/* ================================================================
   NORBERT BUTARE — RESEARCH SITE
   Black & White Editorial Design System
   ================================================================ */

@import url('https://fonts.googleapis.com/css2?family=Cormorant:ital,wght@0,300;0,400;0,500;0,600;0,700;1,300;1,400;1,500;1,600&family=Barlow:wght@300;400;500;600;700&family=Barlow+Condensed:wght@400;500;600;700&family=IBM+Plex+Mono:wght@400;500&display=swap');

/* ---- Tokens ---- */
:root {
  /* Base */
  --bg:           #f7f7f7;
  --bg-alt:       #efefef;
  --surface:      #ffffff;
  --surface-soft: #fafafa;
  --border:       #dcdcdc;
  --border-soft:  #e8e8e8;

  /* Ink */
  --ink:          #0a0a0a;
  --ink-2:        #1c1c1c;
  --ink-3:        #484848;
  --ink-muted:    #787878;

  /* Brand — black */
  --brand:        #0a0a0a;
  --brand-dark:   #000000;
  --brand-light:  #f0f0f0;
  --brand-mid:    #bebebe;

  /* Accent */
  --amber:        #333333;
  --amber-light:  #f0f0f0;

  /* Category colours — monochrome differentiated */
  --ai-color:       #0a0a0a;
  --ai-light:       #f0f0f0;
  --ai-mid:         #c0c0c0;

  --energy-color:   #0a0a0a;
  --energy-light:   #ffffff;
  --energy-mid:     #0a0a0a;

  --mkt-color:      #333333;
  --mkt-light:      #f0f0f0;
  --mkt-mid:        #bbbbbb;

  /* Hero dark */
  --hero-bg:      #000000;
  --hero-2:       #111111;
  --hero-text:    #f0f0f0;
  --hero-muted:   #888888;

  /* Shadows */
  --shadow-sm:    0 1px 6px rgba(0,0,0,0.06), 0 2px 12px rgba(0,0,0,0.04);
  --shadow-md:    0 4px 20px rgba(0,0,0,0.09), 0 1px 4px rgba(0,0,0,0.05);
  --shadow-lg:    0 12px 40px rgba(0,0,0,0.12);

  /* Radii */
  --r-sm:  5px;
  --r-md:  10px;
  --r-lg:  16px;
  --r-xl:  22px;

  /* Typography */
  --serif:     'Cormorant', Georgia, serif;
  --sans:      'Barlow', 'Segoe UI', sans-serif;
  --condensed: 'Barlow Condensed', 'Arial Narrow', sans-serif;
  --mono:      'IBM Plex Mono', ui-monospace, monospace;
}

/* ---- Reset ---- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 1.0625rem;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}
img, svg { display: block; max-width: 100%; }
a { color: var(--brand); text-decoration: underline; text-underline-offset: 3px; text-decoration-thickness: 1.5px; }
a:hover { color: #333; }
button { cursor: pointer; font-family: var(--sans); }

/* ================================================================
   GLOBAL NAV
   ================================================================ */

.site-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(0, 0, 0, 0.97);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(255,255,255,0.08);
}

.nav-inner {
  max-width: 1360px;
  margin: 0 auto;
  padding: 0 1.5rem;
  height: 58px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
}

.nav-logo-mark {
  width: 34px; height: 34px;
  border-radius: var(--r-sm);
  background: transparent;
  border: 1.5px solid rgba(255,255,255,0.35);
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0;
  font-family: var(--serif);
  font-weight: 700;
  font-size: 1.1rem;
  color: #ffffff;
  letter-spacing: -0.02em;
}

.nav-logo-text {
  display: flex;
  flex-direction: column;
  line-height: 1.1;
}

.nav-logo-name {
  font-family: var(--serif);
  font-weight: 600;
  font-size: 1rem;
  color: var(--hero-text);
  letter-spacing: 0.01em;
}

.nav-logo-sub {
  font-family: var(--condensed);
  font-size: 0.62rem;
  color: rgba(255,255,255,0.45);
  text-transform: uppercase;
  letter-spacing: 0.14em;
  font-weight: 600;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.15rem;
  list-style: none;
}

.nav-links a {
  display: inline-flex;
  align-items: center;
  padding: 0.35rem 0.72rem;
  border-radius: var(--r-sm);
  color: rgba(240,240,240,0.55);
  font-family: var(--condensed);
  font-size: 0.88rem;
  font-weight: 500;
  text-decoration: none;
  transition: color 0.15s, background 0.15s;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--hero-text);
  background: rgba(255,255,255,0.08);
}

.nav-links a.active {
  color: #ffffff;
}

.nav-cta {
  background: rgba(255,255,255,0.12) !important;
  color: #fff !important;
  border: 1px solid rgba(255,255,255,0.25) !important;
}

.nav-cta:hover {
  background: rgba(255,255,255,0.2) !important;
}

/* ================================================================
   UTILITY CLASSES
   ================================================================ */

.container {
  max-width: 1360px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.container-narrow {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.section { padding: 5rem 0; }
.section-sm { padding: 3rem 0; }

.tag {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-family: var(--condensed);
  font-size: 0.68rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  padding: 0.22rem 0.58rem;
  border-radius: 3px;
}

/* B&W differentiated tags */
.tag-ai    { background: #f0f0f0; color: #111; border: 1px solid #c8c8c8; }
.tag-energy { background: #111; color: #fff; }
.tag-mkt   { background: #555; color: #fff; }
.tag-brand { background: #f0f0f0; color: #111; border: 1px solid #c8c8c8; }

.divider {
  border: none;
  border-top: 1px solid var(--border);
  margin: 0;
}

/* ================================================================
   PAPER CARDS
   ================================================================ */

.paper-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 1.75rem;
  box-shadow: var(--shadow-sm);
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
  display: flex;
  flex-direction: column;
  gap: 0.9rem;
  text-decoration: none;
  color: inherit;
  position: relative;
  overflow: hidden;
}

.paper-card::before {
  content: '';
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 2px;
  background: var(--ink);
  transform: scaleY(0);
  transform-origin: bottom;
  transition: transform 0.22s ease;
}

.paper-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: #aaa;
  color: inherit;
  text-decoration: none;
}

.paper-card:hover::before {
  transform: scaleY(1);
}

.paper-card-meta {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  flex-wrap: wrap;
}

.paper-card-date {
  font-family: var(--condensed);
  font-size: 0.76rem;
  color: var(--ink-muted);
  font-weight: 500;
  letter-spacing: 0.04em;
}

.paper-card-title {
  font-family: var(--serif);
  font-weight: 600;
  font-size: 1.25rem;
  color: var(--ink);
  line-height: 1.22;
}

.paper-card-excerpt {
  font-size: 0.975rem;
  color: var(--ink-3);
  line-height: 1.65;
  flex: 1;
}

.paper-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 0.6rem;
  border-top: 1px solid var(--border-soft);
  font-size: 0.84rem;
  color: var(--ink-muted);
}

.paper-card-read {
  color: var(--ink);
  font-weight: 700;
  font-family: var(--condensed);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  display: flex;
  align-items: center;
  gap: 0.3rem;
}

.paper-card-coming {
  border-style: dashed;
  opacity: 0.6;
  cursor: default;
}
.paper-card-coming::before { display: none; }
.paper-card-coming:hover {
  transform: none;
  box-shadow: var(--shadow-sm);
  border-color: var(--border);
}

/* ================================================================
   ARTICLE CARDS
   ================================================================ */

.article-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 1.75rem;
  box-shadow: var(--shadow-sm);
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  text-decoration: none;
  color: inherit;
  position: relative;
  overflow: hidden;
}

.article-card::after {
  content: '';
  position: absolute;
  right: 0; top: 0; bottom: 0;
  width: 2px;
  background: var(--ink);
  transform: scaleY(0);
  transform-origin: top;
  transition: transform 0.22s ease;
}

.article-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: #aaa;
  color: inherit;
  text-decoration: none;
}

.article-card:hover::after {
  transform: scaleY(1);
}

.article-card-meta {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  flex-wrap: wrap;
}

.article-type {
  font-family: var(--condensed);
  font-size: 0.66rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--ink-muted);
  border: 1px solid var(--border);
  padding: 0.18rem 0.45rem;
  border-radius: 3px;
}

.article-read-time {
  font-family: var(--mono);
  font-size: 0.7rem;
  color: var(--ink-muted);
  margin-left: auto;
}

.article-card-title {
  font-family: var(--serif);
  font-weight: 600;
  font-size: 1.2rem;
  color: var(--ink);
  line-height: 1.25;
}

.article-card-excerpt {
  font-size: 0.975rem;
  color: var(--ink-3);
  line-height: 1.65;
  flex: 1;
}

.article-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 0.6rem;
  border-top: 1px solid var(--border-soft);
  font-family: var(--condensed);
  font-size: 0.78rem;
  color: var(--ink-muted);
  letter-spacing: 0.04em;
}

.article-card-read {
  color: var(--ink);
  font-weight: 700;
  font-family: var(--condensed);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

.article-card-coming {
  border-style: dashed;
  opacity: 0.6;
  cursor: default;
}
.article-card-coming::after { display: none; }
.article-card-coming:hover {
  transform: none;
  box-shadow: var(--shadow-sm);
  border-color: var(--border);
}

/* Articles grid */
.articles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 1.5rem;
}

/* ================================================================
   CATEGORY SECTION PILLARS
   ================================================================ */

.pillar-card {
  border-radius: var(--r-xl);
  padding: 2rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  text-decoration: none;
  color: inherit;
}

.pillar-card:hover { transform: translateY(-4px); }
.pillar-card:hover { text-decoration: none; color: inherit; }

.pillar-icon {
  width: 52px; height: 52px;
  border-radius: 12px;
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0;
}

/* AI: light bg, dark text */
.pillar-card-ai {
  background: #f5f5f5;
  border: 1.5px solid #d0d0d0;
  box-shadow: var(--shadow-sm);
}
.pillar-icon-ai { background: #e8e8e8; color: #111; }
.pillar-label-ai { color: #333; }
.pillar-count-ai { color: #333; }

/* Energy: black bg, white text */
.pillar-card-energy {
  background: #0a0a0a;
  border: 1.5px solid #111;
  box-shadow: var(--shadow-md);
  color: #f0f0f0;
}
.pillar-icon-energy { background: rgba(255,255,255,0.1); color: #f0f0f0; }
.pillar-label-energy { color: rgba(255,255,255,0.55); }
.pillar-count-energy { color: rgba(255,255,255,0.55); }
.pillar-card-energy .pillar-title { color: #f0f0f0; }
.pillar-card-energy .pillar-desc  { color: rgba(240,240,240,0.68); }
.pillar-card-energy:hover { box-shadow: 0 16px 48px rgba(0,0,0,0.35); }

/* Marketing: white bg, medium border */
.pillar-card-mkt {
  background: #ffffff;
  border: 1.5px solid #bbbbbb;
  box-shadow: var(--shadow-sm);
}
.pillar-icon-mkt { background: #f0f0f0; color: #333; }
.pillar-label-mkt { color: #555; }
.pillar-count-mkt { color: #555; }

.pillar-label {
  font-family: var(--condensed);
  font-size: 0.66rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.14em;
}

.pillar-title {
  font-family: var(--serif);
  font-weight: 700;
  font-size: 1.45rem;
  color: var(--ink);
  line-height: 1.18;
}

.pillar-desc {
  font-size: 0.975rem;
  color: var(--ink-3);
  line-height: 1.62;
}

.pillar-count {
  font-family: var(--condensed);
  font-size: 0.76rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-top: auto;
}

/* ================================================================
   SECTION HEADERS
   ================================================================ */

.section-header {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 2.5rem;
  flex-wrap: wrap;
}

.section-eyebrow {
  font-family: var(--condensed);
  font-size: 0.68rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.18em;
  color: var(--ink-muted);
  margin-bottom: 0.4rem;
}

.section-title {
  font-family: var(--serif);
  font-weight: 700;
  font-size: clamp(1.9rem, 3vw, 2.7rem);
  color: var(--ink);
  line-height: 1.08;
}

.section-subtitle {
  color: var(--ink-3);
  font-size: 1.05rem;
  margin-top: 0.55rem;
  max-width: 540px;
  line-height: 1.65;
}

.section-link {
  font-family: var(--condensed);
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--ink);
  text-decoration: none;
  white-space: nowrap;
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  border-bottom: 1.5px solid var(--ink);
  padding-bottom: 1px;
}
.section-link:hover { color: #444; border-color: #444; text-decoration: none; }

/* ================================================================
   FOOTER
   ================================================================ */

.site-footer {
  background: #000;
  color: #888;
  padding: 3.5rem 0 2rem;
  border-top: 1px solid rgba(255,255,255,0.06);
}

.footer-inner {
  max-width: 1360px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr;
  gap: 3rem;
  padding-bottom: 2.5rem;
  border-bottom: 1px solid rgba(255,255,255,0.07);
}

.footer-brand-name {
  font-family: var(--serif);
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--hero-text);
  margin-bottom: 0.5rem;
}

.footer-brand-desc {
  font-size: 0.9rem;
  line-height: 1.65;
  max-width: 280px;
}

.footer-col-title {
  font-family: var(--condensed);
  font-size: 0.66rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: rgba(255,255,255,0.3);
  margin-bottom: 1rem;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
}

.footer-links a {
  color: #888;
  font-size: 0.9rem;
  text-decoration: none;
  transition: color 0.15s;
}
.footer-links a:hover { color: #f0f0f0; }

.footer-bottom {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1.5rem;
  padding-top: 1.5rem;
  font-size: 0.83rem;
  flex-wrap: wrap;
}

.footer-bottom a {
  color: rgba(255,255,255,0.55);
}
.footer-bottom a:hover { color: rgba(255,255,255,0.9); }

.footer-affilations {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  flex-wrap: wrap;
}

.footer-affil-link {
  color: rgba(255,255,255,0.3);
  font-family: var(--condensed);
  font-size: 0.74rem;
  text-decoration: none;
  border: 1px solid rgba(255,255,255,0.1);
  padding: 0.28rem 0.7rem;
  border-radius: var(--r-sm);
  transition: border-color 0.15s, color 0.15s;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.footer-affil-link:hover {
  border-color: rgba(255,255,255,0.35);
  color: rgba(255,255,255,0.75);
}

/* ================================================================
   CATEGORY PAGE HERO
   ================================================================ */

.cat-hero {
  padding: 5rem 0 4rem;
  border-bottom: 1px solid var(--border);
  background: var(--surface);
}

.cat-hero-inner {
  max-width: 1360px;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  gap: 3rem;
  flex-wrap: wrap;
}

.cat-hero-icon {
  width: 80px; height: 80px;
  border-radius: 20px;
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0;
}

.cat-hero-content { flex: 1; min-width: 260px; }

.cat-hero-eyebrow {
  font-family: var(--condensed);
  font-size: 0.68rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.16em;
  margin-bottom: 0.6rem;
  color: var(--ink-muted);
}

.cat-hero-title {
  font-family: var(--serif);
  font-weight: 700;
  font-size: clamp(2.2rem, 4.5vw, 3.6rem);
  line-height: 1.05;
  color: var(--ink);
  margin-bottom: 0.8rem;
}

.cat-hero-desc {
  color: var(--ink-3);
  font-size: 1.1rem;
  line-height: 1.65;
  max-width: 600px;
}

.cat-hero-stats {
  display: flex;
  gap: 2rem;
  margin-top: 1.5rem;
  flex-wrap: wrap;
}

.cat-stat-val {
  font-family: var(--serif);
  font-size: 2rem;
  font-weight: 700;
  color: var(--ink);
  line-height: 1;
}

.cat-stat-lbl {
  font-family: var(--condensed);
  font-size: 0.72rem;
  color: var(--ink-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-weight: 600;
  margin-top: 0.25rem;
}

/* ================================================================
   PAPER DETAIL PAGE
   ================================================================ */

.paper-topbar {
  border-bottom: 1px solid var(--border);
  background: var(--surface);
  padding: 0.9rem 0;
}

.paper-topbar-inner {
  max-width: 1360px;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  gap: 1.2rem;
  flex-wrap: wrap;
  justify-content: space-between;
}

.paper-breadcrumb {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--condensed);
  font-size: 0.84rem;
  color: var(--ink-muted);
  letter-spacing: 0.04em;
}

.paper-breadcrumb a {
  color: var(--ink-muted);
  text-decoration: none;
  transition: color 0.15s;
}
.paper-breadcrumb a:hover { color: var(--ink); }

.paper-breadcrumb-sep { opacity: 0.4; }

.paper-layout {
  max-width: 1360px;
  margin: 0 auto;
  padding: 2rem 1.5rem 5rem;
  display: grid;
  grid-template-columns: 260px minmax(0, 1fr);
  gap: 2rem;
  align-items: start;
}

.paper-sidebar {
  position: sticky;
  top: 80px;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.sidebar-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.sidebar-panel-head {
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border);
  background: var(--surface-soft);
  font-family: var(--condensed);
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--ink-3);
}

.sidebar-panel-body {
  padding: 0.85rem;
}

.paper-stats-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem;
}

.paper-stat {
  background: var(--bg);
  border-radius: var(--r-sm);
  padding: 0.6rem 0.65rem;
  border: 1px solid var(--border-soft);
}

.paper-stat b {
  display: block;
  font-family: var(--serif);
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--ink);
  line-height: 1.1;
  margin-bottom: 0.2rem;
}

.paper-stat span {
  font-family: var(--condensed);
  font-size: 0.66rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--ink-muted);
  font-weight: 700;
}

.toc-nav {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
  max-height: calc(100vh - 380px);
  overflow-y: auto;
  padding-right: 0.2rem;
  scrollbar-width: thin;
  scrollbar-color: var(--border) transparent;
}

.toc-nav a {
  display: block;
  padding: 0.35rem 0.5rem;
  border-radius: var(--r-sm);
  font-size: 0.875rem;
  color: var(--ink-3);
  text-decoration: none;
  line-height: 1.35;
  transition: background 0.12s, color 0.12s;
}

.toc-nav a:hover {
  background: var(--bg-alt);
  color: var(--ink);
}

.toc-nav a.level-3 {
  padding-left: 1.1rem;
  font-size: 0.82rem;
  color: var(--ink-muted);
}

/* Main report article */
.paper-article {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: clamp(1.75rem, 3vw, 2.75rem);
  box-shadow: var(--shadow-sm);
  min-height: 70vh;
}

.paper-article h1,
.paper-article h2,
.paper-article h3,
.paper-article h4 {
  font-family: var(--serif);
  color: var(--ink);
  line-height: 1.2;
}

.paper-article h1 {
  font-size: clamp(1.9rem, 3vw, 2.6rem);
  margin: 0 0 1.4rem;
  padding-bottom: 0.8rem;
  border-bottom: 2px solid var(--border);
}

.paper-article h2 {
  font-size: clamp(1.4rem, 2.2vw, 1.9rem);
  margin: 2.5rem 0 0.8rem;
}

.paper-article h3 {
  font-size: clamp(1.15rem, 1.8vw, 1.4rem);
  margin: 1.8rem 0 0.6rem;
}

.paper-article p,
.paper-article li {
  color: var(--ink-2);
  font-size: 1.05rem;
  line-height: 1.78;
}

.paper-article ul,
.paper-article ol {
  padding-left: 1.4rem;
  margin: 0.5rem 0;
}

.paper-article strong { color: var(--ink); }

.paper-article code {
  font-family: var(--mono);
  font-size: 0.87em;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0.06rem 0.3rem;
}

.paper-article pre {
  margin: 1.2rem 0;
  border-radius: var(--r-md);
  border: 1px solid var(--border);
  background: var(--bg);
  padding: 1.2rem;
  overflow: auto;
}

.paper-article pre code {
  border: 0; background: transparent; padding: 0;
  font-size: 0.85rem; line-height: 1.55; color: var(--ink-2);
}

.table-wrap {
  overflow: auto;
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  margin: 1.2rem 0;
  box-shadow: var(--shadow-sm);
}

table {
  width: 100%;
  border-collapse: collapse;
  min-width: 640px;
  font-size: 0.95rem;
}

th, td {
  border: 1px solid var(--border);
  padding: 0.65rem 0.8rem;
  text-align: left;
  vertical-align: top;
}

th {
  background: var(--bg-alt);
  color: var(--ink-2);
  font-weight: 700;
  font-family: var(--condensed);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.07em;
}

tr:nth-child(even) td { background: var(--surface-soft); }

.visual-card {
  margin: 1.2rem 0 1.4rem;
  padding: 1.2rem;
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  background: var(--surface-soft);
  box-shadow: var(--shadow-sm);
  overflow: auto;
}

.mermaid-fallback {
  font-size: 0.88rem;
  color: var(--ink-muted);
  margin-bottom: 0.5rem;
}

.source-register { margin: 1.2rem 0; }

.back-to-top {
  position: fixed;
  bottom: 1.5rem; right: 1.5rem;
  width: 42px; height: 42px;
  background: var(--ink);
  color: #fff;
  border: none;
  border-radius: 50%;
  font-size: 1rem;
  box-shadow: var(--shadow-md);
  display: flex; align-items: center; justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s, background 0.15s;
  z-index: 90;
}

.back-to-top.visible {
  opacity: 1;
  pointer-events: auto;
}

.back-to-top:hover { background: #333; }

/* ================================================================
   RESPONSIVE
   ================================================================ */

@media (max-width: 1024px) {
  .paper-layout {
    grid-template-columns: 220px minmax(0, 1fr);
  }
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
  .footer-grid > *:first-child {
    grid-column: 1 / -1;
  }
}

@media (max-width: 768px) {
  .nav-links { display: none; }

  .paper-layout {
    grid-template-columns: 1fr;
  }

  .paper-sidebar {
    position: static;
  }

  .cat-hero { padding: 3rem 0 2.5rem; }
  .cat-hero-icon { width: 60px; height: 60px; }
  .section { padding: 3.5rem 0; }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }

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