/* ═══════════════════════════════════════════════════════════════════
   Deep Research Engine — Shared Design System
   Premium editorial aesthetic · customize :root vars per project
   ═══════════════════════════════════════════════════════════════════ */

/* ─── Design Tokens — AI vs Human Sandbox overrides ─────────────── */
:root {
  --c-bg:            #0a0e17;
  --c-bg-alt:        #111827;
  --c-bg-card:       #1a2235;
  --c-bg-lift:       #1e2a40;
  --c-parchment:     #e2e8f0;
  --c-parchment-dim: #94a3b8;
  --c-gold:          #f59e0b;
  --c-gold-dim:      #b45309;
  --c-teal:          #38bdf8;
  --c-teal-dim:      #0369a1;
  --c-amber:         #f59e0b;
  --c-border:        rgba(56,189,248,0.12);
  --c-border-strong: rgba(56,189,248,0.30);

  --f-title:  'Inter', sans-serif;
  --f-body:   'Inter', sans-serif;
  --f-prose:  'Source Serif 4', Georgia, serif;
  --f-ui:     'Inter', sans-serif;

  --radius:    6px;
  --radius-lg: 12px;
  --max-w:     960px;
}

/* ─── Reset ──────────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

body {
  background: var(--c-bg);
  color: var(--c-parchment);
  font-family: var(--f-body);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

/* ─── Typography ─────────────────────────────────────────────────── */
h1, h2, h3, h4 {
  font-family: var(--f-title);
  letter-spacing: 0.02em;
  line-height: 1.2;
}
h1 { font-size: clamp(2.2rem, 5vw, 3.8rem); font-weight: 800; color: var(--c-parchment); }
h2 { font-size: clamp(1.5rem, 2.8vw, 2rem);  font-weight: 700; color: var(--c-teal); }
h3 { font-size: 1.1rem; font-weight: 600; color: var(--c-parchment); }
h4 { font-size: 0.95rem; font-weight: 600; color: var(--c-gold); letter-spacing: 0.06em; }

p {
  font-family: var(--f-prose);
  font-size: 1.1rem;
  color: var(--c-parchment-dim);
}
p + p { margin-top: 1rem; }
strong { color: var(--c-parchment); font-weight: 600; }
em { color: var(--c-parchment); }

a { color: var(--c-teal); text-decoration: none; }
a:hover { color: var(--c-gold); }

/* ─── Layout ─────────────────────────────────────────────────────── */
.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 2rem;
}
section { padding: 5rem 0; }
section + section { border-top: 1px solid var(--c-border); }

/* ─── Navigation ─────────────────────────────────────────────────── */
.site-nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  padding: 1rem 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: rgba(10,14,23,0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--c-border);
}
.nav-logo {
  font-family: var(--f-title);
  font-size: 0.85rem;
  letter-spacing: 0.08em;
  color: var(--c-gold);
  text-transform: uppercase;
  text-decoration: none;
  font-weight: 700;
}
.nav-links { display: flex; gap: 1.75rem; list-style: none; }
.nav-links a {
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--c-parchment-dim);
  text-decoration: none;
  transition: color 0.2s;
}
.nav-links a:hover { color: var(--c-teal); }

.nav-right {
  display: flex;
  align-items: center;
  gap: 2rem;
}

/* ─── Language switcher ──────────────────────────────────────────── */
.lang-switcher {
  display: flex;
  align-items: center;
  gap: 0.15rem;
  border-left: 1px solid var(--c-border);
  padding-left: 1.25rem;
}
.lang-btn {
  font-family: var(--f-ui);
  font-size: 0.62rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--c-parchment-dim);
  text-decoration: none;
  padding: 0.2rem 0.45rem;
  border-radius: 3px;
  transition: color 0.2s, background 0.2s;
}
.lang-btn:hover { color: var(--c-parchment); background: rgba(255,255,255,0.05); }
.lang-btn.lang-active {
  color: var(--c-teal);
  background: rgba(56,189,248,0.08);
}

/* ─── Breadcrumb ──────────────────────────────────────────────────── */
.breadcrumb {
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  color: var(--c-parchment-dim);
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 2rem;
  padding-top: 6rem;
}
.breadcrumb a { color: var(--c-teal-dim); text-decoration: none; }
.breadcrumb a:hover { color: var(--c-teal); }
.breadcrumb-sep { opacity: 0.4; }

/* ─── Page Header (for research pages) ───────────────────────────── */
.page-header {
  padding: 2rem 0 4rem;
  border-bottom: 1px solid var(--c-border);
  margin-bottom: 4rem;
}
.page-header-eyebrow {
  font-size: 0.68rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--c-teal-dim);
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}
.page-header-eyebrow::before {
  content: '';
  display: inline-block;
  width: 1.5rem;
  height: 1px;
  background: var(--c-teal);
}
.page-subtitle {
  font-family: var(--f-prose);
  font-size: 1.3rem;
  font-style: italic;
  color: var(--c-parchment-dim);
  margin-top: 1rem;
  max-width: 65ch;
}

/* ─── Section Header ─────────────────────────────────────────────── */
.section-header { margin-bottom: 2.5rem; }
.section-eyebrow {
  font-size: 0.68rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--c-teal-dim);
  margin-bottom: 0.6rem;
}

/* ─── Cards ──────────────────────────────────────────────────────── */
.card {
  background: var(--c-bg-card);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  transition: border-color 0.25s, transform 0.25s;
}
.card:hover { border-color: var(--c-border-strong); transform: translateY(-2px); }

/* ─── Callout ─────────────────────────────────────────────────────── */
.callout {
  border-left: 3px solid var(--c-gold);
  padding: 1.25rem 1.75rem;
  background: rgba(245,158,11,0.06);
  border-radius: 0 var(--radius) var(--radius) 0;
  margin: 2rem 0;
}
.callout p { font-size: 1.05rem; color: var(--c-parchment); max-width: none; }
.callout-teal {
  border-left-color: var(--c-teal);
  background: rgba(56,189,248,0.06);
}
.callout-amber {
  border-left-color: var(--c-gold);
  background: rgba(245,158,11,0.06);
}

/* ─── Pull quote ─────────────────────────────────────────────────── */
.pull-quote {
  font-family: var(--f-title);
  font-size: clamp(1.1rem, 2vw, 1.35rem);
  font-weight: 600;
  color: var(--c-teal);
  line-height: 1.4;
  padding: 2rem 0;
  border-top: 1px solid var(--c-border);
  border-bottom: 1px solid var(--c-border);
  margin: 2.5rem 0;
  letter-spacing: 0.01em;
}

/* ─── Grids ──────────────────────────────────────────────────────── */
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 1.5rem; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.25rem; }
.grid-auto { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 1.25rem; }
@media (max-width: 700px) {
  .grid-2, .grid-3 { grid-template-columns: 1fr; }
  .site-nav .nav-links { display: none; }
}

/* ─── Tag pills ──────────────────────────────────────────────────── */
.tag {
  display: inline-block;
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 0.25rem 0.65rem;
  border-radius: 999px;
  font-family: var(--f-body);
  font-weight: 500;
}
.tag-gold  { background: rgba(245,158,11,0.12); color: var(--c-gold);  border: 1px solid rgba(245,158,11,0.3); }
.tag-teal  { background: rgba(56,189,248,0.12); color: var(--c-teal);  border: 1px solid rgba(56,189,248,0.3); }
.tag-amber { background: rgba(245,158,11,0.12); color: var(--c-gold); border: 1px solid rgba(245,158,11,0.3); }

/* ─── Images ─────────────────────────────────────────────────────── */
.full-image {
  width: 100%;
  border-radius: var(--radius-lg);
  border: 1px solid var(--c-border);
  display: block;
  margin: 2.5rem 0;
}

/* ─── Cover (home page) ──────────────────────────────────────────── */
.cover {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: flex-end;
  overflow: hidden;
}
.cover-bg {
  position: absolute;
  inset: 0;
  background-size: cover;
  background-position: center top;
  filter: brightness(0.38);
}
.cover-gradient {
  position: absolute;
  inset: 0;
  background: linear-gradient(
    to bottom,
    rgba(10,14,23,0.15) 0%,
    rgba(10,14,23,0.0)  35%,
    rgba(10,14,23,0.65) 70%,
    rgba(10,14,23,1.0)  100%
  );
}
.cover-content {
  position: relative;
  z-index: 2;
  width: 100%;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 2rem 7rem;
}
.cover-eyebrow {
  font-family: var(--f-body);
  font-size: 0.7rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--c-teal);
  margin-bottom: 1.2rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}
.cover-eyebrow::before {
  content: '';
  display: inline-block;
  width: 2rem; height: 1px;
  background: var(--c-teal);
}
.cover-tagline {
  font-family: var(--f-prose);
  font-size: 1.2rem;
  font-style: italic;
  color: var(--c-parchment-dim);
  margin: 1rem 0 2.5rem;
  max-width: 55ch;
}
.cover-meta { display: flex; gap: 3rem; flex-wrap: wrap; }
.meta-item { display: flex; flex-direction: column; gap: 0.2rem; }
.meta-label {
  font-size: 0.68rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--c-teal-dim);
}
.meta-value {
  font-family: var(--f-title);
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--c-parchment);
}

/* ─── Stats ──────────────────────────────────────────────────────── */
.stat-row {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  padding: 2rem 0;
  border-top: 1px solid var(--c-border);
  border-bottom: 1px solid var(--c-border);
  margin: 2.5rem 0;
}
.stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  flex: 1;
  min-width: 100px;
}
.stat-value {
  font-family: var(--f-title);
  font-size: 2rem;
  font-weight: 800;
  color: var(--c-teal);
  line-height: 1;
}
.stat-label {
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--c-parchment-dim);
  margin-top: 0.4rem;
}

/* ─── Research card (index page) ─────────────────────────────────── */
.research-card {
  background: var(--c-bg-card);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  position: relative;
  overflow: hidden;
  transition: border-color 0.25s, transform 0.2s;
  display: flex;
  flex-direction: column;
  cursor: pointer;
}
.research-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 3px; height: 100%;
  background: var(--c-teal);
}
.research-card:hover { border-color: var(--c-border-strong); transform: translateY(-2px); }
.research-num {
  font-family: var(--f-title);
  font-size: 0.65rem;
  letter-spacing: 0.18em;
  color: var(--c-teal-dim);
  margin-bottom: 0.5rem;
}
.research-title {
  font-family: var(--f-title);
  font-size: 1rem;
  font-weight: 700;
  color: var(--c-parchment);
  margin-bottom: 0.75rem;
}
.research-intro {
  font-family: var(--f-prose);
  font-size: 0.98rem;
  color: var(--c-parchment-dim);
  line-height: 1.65;
  flex: 1;
}
.research-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 1.25rem;
}
.research-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-teal);
  text-decoration: none;
  transition: color 0.2s, gap 0.2s;
}
.research-link:hover { color: var(--c-gold); gap: 0.65rem; }

/* ─── Source count badge ─────────────────────────────────────────── */
.source-count {
  font-family: var(--f-body);
  font-size: 0.62rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--c-teal-dim);
  padding: 0.2rem 0.55rem;
  border: 1px solid rgba(56,189,248,0.25);
  border-radius: 999px;
  white-space: nowrap;
}

/* ─── Pillar ─────────────────────────────────────────────────────── */
.pillar {
  background: var(--c-bg-card);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  transition: border-color 0.25s, background 0.25s;
}
.pillar:hover { border-color: var(--c-border-strong); background: var(--c-bg-lift); }
.pillar-num {
  font-family: var(--f-title);
  font-size: 1.8rem;
  font-weight: 800;
  color: rgba(56,189,248,0.2);
  line-height: 1;
}
.pillar-title {
  font-family: var(--f-title);
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--c-parchment);
  letter-spacing: 0.02em;
}
.pillar-body {
  font-family: var(--f-prose);
  font-size: 0.92rem;
  color: var(--c-parchment-dim);
  line-height: 1.55;
}

/* ─── Gap cards ──────────────────────────────────────────────────── */
.gap-card {
  background: var(--c-bg-card);
  border: 1px solid rgba(245,158,11,0.2);
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  display: flex; gap: 0.75rem; align-items: flex-start;
}
.gap-icon { color: var(--c-gold); font-size: 0.8rem; margin-top: 0.2rem; flex-shrink: 0; }
.gap-text { font-family: var(--f-prose); font-size: 0.96rem; color: var(--c-parchment-dim); }

/* ─── Gold rule ──────────────────────────────────────────────────── */
.gold-rule {
  display: flex; align-items: center; gap: 1rem;
  margin: 3rem 0;
}
.gold-rule::before, .gold-rule::after {
  content: ''; flex: 1; height: 1px; background: var(--c-border-strong);
}
.gold-rule-icon { width: 8px; height: 8px; background: var(--c-teal); transform: rotate(45deg); flex-shrink: 0; }

/* ─── Blockquote ─────────────────────────────────────────────────── */
blockquote {
  border-left: 3px solid var(--c-teal);
  padding: 1rem 1.5rem;
  background: rgba(56,189,248,0.04);
  border-radius: 0 var(--radius) var(--radius) 0;
  margin: 2rem 0;
  font-family: var(--f-prose);
  font-size: 1.05rem;
  color: var(--c-parchment-dim);
  font-style: italic;
}
blockquote small { font-style: normal; font-size: 0.85rem; color: var(--c-teal-dim); }

/* ─── Footer ─────────────────────────────────────────────────────── */
footer {
  padding: 3rem 2rem;
  border-top: 1px solid var(--c-border);
  text-align: center;
}
.footer-logo {
  font-family: var(--f-title);
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--c-teal-dim);
  margin-bottom: 0.5rem;
}
footer p {
  font-size: 0.78rem;
  color: var(--c-parchment-dim);
  opacity: 0.45;
  text-align: center;
  max-width: none;
}

/* ─── Prose sections ─────────────────────────────────────────────── */
.prose-section {
  max-width: 72ch;
  margin: 2.5rem auto 3.5rem;
}
.prose-section p + p { margin-top: 1.1rem; }

.insight-block {
  background: var(--c-bg-card);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  margin: 2rem 0;
}
.insight-block h3 { margin-bottom: 1rem; }

.application-block {
  border-left: 3px solid var(--c-teal);
  padding: 1rem 1.5rem;
  background: rgba(56,189,248,0.05);
  border-radius: 0 var(--radius) var(--radius) 0;
  margin: 1.5rem 0;
}
.application-block p { color: var(--c-parchment); max-width: none; }

/* ─── Findings helpers ───────────────────────────────────────────── */
.findings-heading {
  font-size: 0.75rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--c-teal);
  margin-bottom: 1.25rem;
}
.findings-list {
  padding-left: 1.25rem;
  font-family: var(--f-prose);
  font-size: 1rem;
  line-height: 1.8;
}
.findings-list li { margin-bottom: 0.75rem; color: var(--c-parchment-dim); }
.findings-list strong { color: var(--c-parchment); }

/* ─── Inline citation ────────────────────────────────────────────── */
.cite-ref { font-size: 0.7em; vertical-align: super; line-height: 0; }
.cite-ref a { color: var(--c-teal); text-decoration: none; }

/* ─── Font size classes ──────────────────────────────────────────── */
html.font-sm  { font-size: 14px; }
html.font-md  { font-size: 16px; }
html.font-lg  { font-size: 18px; }
html.font-xl  { font-size: 20px; }

/* ═══════════════════════════════════════════════════════════════════
   Hub & Spoke Addendum
   ═══════════════════════════════════════════════════════════════════ */

/* ─── Research page bottom navigation ───────────────────────────── */
.research-page-nav {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 1.5rem;
  padding: 2.5rem 0;
  border-top: 1px solid var(--c-border);
  margin-top: 4rem;
}
.rpn-prev, .rpn-next {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  text-decoration: none;
  padding: 1rem 1.25rem;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  background: var(--c-bg-card);
  transition: border-color 0.2s, background 0.2s;
  cursor: pointer;
}
.rpn-prev:hover, .rpn-next:hover {
  border-color: var(--c-border-strong);
  background: var(--c-bg-lift);
}
.rpn-prev { align-items: flex-start; }
.rpn-next { align-items: flex-end; text-align: right; }
.rpn-label {
  font-size: 0.65rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--c-teal-dim);
  font-family: var(--f-body);
}
.rpn-title {
  font-family: var(--f-title);
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--c-parchment);
  letter-spacing: 0.02em;
}
.rpn-home {
  text-align: center;
  font-size: 0.7rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--c-teal-dim);
  text-decoration: none;
  padding: 0.6rem 1rem;
  border: 1px solid var(--c-border);
  border-radius: 999px;
  white-space: nowrap;
  transition: color 0.2s, border-color 0.2s;
  font-family: var(--f-body);
  cursor: pointer;
}
.rpn-home:hover { color: var(--c-teal); border-color: var(--c-border-strong); }
.rpn-empty { visibility: hidden; pointer-events: none; }
@media (max-width: 600px) {
  .research-page-nav { grid-template-columns: 1fr 1fr; }
  .rpn-home { grid-column: 1 / -1; order: -1; }
}

/* ─── Font Size Widget ──────────────────────────────────────────── */
.font-size-widget {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  z-index: 99;
  display: flex;
  gap: 0.25rem;
  background: var(--c-bg-card);
  border: 1px solid var(--c-border);
  border-radius: 999px;
  padding: 0.35rem 0.5rem;
  backdrop-filter: blur(8px);
}
.font-size-btn {
  width: 2rem; height: 2rem;
  border: 1px solid var(--c-border);
  border-radius: 50%;
  background: transparent;
  color: var(--c-parchment-dim);
  font-family: var(--f-body);
  font-size: 0.75rem;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: color 0.2s, border-color 0.2s, background 0.2s;
}
.font-size-btn:hover {
  color: var(--c-teal);
  border-color: var(--c-teal-dim);
  background: rgba(56,189,248,0.08);
}
.font-size-btn.active {
  color: var(--c-teal);
  border-color: var(--c-teal);
  background: rgba(56,189,248,0.12);
}

/* ─── Findings Block ─────────────────────────────────────────────── */
.findings-block {
  padding: 4rem 0;
  border-top: 1px solid var(--c-border);
}

/* ─── Sources Section ───────────────────────────────────────────── */
.sources-section {
  padding: 3rem 0;
  border-top: 1px solid var(--c-border);
}
.sources-list {
  list-style: decimal;
  padding-left: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  max-width: 72ch;
}
.sources-list li {
  font-family: var(--f-prose);
  font-size: 0.92rem;
  color: var(--c-parchment-dim);
  line-height: 1.5;
}
.sources-list a {
  color: var(--c-teal);
  text-decoration: none;
  border-bottom: 1px dotted var(--c-teal-dim);
  transition: color 0.2s, border-color 0.2s;
}
.sources-list a:hover { color: var(--c-gold); border-bottom-color: var(--c-gold); }

/* ─── Research Hero Image ────────────────────────────────────────── */
.research-hero { max-width: var(--max-w); margin: 0 auto; padding: 0 2rem; }
.research-hero img {
  width: 100%;
  border-radius: var(--radius-lg);
  border: 1px solid var(--c-border);
  display: block;
}

/* ─── Concept card extra info (hub page) ─────────────────────────── */
.card-mechanic {
  font-size: 0.62rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-teal-dim);
  margin-bottom: 0.4rem;
  font-family: var(--f-body);
}
.card-hook {
  font-family: var(--f-prose);
  font-style: italic;
  font-size: 0.95rem;
  color: var(--c-parchment-dim);
  margin-bottom: 0.75rem;
  line-height: 1.5;
}
.card-meta-row {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  margin-top: 0.5rem;
  margin-bottom: 0.75rem;
}
.card-meta-item {
  font-size: 0.68rem;
  letter-spacing: 0.06em;
  color: var(--c-parchment-dim);
  font-family: var(--f-body);
}
.card-meta-item strong {
  color: var(--c-teal);
  font-weight: 600;
}
.card-disambiguation {
  font-size: 0.72rem;
  font-family: var(--f-body);
  color: var(--c-parchment-dim);
  background: rgba(56,189,248,0.04);
  border: 1px solid rgba(56,189,248,0.15);
  border-radius: var(--radius);
  padding: 0.55rem 0.8rem;
  margin-top: 0.5rem;
  margin-bottom: 0.75rem;
  line-height: 1.55;
}
.card-disambiguation em {
  color: var(--c-teal);
  font-style: normal;
  font-weight: 600;
}

/* ─── Lessons learned section ────────────────────────────────────── */
#lessons-learned {
  background: var(--c-bg-alt);
}
#lessons-learned h2 { color: var(--c-teal); }