flex; justify-content: space-between; align-items: center; color: var(--pb-grey-200); }
.related-list a:hover { color: var(--pb-white); }
.related-list .related-arrow { color: var(--pb-primary); font-size: 0.9rem; transition: transform var(--transition-base); }
.related-list a:hover .related-arrow { transform: translateX(4px); }

/* ─── Source list ─── */
.source-list { list-style: none; padding: 0; counter-reset: src; }
.source-list li { padding: 14px 0; font-size: 0.88rem; line-height: 1.7; padding-left: 32px; position: relative; }
.source-list li + li { border-top: 1px solid var(--color-glass-border); }
.source-list li::before { counter-increment: src; content: counter(src) "."; font-weight: 700; color: var(--pb-primary); position: absolute; left: 0; top: 14px; }
.source-list li em { color: var(--pb-grey-250); }
.source-list li a { word-break: break-word; }

/* ─── FAQ accordion ─── */
.faq-list { display: flex; flex-direction: column; gap: 12px; }
.faq-item { background: var(--color-glass-bg); border: 1px solid var(--color-card-border); border-radius: var(--radius-md); overflow: hidden; }
.faq-q { width: 100%; padding: 18px 24px; background: none; border: none; color: var(--pb-white); font-size: 0.95rem; font-weight: 600; font-family: var(--font-main); text-align: left; cursor: pointer; display: flex; align-items: center; justify-content: space-between; gap: 16px; transition: color var(--transition-base); }
.faq-q:hover { color: var(--pb-primary); }
.faq-q::after { content: '+'; font-size: 1.4rem; font-weight: 300; color: var(--pb-primary); flex-shrink: 0; transition: transform 0.3s ease; }
.faq-item.open .faq-q::after { content: '−'; }
.faq-a { max-height: 0; overflow: hidden; transition: max-height 0.4s cubic-bezier(0.4, 0, 0.2, 1); }
.faq-a-inner { padding: 0 24px 20px; font-size: 0.9rem; color: var(--pb-grey-250); line-height: 1.8; }
.faq-a-inner p { margin-bottom: 10px; }
.faq-a-inner p:last-child { margin-bottom: 0; }

/* ─── Source card (for sources page) ─── */
.source-card { display: flex; flex-direction: column; }
.source-card h3 { font-size: 0.95rem; margin-bottom: 8px; line-height: 1.4; }
.source-card .source-meta { font-size: 0.8rem; color: var(--pb-grey-250); margin-bottom: 12px; line-height: 1.5; }
.source-card .source-link { margin-top: auto; display: inline-flex; align-items: center; gap: 6px; font-size: 0.82rem; font-weight: 600; }

/* ─── Glossary ─── */
.glossary-term { padding: 20px 0; border-bottom: 1px solid var(--color-glass-border); }
.glossary-term:last-child { border-bottom: none; }
.glossary-term h3 { font-size: 1rem; color: var(--pb-white); margin-bottom: 6px; }
.glossary-term p { font-size: 0.9rem; color: var(--pb-grey-250); line-height: 1.7; margin: 0; }
.glossary-term .term-source { font-size: 0.75rem; color: var(--pb-primary); margin-top: 6px; }

/* ─── Copy-link button (glossary headings) ─── */
.copy-link-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: none;
  border: none;
  cursor: pointer;
  color: var(--pb-grey-250);
  opacity: 0;
  padding: 2px;
  margin-left: 6px;
  vertical-align: middle;
  border-radius: 4px;
  transition: opacity var(--transition-base), color var(--transition-base), background var(--transition-base);
  position: relative;
}
.glossary-term:hover .copy-link-btn,
.copy-link-btn:focus-visible { opacity: 1; }
.copy-link-btn:hover { color: var(--pb-primary); background: rgba(58, 182, 198, 0.1); }
.copy-link-btn:focus-visible { outline: 2px solid var(--pb-primary); outline-offset: 2px; opacity: 1; }
.copy-link-btn::after {
  content: 'Copied!';
  position: absolute;
  left: calc(100% + 8px);
  top: 50%;
  transform: translateY(-50%);
  font-size: 0.7rem;
  font-weight: 600;
  font-family: var(--font-main);
  color: var(--pb-primary);
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease;
}
.copy-link-btn.copied { opacity: 1; color: var(--pb-primary); }
.copy-link-btn.copied::after { opacity: 1; }

/* ─── Feature cards (replaces em-dash bullet lists) ─── */
.feature-grid {
  display: grid;
  gap: 12px;
  margin: 16px 0 24px;
  padding: 0;
  list-style: none;
}
.feature-grid-2 { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }

.feature-card {
  display: flex;
  flex-direction: column;
  justify-content: center;
  background: var(--color-glass-bg);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  transition: border-color var(--transition-base), box-shadow var(--transition-base);
}
.feature-card:hover {
  border-color: rgba(58, 182, 198, 0.3);
  box-shadow: 0 0 20px rgba(58, 182, 198, 0.08);
}
.feature-card h3,
.feature-card .feature-title {
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--pb-white);
  margin: 0 0 6px;
  line-height: 1.3;
}
.feature-card p,
.feature-card .feature-desc {
  font-size: 0.86rem;
  color: var(--pb-grey-250);
  line-height: 1.65;
  margin: 0;
}
.feature-card sup a {
  color: var(--pb-primary);
  font-weight: 600;
  text-decoration: none;
}
.feature-card a.feature-link {
  color: var(--pb-primary);
  font-weight: 600;
}
.feature-card a.feature-link:hover {
  color: var(--pb-tertiary);
}

/* ─── Footer ─── */
.footer { padding: 40px 24px; border-top: 1px solid var(--color-glass-border); text-align: center; margin-top: 48px; }
.footer p { font-size: 0.8rem; color: var(--pb-grey-250); }
.footer a { color: var(--pb-primary); }
.footer-links { display: flex; flex-wrap: wrap; justify-content: center; gap: 20px; margin-bottom: 16px; }
.footer-links a { font-size: 0.78rem; color: var(--pb-grey-250); }
.footer-links a:hover { color: var(--pb-white); }

/* ─── Responsive ─── */
@media (max-width: 768px) {
  .nav-links { display: none; }
  .nav-toggle { display: flex; align-items: center; justify-content: center; }
  .page { padding: 32px 20px 60px; }
  .fact-list li { flex-direction: column; gap: 2px; }
  .fact-list .fact-key { min-width: auto; }
  .card-grid-2, .card-grid-3, .card-grid-4 { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
  .page-title { font-size: 1.5rem; }
  .nav-overlay-links a { font-size: 1.1rem; padding: 12px 28px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; scroll-behavior: auto !important; }
}