/* ============================================
   algorithms.technology — Design System
   Protecting children in the age of AI
   ============================================ */

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

:root {
  /* Palette */
  --ink: #0f1419;
  --ink-light: #2c3e50;
  --ink-muted: #5a6a7a;
  --surface: #ffffff;
  --surface-alt: #f7f8fa;
  --surface-dark: #0f1419;
  --surface-dark-alt: #1a2332;
  --accent: #e74c3c;
  --accent-dark: #c0392b;
  --accent-warm: #e67e22;
  --blue: #2980b9;
  --blue-dark: #1a5276;
  --teal: #16a085;
  --border: #e1e5eb;
  --border-light: #f0f2f5;

  /* Type Scale */
  --font-display: 'DM Serif Display', Georgia, 'Times New Roman', serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'SF Mono', monospace;

  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1.0625rem;
  --text-lg: 1.25rem;
  --text-xl: 1.5rem;
  --text-2xl: 2rem;
  --text-3xl: 2.5rem;
  --text-4xl: 3.25rem;
  --text-5xl: 4rem;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;
  --space-4xl: 6rem;
  --space-5xl: 8rem;

  /* Layout */
  --content-width: 720px;
  --wide-width: 960px;
  --max-width: 1200px;

  /* Effects */
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.1);
  --shadow-lg: 0 8px 30px rgba(0,0,0,0.12);
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
}

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.7;
  color: var(--ink);
  background: var(--surface);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* --- Typography --- */
h1, h2, h3, h4 { font-family: var(--font-display); line-height: 1.2; letter-spacing: -0.01em; }
h1 { font-size: var(--text-4xl); font-weight: 400; }
h2 { font-size: var(--text-3xl); font-weight: 400; }
h3 { font-size: var(--text-2xl); font-weight: 400; }
h4 { font-size: var(--text-xl); font-weight: 400; }

p { margin-bottom: var(--space-lg); }
p:last-child { margin-bottom: 0; }

a { color: var(--blue); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--blue-dark); text-decoration: underline; }

strong { font-weight: 600; }

blockquote {
  border-left: 3px solid var(--accent);
  padding: var(--space-lg) var(--space-xl);
  margin: var(--space-2xl) 0;
  background: var(--surface-alt);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  font-size: var(--text-lg);
  color: var(--ink-light);
  font-style: italic;
}

blockquote cite {
  display: block;
  margin-top: var(--space-md);
  font-style: normal;
  font-size: var(--text-sm);
  color: var(--ink-muted);
  font-weight: 600;
}

/* --- Layout --- */
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 var(--space-xl); }
.container--narrow { max-width: var(--content-width); }
.container--wide { max-width: var(--wide-width); }

.section {
  padding: var(--space-4xl) 0;
}

.section--dark {
  background: var(--surface-dark);
  color: var(--surface);
}

.section--dark h2,
.section--dark h3,
.section--dark h4 {
  color: var(--surface);
}

.section--dark p,
.section--dark li {
  color: #c8d0da;
}

.section--alt {
  background: var(--surface-alt);
}

.section--accent {
  background: var(--accent);
  color: var(--surface);
}

.section--accent h2,
.section--accent h3,
.section--accent p {
  color: var(--surface);
}

/* --- Navigation --- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(15, 20, 25, 0.97);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(255,255,255,0.06);
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-xl);
  height: 64px;
}

.nav__brand {
  font-family: var(--font-mono);
  font-size: var(--text-base);
  color: var(--surface);
  text-decoration: none;
  letter-spacing: 0.02em;
  font-weight: 600;
  flex-shrink: 0;
}

.nav__brand:hover { color: var(--surface); text-decoration: none; }

.nav__brand span { color: var(--accent); }

.nav__links {
  display: flex;
  align-items: center;
  gap: 0;
  list-style: none;
  height: 100%;
}

.nav__links > li {
  height: 100%;
  display: flex;
  align-items: center;
}

.nav__links > li > a {
  color: rgba(255,255,255,0.55);
  font-size: var(--text-sm);
  font-weight: 500;
  text-decoration: none;
  transition: color 0.2s, background 0.2s;
  letter-spacing: 0.01em;
  padding: 0 var(--space-md);
  height: 100%;
  display: flex;
  align-items: center;
  position: relative;
}

.nav__links > li > a:hover {
  color: rgba(255,255,255,0.9);
  text-decoration: none;
}

.nav__links > li > a.active {
  color: var(--surface);
  text-decoration: none;
}

.nav__links > li > a.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: var(--space-md);
  right: var(--space-md);
  height: 2px;
  background: var(--accent);
  border-radius: 1px;
}

/* Separator between Evidence and the rest */
.nav__separator {
  width: 1px;
  height: 20px;
  background: rgba(255,255,255,0.1);
  margin: 0 var(--space-xs);
  flex-shrink: 0;
}

/* --- Nav Dropdown --- */
.nav__dropdown {
  position: relative;
  height: 100%;
  display: flex;
  align-items: center;
}

.nav__dropdown-toggle {
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
}

.nav__dropdown-toggle svg {
  width: 10px;
  height: 10px;
  opacity: 0.5;
  transition: transform 0.2s, opacity 0.2s;
}

.nav__dropdown:hover .nav__dropdown-toggle svg {
  transform: rotate(180deg);
  opacity: 0.8;
}

.nav__dropdown-menu {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  padding-top: 4px;
  min-width: 240px;
  list-style: none;
}

.nav__dropdown:hover .nav__dropdown-menu {
  display: block;
}

.nav__dropdown-menu-inner {
  background: rgba(15, 20, 25, 0.98);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: var(--radius-lg);
  padding: var(--space-sm) 0;
  box-shadow: 0 12px 40px rgba(0,0,0,0.4), 0 0 0 1px rgba(255,255,255,0.04);
}

.nav__dropdown-menu-inner ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.nav__dropdown-menu li a {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 10px var(--space-lg);
  color: rgba(255,255,255,0.55);
  font-size: var(--text-sm);
  font-weight: 400;
  text-decoration: none;
  transition: color 0.15s, background 0.15s;
  white-space: nowrap;
}

.nav__dropdown-menu li a:hover {
  color: var(--surface);
  background: rgba(255,255,255,0.05);
  text-decoration: none;
}

.nav__dropdown-menu li a.active {
  color: var(--surface);
  background: rgba(255,255,255,0.03);
  text-decoration: none;
}

.nav__dropdown-menu li a.active::before {
  content: '';
  display: inline-block;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--accent);
  margin-right: var(--space-xs);
  flex-shrink: 0;
}

/* --- Mobile Nav Toggle --- */
.nav__toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-sm);
  color: var(--surface);
}

.nav__toggle svg {
  width: 24px;
  height: 24px;
}

/* --- Mobile Nav --- */
.nav__mobile {
  display: none;
  position: fixed;
  top: 64px;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(15, 20, 25, 0.98);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  z-index: 99;
  padding: var(--space-xl);
  overflow-y: auto;
}

.nav__mobile.is-open {
  display: block;
}

.nav__mobile ul {
  list-style: none;
  padding: 0;
}

.nav__mobile > ul > li {
  border-bottom: 1px solid rgba(255,255,255,0.06);
}

.nav__mobile > ul > li > a {
  display: block;
  padding: var(--space-lg) 0;
  color: rgba(255,255,255,0.7);
  font-size: var(--text-lg);
  font-weight: 500;
  text-decoration: none;
}

.nav__mobile > ul > li > a.active,
.nav__mobile > ul > li > a:hover {
  color: var(--surface);
  text-decoration: none;
}

.nav__mobile-label {
  display: block;
  padding: var(--space-lg) 0 var(--space-sm);
  color: rgba(255,255,255,0.3);
  font-size: var(--text-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

.nav__mobile-sub {
  padding: 0 0 var(--space-md) var(--space-lg);
}

.nav__mobile-sub li a {
  display: block;
  padding: var(--space-sm) 0;
  color: rgba(255,255,255,0.5);
  font-size: var(--text-base);
  text-decoration: none;
}

.nav__mobile-sub li a:hover,
.nav__mobile-sub li a.active {
  color: var(--surface);
  text-decoration: none;
}

/* --- Hero --- */
.hero {
  padding: calc(var(--space-5xl) + 60px) 0 var(--space-5xl);
  background: var(--surface-dark);
  color: var(--surface);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0; bottom: 0;
  background:
    radial-gradient(ellipse at 20% 50%, rgba(231, 76, 60, 0.08) 0%, transparent 50%),
    radial-gradient(ellipse at 80% 20%, rgba(41, 128, 185, 0.06) 0%, transparent 50%);
  pointer-events: none;
}

.hero__content {
  position: relative;
  max-width: var(--wide-width);
  margin: 0 auto;
  padding: 0 var(--space-xl);
}

.hero__eyebrow {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--accent);
  margin-bottom: var(--space-lg);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.hero__eyebrow::before {
  content: '';
  display: inline-block;
  width: 24px;
  height: 2px;
  background: var(--accent);
}

.hero h1 {
  font-size: var(--text-5xl);
  margin-bottom: var(--space-xl);
  max-width: 800px;
}

.hero h1 em {
  font-style: normal;
  color: var(--accent);
}

.hero__subtitle {
  font-size: var(--text-xl);
  color: #8899aa;
  max-width: 640px;
  line-height: 1.6;
  margin-bottom: var(--space-2xl);
}

/* --- Stat Cards --- */
.stats-strip {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: var(--space-lg);
  margin: var(--space-3xl) 0;
}

.stat-card {
  background: var(--surface-dark-alt);
  border: 1px solid rgba(255,255,255,0.06);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  text-align: center;
}

.stat-card--light {
  background: var(--surface);
  border: 1px solid var(--border);
}

.stat-card__number {
  font-family: var(--font-display);
  font-size: var(--text-4xl);
  color: var(--accent);
  line-height: 1;
  margin-bottom: var(--space-sm);
}

.stat-card--light .stat-card__number {
  color: var(--accent);
}

.stat-card__label {
  font-size: var(--text-sm);
  color: #8899aa;
  line-height: 1.4;
}

.stat-card--light .stat-card__label {
  color: var(--ink-muted);
}

/* --- Content Cards --- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-xl);
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-2xl);
  transition: box-shadow 0.3s, transform 0.2s;
}

.card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.card--dark {
  background: var(--surface-dark-alt);
  border-color: rgba(255,255,255,0.06);
}

.card__icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: var(--space-lg);
}

.card__icon--red { background: rgba(231, 76, 60, 0.1); color: var(--accent); }
.card__icon--blue { background: rgba(41, 128, 185, 0.1); color: var(--blue); }
.card__icon--orange { background: rgba(230, 126, 34, 0.1); color: var(--accent-warm); }
.card__icon--teal { background: rgba(22, 160, 133, 0.1); color: var(--teal); }

.card h3 {
  font-size: var(--text-xl);
  margin-bottom: var(--space-md);
}

.card p {
  color: var(--ink-muted);
  font-size: var(--text-base);
}

/* --- Evidence Sections --- */
.evidence-block {
  padding: var(--space-3xl) 0;
  border-bottom: 1px solid var(--border);
}

.evidence-block:last-child {
  border-bottom: none;
}

.evidence-block__label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--accent);
  margin-bottom: var(--space-md);
}

.evidence-block h3 {
  margin-bottom: var(--space-lg);
}

.evidence-block h4 {
  font-size: var(--text-lg);
  margin: var(--space-2xl) 0 var(--space-md);
  color: var(--ink-light);
}

.evidence-block ul,
.evidence-block ol {
  padding-left: var(--space-xl);
  margin-bottom: var(--space-lg);
}

.evidence-block li {
  margin-bottom: var(--space-sm);
  color: var(--ink-light);
}

/* --- Warning Callout --- */
.callout {
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  margin: var(--space-2xl) 0;
}

.callout--danger {
  background: rgba(231, 76, 60, 0.06);
  border: 1px solid rgba(231, 76, 60, 0.15);
  border-left: 4px solid var(--accent);
}

.callout--info {
  background: rgba(41, 128, 185, 0.06);
  border: 1px solid rgba(41, 128, 185, 0.15);
  border-left: 4px solid var(--blue);
}

.callout--success {
  background: rgba(22, 160, 133, 0.06);
  border: 1px solid rgba(22, 160, 133, 0.15);
  border-left: 4px solid var(--teal);
}

.callout__title {
  font-family: var(--font-body);
  font-weight: 700;
  font-size: var(--text-base);
  margin-bottom: var(--space-sm);
}

.callout--danger .callout__title { color: var(--accent); }
.callout--info .callout__title { color: var(--blue); }
.callout--success .callout__title { color: var(--teal); }

/* --- Source List --- */
.sources {
  margin-top: var(--space-xl);
  padding-top: var(--space-lg);
  border-top: 1px solid var(--border-light);
}

.sources__title {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--ink-muted);
  margin-bottom: var(--space-sm);
}

.sources ul {
  list-style: none;
  padding: 0;
}

.sources li {
  font-size: var(--text-sm);
  color: var(--ink-muted);
  margin-bottom: var(--space-xs);
  padding-left: var(--space-lg);
  position: relative;
}

.sources li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.6em;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--border);
}

.sources a {
  color: var(--blue);
  font-size: var(--text-sm);
}

/* --- Comparison Table --- */
.comparison-table {
  width: 100%;
  border-collapse: collapse;
  margin: var(--space-2xl) 0;
  font-size: var(--text-sm);
}

.comparison-table th {
  font-family: var(--font-body);
  font-weight: 600;
  text-align: left;
  padding: var(--space-md) var(--space-lg);
  background: var(--surface-alt);
  border-bottom: 2px solid var(--border);
  font-size: var(--text-sm);
  color: var(--ink-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.comparison-table td {
  padding: var(--space-md) var(--space-lg);
  border-bottom: 1px solid var(--border-light);
  vertical-align: top;
}

.comparison-table tr:hover td {
  background: var(--surface-alt);
}

.risk-confirmed { color: var(--accent); font-weight: 600; }
.risk-active { color: var(--accent-warm); font-weight: 600; }
.risk-growing { color: var(--blue); font-weight: 600; }

/* --- Risk Table --- */
.risk-table {
  width: 100%;
  border-collapse: collapse;
  margin: var(--space-2xl) 0;
}

.risk-table th {
  text-align: left;
  padding: var(--space-md) var(--space-lg);
  background: var(--surface-dark);
  color: var(--surface);
  font-size: var(--text-sm);
  font-weight: 600;
}

.risk-table td {
  padding: var(--space-md) var(--space-lg);
  border-bottom: 1px solid var(--border);
  font-size: var(--text-sm);
}

.risk-table .severity-high {
  color: var(--accent);
  font-weight: 700;
}

.risk-table .severity-active {
  color: var(--accent-warm);
  font-weight: 700;
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-xl);
  border-radius: var(--radius-md);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 600;
  text-decoration: none;
  transition: all 0.2s;
  border: none;
  cursor: pointer;
  letter-spacing: 0.02em;
}

.btn:hover { text-decoration: none; }

.btn--primary {
  background: var(--accent);
  color: var(--surface);
}
.btn--primary:hover {
  background: var(--accent-dark);
  color: var(--surface);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(231, 76, 60, 0.3);
}

.btn--outline {
  background: transparent;
  color: var(--surface);
  border: 1px solid rgba(255,255,255,0.2);
}
.btn--outline:hover {
  background: rgba(255,255,255,0.05);
  border-color: rgba(255,255,255,0.4);
  color: var(--surface);
}

.btn--outline-dark {
  background: transparent;
  color: var(--ink);
  border: 1px solid var(--border);
}
.btn--outline-dark:hover {
  background: var(--surface-alt);
  border-color: var(--ink-muted);
  color: var(--ink);
}

.btn-group {
  display: flex;
  gap: var(--space-md);
  flex-wrap: wrap;
}

/* --- Timeline --- */
.timeline {
  position: relative;
  padding-left: var(--space-2xl);
}

.timeline::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--border);
}

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

.timeline__item::before {
  content: '';
  position: absolute;
  left: calc(-1 * var(--space-2xl) - 5px);
  top: 0.5em;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--surface);
}

.timeline__date {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: var(--space-xs);
}

.timeline__title {
  font-weight: 600;
  margin-bottom: var(--space-xs);
}

.timeline__desc {
  color: var(--ink-muted);
  font-size: var(--text-sm);
}

/* --- Sidebar TOC --- */
.page-layout {
  display: grid;
  grid-template-columns: 1fr 240px;
  gap: var(--space-3xl);
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-xl);
}

.page-layout__content {
  min-width: 0;
}

.toc {
  position: sticky;
  top: calc(60px + var(--space-xl));
  align-self: start;
  padding: var(--space-lg);
  border-left: 1px solid var(--border);
  max-height: calc(100vh - 100px);
  overflow-y: auto;
}

.toc__title {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--ink-muted);
  margin-bottom: var(--space-md);
}

.toc ul {
  list-style: none;
  padding: 0;
}

.toc li {
  margin-bottom: var(--space-sm);
}

.toc a {
  font-size: var(--text-sm);
  color: var(--ink-muted);
  text-decoration: none;
  display: block;
  padding: var(--space-xs) 0;
  transition: color 0.2s;
}

.toc a:hover,
.toc a.active {
  color: var(--ink);
  text-decoration: none;
}

/* --- Footer --- */
.footer {
  background: var(--surface-dark);
  color: #8899aa;
  padding: var(--space-3xl) 0;
  border-top: 1px solid rgba(255,255,255,0.06);
}

.footer__inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-xl);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-lg);
}

.footer__brand {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--surface);
  letter-spacing: 0.05em;
}

.footer__brand span { color: var(--accent); }

.footer__text {
  font-size: var(--text-sm);
}

.footer__links {
  display: flex;
  gap: var(--space-xl);
  list-style: none;
}

.footer__links a {
  color: #8899aa;
  font-size: var(--text-sm);
  text-decoration: none;
}

.footer__links a:hover {
  color: var(--surface);
  text-decoration: none;
}

/* --- Motion Template --- */
.motion-block {
  background: var(--surface-alt);
  border: 2px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-2xl);
  margin: var(--space-2xl) 0;
  font-family: var(--font-body);
}

.motion-block__title {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  margin-bottom: var(--space-lg);
  color: var(--ink);
}

.motion-block p {
  margin-bottom: var(--space-md);
}

.motion-block .motion-field {
  display: block;
  margin-top: var(--space-md);
  padding-bottom: var(--space-xs);
  border-bottom: 1px solid var(--border);
  color: var(--ink-muted);
  font-size: var(--text-sm);
}

/* --- Step Cards --- */
.steps {
  counter-reset: step;
}

.step {
  counter-increment: step;
  position: relative;
  padding-left: var(--space-3xl);
  margin-bottom: var(--space-2xl);
}

.step::before {
  content: counter(step);
  position: absolute;
  left: 0;
  top: 0;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--accent);
  color: var(--surface);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: var(--text-sm);
}

.step h4 {
  font-family: var(--font-body);
  font-weight: 700;
  font-size: var(--text-lg);
  margin-bottom: var(--space-sm);
}

.step p {
  color: var(--ink-light);
}

/* --- Page Header (sub-pages) --- */
.page-header {
  padding: calc(60px + var(--space-3xl)) 0 var(--space-3xl);
  background: var(--surface-dark);
  color: var(--surface);
}

.page-header h1 {
  font-size: var(--text-3xl);
  margin-bottom: var(--space-md);
}

.page-header p {
  font-size: var(--text-lg);
  color: #8899aa;
  max-width: 640px;
}

/* --- Responsive --- */
@media (max-width: 768px) {
  :root {
    --text-4xl: 2.25rem;
    --text-5xl: 2.75rem;
    --text-3xl: 2rem;
    --text-2xl: 1.5rem;
  }

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

  .toc {
    display: none;
  }

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

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

  .nav__links {
    display: none;
  }

  .nav__toggle {
    display: block;
  }

  .hero h1 {
    font-size: var(--text-3xl);
  }

  .footer__inner {
    flex-direction: column;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .stats-strip {
    grid-template-columns: 1fr;
  }

  .btn-group {
    flex-direction: column;
  }

  .btn { width: 100%; justify-content: center; }
}