/* ==========================================================================
   Utility Network — site styles
   Light, professional palette inspired by topographic maps and copper conduits.
   ========================================================================== */

:root {
  /* Palette */
  --color-bg: #fbf8f3;            /* warm parchment */
  --color-surface: #ffffff;
  --color-surface-2: #f4ece0;
  --color-text: #1c2a2a;          /* deep slate-teal */
  --color-muted: #5a6a6a;
  --color-primary: #0f6b6b;        /* deep teal */
  --color-primary-hover: #0a5252;
  --color-accent: #c97a3a;        /* copper */
  --color-accent-2: #5a8f5a;      /* moss green */
  --color-accent-3: #e0a96d;
  --color-link: #0f6b6b;
  --color-link-hover: #c97a3a;
  --color-border: #e2d8c5;
  --color-border-strong: #c9bba1;
  --color-code-bg: #f3ecde;
  --color-code-inline-bg: rgba(15, 107, 107, 0.07);
  --color-warn: #b86a1f;

  /* Typography */
  --font-sans: "Inter", ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, "JetBrains Mono", "SFMono-Regular", Menlo, Consolas, monospace;

  /* Type scale */
  --text-xs: 0.8125rem;
  --text-sm: 0.9375rem;
  --text-base: 1.0625rem;
  --text-lg: 1.1875rem;
  --text-xl: 1.4rem;
  --text-2xl: 1.8rem;
  --text-3xl: 2.4rem;
  --text-4xl: 3rem;

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.5rem;
  --space-6: 2rem;
  --space-7: 3rem;
  --space-8: 4.5rem;

  /* Layout */
  --radius-sm: 6px;
  --radius: 10px;
  --radius-lg: 16px;
  --shadow-sm: 0 1px 2px rgba(28, 42, 42, 0.06), 0 1px 1px rgba(28, 42, 42, 0.04);
  --shadow: 0 4px 14px rgba(28, 42, 42, 0.08), 0 1px 2px rgba(28, 42, 42, 0.05);
  --shadow-lg: 0 18px 36px -10px rgba(15, 107, 107, 0.22), 0 4px 10px rgba(28, 42, 42, 0.08);
  --transition: 180ms ease;
  --header-height: 68px;
  --container-w: min(1400px, 94vw);
  --content-w: min(1400px, 94vw);
  --prose-w: 100%;
  --measure-w: min(105ch, 100%);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: 0.001ms !important; transition-duration: 0.001ms !important; }
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.65;
  color: var(--color-text);
  background: var(--color-bg);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.container {
  width: var(--container-w);
  margin-inline: auto;
}

main.site-main {
  flex: 1 0 auto;
  padding-block: var(--space-6) var(--space-8);
}

/* Headings get a touch of color */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-text);
  letter-spacing: -0.01em;
  margin: 1.6em 0 0.6em;
  scroll-margin-top: calc(var(--header-height) + 16px);
}
h1 { font-size: var(--text-4xl); margin-top: 0.2em; }
h2 { font-size: var(--text-2xl); color: var(--color-primary); }
h3 { font-size: var(--text-xl); color: var(--color-primary-hover); }
h4 { font-size: var(--text-lg); }

p { margin: 0.8em 0 1em; }

/* Links */
a {
  color: var(--color-link);
  text-decoration: none;
  background-image: linear-gradient(currentColor, currentColor);
  background-size: 100% 1px;
  background-repeat: no-repeat;
  background-position: 0 100%;
  transition: color var(--transition), background-size var(--transition);
}
a:hover, a:focus-visible {
  color: var(--color-link-hover);
  background-size: 0% 1px;
}
a:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
  border-radius: 3px;
}

.skip-link {
  position: absolute;
  left: -1000px;
  top: 0;
  background: var(--color-primary);
  color: #fff;
  padding: 0.6rem 1rem;
  z-index: 1000;
}
.skip-link:focus { left: 0; }

/* ==========================================================================
   Header
   ========================================================================== */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(251, 248, 243, 0.92);
  backdrop-filter: saturate(140%) blur(10px);
  -webkit-backdrop-filter: saturate(140%) blur(10px);
  border-bottom: 1px solid var(--color-border);
  height: var(--header-height);
  display: flex;
  align-items: center;
}
.header-inner { position: relative; }

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-5);
  height: 100%;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  background-image: none;
  color: var(--color-text);
}
.brand:hover, .brand:focus-visible { color: var(--color-primary); background-image: none; }

.brand-mark .logo-svg { width: 40px; height: 40px; display: block; }

.brand-text { display: flex; flex-direction: column; line-height: 1.1; }
.brand-line-1 { font-weight: 800; font-size: 1.02rem; color: var(--color-primary); letter-spacing: 0.01em; }
.brand-line-2 { font-size: 0.78rem; color: var(--color-muted); }

.primary-nav ul {
  list-style: none;
  display: flex;
  gap: 0.4rem;
  padding: 0;
  margin: 0;
  align-items: center;
}
.nav-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.5rem 0.85rem;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 500;
  background-image: none;
  color: var(--color-text);
  transition: background var(--transition), color var(--transition), transform var(--transition);
}
.nav-link:hover, .nav-link:focus-visible {
  background: var(--color-surface-2);
  color: var(--color-primary-hover);
  background-image: none;
}
.nav-link.is-active {
  background: linear-gradient(135deg, rgba(15, 107, 107, 0.12), rgba(201, 122, 58, 0.12));
  color: var(--color-primary);
}
.nav-icon { width: 20px; height: 20px; flex: 0 0 auto; }

.nav-toggle {
  display: none;
  background: transparent;
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius-sm);
  padding: 0.45rem;
  cursor: pointer;
  flex-direction: column;
  gap: 4px;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
}
.nav-toggle-bar {
  width: 22px;
  height: 2px;
  background: var(--color-primary);
  border-radius: 2px;
  transition: transform var(--transition);
}

@media (max-width: 880px) {
  .nav-toggle { display: inline-flex; }
  .primary-nav {
    position: absolute;
    top: calc(var(--header-height) - 8px);
    left: 0;
    right: 0;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: 0 0 var(--radius) var(--radius);
    box-shadow: var(--shadow);
    display: none;
  }
  .primary-nav.is-open { display: block; }
  .primary-nav ul { flex-direction: column; align-items: stretch; padding: 0.6rem; gap: 0.2rem; }
  .nav-link { padding: 0.7rem 0.9rem; }
  .brand-line-2 { display: none; }
}

/* ==========================================================================
   Footer
   ========================================================================== */
.site-footer {
  flex-shrink: 0;
  background: linear-gradient(180deg, var(--color-surface-2), #ece1cc);
  border-top: 1px solid var(--color-border-strong);
  padding-block: var(--space-6);
  color: var(--color-text);
  margin-top: var(--space-7);
}
.footer-inner {
  display: grid;
  gap: var(--space-4);
  grid-template-columns: 1fr;
}
.footer-brand { display: inline-flex; align-items: center; gap: 0.7rem; }
.footer-logo .logo-svg { width: 36px; height: 36px; }
.footer-title { font-weight: 700; color: var(--color-primary); }
.footer-nav ul { list-style: none; display: flex; flex-wrap: wrap; gap: 0.9rem 1.4rem; padding: 0; margin: 0; }
.footer-nav a { color: var(--color-text); font-weight: 500; }
.footer-meta { font-size: var(--text-sm); color: var(--color-muted); margin: 0; }
@media (min-width: 720px) {
  .footer-inner { grid-template-columns: auto 1fr auto; align-items: center; }
}

/* ==========================================================================
   Hero / Front page
   ========================================================================== */
.hero-wrap {
  /* Full-bleed background, content stays in container */
  background:
    radial-gradient(ellipse at 25% 0%, rgba(15, 107, 107, 0.10), transparent 55%),
    radial-gradient(ellipse at 80% 25%, rgba(201, 122, 58, 0.12), transparent 60%),
    radial-gradient(ellipse at 50% 100%, rgba(90, 143, 90, 0.08), transparent 55%);
  border-bottom: 1px solid var(--color-border);
  margin-block: calc(var(--space-6) * -1) var(--space-7);
}
.hero {
  text-align: center;
  padding: var(--space-7) 0 var(--space-7);
}
.hero-logo {
  display: block;
  margin: 0 auto var(--space-5);
}
.hero-logo svg {
  width: clamp(140px, 22vw, 240px);
  height: auto;
  filter: drop-shadow(0 10px 20px rgba(15, 107, 107, 0.16));
}
.hero-title {
  font-size: clamp(1.6rem, 4.6vw, 3.6rem);
  margin: 0;
  background: linear-gradient(120deg, #0f6b6b 0%, #1d8a8a 35%, #c97a3a 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  overflow-wrap: break-word;
  word-wrap: break-word;
  hyphens: auto;
  padding: 0 0.2em;
}
.hero-tagline {
  max-width: 95ch;
  margin: var(--space-4) auto;
  font-size: var(--text-lg);
  color: var(--color-muted);
}
.hero-paragraphs {
  max-width: 95ch;
  margin: 0 auto var(--space-5);
  text-align: left;
}
.hero-paragraphs p { font-size: var(--text-base); }

.cta-row {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-3);
  margin-top: var(--space-5);
}
.cta-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius);
  padding: 0.85rem 1.2rem;
  font-weight: 600;
  color: var(--color-text);
  box-shadow: var(--shadow-sm);
  background-image: none;
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition), color var(--transition);
}
.cta-btn .icon { width: 26px; height: 26px; flex: 0 0 auto; }
.cta-btn:hover, .cta-btn:focus-visible {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary);
  color: var(--color-primary-hover);
  background-image: none;
}

/* Section cards on the home page */
.section-cards {
  display: grid;
  gap: var(--space-4);
  margin-top: var(--space-7);
  grid-template-columns: 1fr;
}
@media (min-width: 720px) {
  .section-cards { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 1100px) {
  .section-cards { grid-template-columns: repeat(3, 1fr); }
}
.section-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-5);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  background-image: none;
  color: var(--color-text);
}
.section-card:hover, .section-card:focus-visible {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary);
  background-image: none;
}
.section-card .icon { width: 36px; height: 36px; }
.section-card h3 { margin: 0; color: var(--color-primary); }
.section-card p { margin: 0; color: var(--color-muted); }
.section-card .card-cta {
  margin-top: auto;
  font-weight: 600;
  color: var(--color-accent);
}

.home-intro {
  margin: var(--space-7) auto;
  max-width: 76ch;
}
.home-intro h2 { text-align: center; }

/* ==========================================================================
   Content pages
   ========================================================================== */
.content-page { padding-block: var(--space-4); }

.content-page .content-shell {
  width: var(--content-w);
  margin-inline: auto;
}

.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 0.5rem;
  font-size: var(--text-sm);
  color: var(--color-muted);
  margin-bottom: var(--space-3);
}
.breadcrumbs ol { list-style: none; padding: 0; margin: 0; display: contents; }
.breadcrumbs li { display: inline-flex; align-items: center; gap: 0.4rem; }
.breadcrumbs li + li::before {
  content: "›";
  color: var(--color-muted);
  margin-right: 0.2rem;
}
.breadcrumbs a { color: var(--color-muted); font-weight: 500; }
.breadcrumbs a:hover { color: var(--color-primary); }
.breadcrumbs .crumb-current { color: var(--color-text); font-weight: 600; }

.content-page h1 {
  background: linear-gradient(110deg, #0f6b6b 0%, #c97a3a 90%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  overflow-wrap: break-word;
  hyphens: auto;
}
.prose .header-anchor,
.prose .header-anchor:hover {
  background-image: none;
  color: inherit;
  text-decoration: none;
}
.prose .header-anchor:hover { color: var(--color-link-hover); }
.prose h1 .header-anchor,
.prose h2 .header-anchor,
.prose h3 .header-anchor,
.prose h4 .header-anchor { color: inherit; }

.prose {
  /* Use the full content container width on desktop. */
  font-size: var(--text-base);
  max-width: 100%;
}
.prose > *,
.prose > p,
.prose > ul,
.prose > ol,
.prose > blockquote,
.prose > h1, .prose > h2, .prose > h3, .prose > h4,
.prose > .code-block,
.prose > .table-scroll,
.prose > .mermaid,
.prose > .faq-accordion,
.prose > .related { max-width: 100%; }
.prose ul, .prose ol { padding-left: 1.4em; }
.prose li { margin: 0.25em 0; }
.prose blockquote {
  border-left: 4px solid var(--color-accent);
  background: var(--color-surface-2);
  padding: var(--space-3) var(--space-4);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: var(--space-4) 0;
  color: var(--color-text);
}
.prose hr {
  border: none;
  border-top: 1px solid var(--color-border-strong);
  margin: var(--space-6) 0;
}

/* Inline code */
.prose :not(pre) > code {
  font-family: var(--font-mono);
  font-size: 0.92em;
  background: var(--color-code-inline-bg);
  color: var(--color-primary-hover);
  padding: 0.08em 0.42em;
  border-radius: 4px;
  border: none;
}

/* Code blocks */
.code-block {
  position: relative;
  margin: var(--space-4) 0;
}
.code-block pre {
  background: var(--color-code-bg);
  color: var(--color-text);
  border-radius: var(--radius);
  padding: var(--space-4);
  padding-right: 4.5rem; /* room for copy btn */
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.92rem;
  line-height: 1.55;
  border: 1px solid var(--color-border);
}
.code-block pre code { background: transparent; padding: 0; color: inherit; }
.copy-btn {
  position: absolute;
  top: 0.6rem;
  right: 0.6rem;
  background: var(--color-surface);
  color: var(--color-primary);
  border: 1px solid var(--color-border-strong);
  padding: 0.3rem 0.65rem;
  font: 600 0.78rem var(--font-sans);
  border-radius: var(--radius-sm);
  cursor: pointer;
  opacity: 0.85;
  transition: opacity var(--transition), background var(--transition), color var(--transition), transform var(--transition);
}
.copy-btn:hover { opacity: 1; background: var(--color-primary); color: #fff; transform: translateY(-1px); }
.copy-btn.is-copied { background: var(--color-accent-2); color: #fff; border-color: var(--color-accent-2); }

/* Tables */
.table-scroll {
  overflow-x: auto;
  margin: var(--space-4) 0;
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
}
.table-scroll table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--text-sm);
}
.table-scroll th, .table-scroll td {
  text-align: left;
  padding: 0.7rem 0.95rem;
  border-bottom: 1px solid var(--color-border);
}
.table-scroll th {
  background: var(--color-surface-2);
  color: var(--color-primary);
  font-weight: 700;
}
.table-scroll tbody tr:nth-child(even) { background: rgba(244, 236, 224, 0.5); }
.table-scroll tbody tr:hover { background: rgba(15, 107, 107, 0.06); }

/* Task lists / checkboxes */
.task-list-item {
  list-style: none;
  position: relative;
  padding-left: 0;
}
.contains-task-list { padding-left: 0.2em; }
.task-list-item input[type="checkbox"] {
  appearance: none;
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  border: 2px solid var(--color-border-strong);
  border-radius: 4px;
  margin-right: 0.55rem;
  cursor: pointer;
  vertical-align: -3px;
  position: relative;
  transition: background var(--transition), border-color var(--transition);
}
.task-list-item input[type="checkbox"]:checked {
  background: var(--color-primary);
  border-color: var(--color-primary);
}
.task-list-item input[type="checkbox"]:checked::after {
  content: "";
  position: absolute;
  left: 4px;
  top: 0px;
  width: 5px;
  height: 10px;
  border: solid #fff;
  border-width: 0 2px 2px 0;
  transform: rotate(45deg);
}
.task-list-item.task-done { color: var(--color-muted); }
.task-list-item.task-done > * { text-decoration: line-through; }
.task-list-item.task-done > input[type="checkbox"] { text-decoration: none; }

/* FAQ accordions */
.faq-accordion { display: flex; flex-direction: column; gap: var(--space-2); margin: var(--space-3) 0 var(--space-5); }
.faq-item {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 0.2rem 0;
  transition: border-color var(--transition), box-shadow var(--transition);
}
.faq-item[open] { border-color: var(--color-primary); box-shadow: var(--shadow-sm); }
.faq-item > summary {
  list-style: none;
  cursor: pointer;
  padding: 0.85rem 1.1rem;
  font-weight: 600;
  color: var(--color-primary);
  display: flex;
  align-items: center;
  gap: 0.6rem;
}
.faq-item > summary::-webkit-details-marker { display: none; }
.faq-item > summary::before {
  content: "+";
  font-size: 1.2rem;
  color: var(--color-accent);
  width: 1rem;
  flex: 0 0 auto;
  transition: transform var(--transition);
}
.faq-item[open] > summary::before { content: "−"; }
.faq-body { padding: 0 1.1rem 0.9rem; }
.faq-body p:first-child { margin-top: 0; }

/* ==========================================================================
   Reading enhancements (auto-inserted by build transform)
   ========================================================================== */

/* Top reading-progress bar */
.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  width: 0;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  z-index: 200;
  transition: width 80ms linear;
  pointer-events: none;
}

/* Article meta strip: reading time + word count */
.article-meta {
  display: inline-flex;
  flex-wrap: wrap;
  gap: 1rem;
  align-items: center;
  margin: 0 0 var(--space-4);
  padding: 0.45rem 0.9rem;
  font-size: var(--text-sm);
  color: var(--color-muted);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 999px;
}
.article-meta .meta-time {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: var(--color-primary);
  font-weight: 600;
}
.article-meta .meta-words::before {
  content: "·";
  margin-right: 0.6rem;
  color: var(--color-border-strong);
}

/* On-this-page TOC */
.toc {
  margin: 0 0 var(--space-5);
  border: 1px solid var(--color-border);
  border-left: 4px solid var(--color-accent);
  border-radius: var(--radius);
  background: linear-gradient(180deg, var(--color-surface), var(--color-surface-2));
  padding: 0;
  overflow: hidden;
}
.toc details > summary {
  list-style: none;
  cursor: pointer;
  padding: 0.7rem 1rem;
  font-weight: 700;
  color: var(--color-primary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
  user-select: none;
}
.toc details > summary::-webkit-details-marker { display: none; }
.toc details > summary::before {
  content: "▸";
  font-size: 0.85rem;
  color: var(--color-accent);
  transition: transform var(--transition);
}
.toc details[open] > summary::before { transform: rotate(90deg); }
.toc ol {
  margin: 0;
  padding: 0 1rem 0.85rem 2.4rem;
  counter-reset: toc;
}
.toc li {
  list-style: none;
  counter-increment: toc;
  position: relative;
  padding: 0.18rem 0;
  font-size: var(--text-sm);
}
.toc li::before {
  content: counter(toc, decimal-leading-zero);
  position: absolute;
  left: -1.7rem;
  top: 0.2rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--color-accent);
  font-weight: 700;
}
.toc a {
  color: var(--color-text);
  background-image: none;
  transition: color var(--transition);
}
.toc a:hover, .toc a:focus-visible {
  color: var(--color-primary);
  background-image: none;
}

@media (min-width: 1280px) {
  /* Two-column grid: prose on the left, sticky TOC on the right. */
  .content-page .content-shell {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 280px;
    grid-template-areas:
      "bc       bc"
      "meta     meta"
      "main     aside"
      "related  related";
    column-gap: var(--space-6);
    row-gap: 0;
  }
  .content-page .breadcrumbs { grid-area: bc; }
  .content-page .article-meta { grid-area: meta; }
  .content-page .prose { grid-area: main; min-width: 0; }
  .content-page .related { grid-area: related; }
  .content-page .toc {
    grid-area: aside;
    align-self: start;
    position: sticky;
    top: calc(var(--header-height) + 12px);
    margin: 0;
  }
}

/* Lede: first paragraph of a content article */
.prose .lede {
  font-size: clamp(1.05rem, 1vw + 0.95rem, 1.22rem);
  line-height: 1.55;
  color: var(--color-text);
  border-left: 3px solid var(--color-accent);
  padding-left: 1rem;
  margin-top: var(--space-4);
  font-weight: 450;
}

/* Step-number badges on H2 headings */
h2 .step-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2rem;
  height: 2rem;
  margin-right: 0.7rem;
  vertical-align: -0.3rem;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  font-weight: 700;
  color: #fff;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  border-radius: 999px;
  box-shadow: 0 4px 10px -3px rgba(15, 107, 107, 0.35);
  flex: 0 0 auto;
}

/* Mermaid */
.mermaid {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-4);
  margin: var(--space-4) 0;
  overflow-x: auto;
  text-align: center;
}

/* Related pages */
.related {
  margin-top: var(--space-7);
  padding-top: var(--space-5);
  border-top: 1px solid var(--color-border);
}
.related h2 { font-size: var(--text-xl); margin-top: 0; }
.related ul {
  list-style: none;
  padding: 0;
  display: grid;
  gap: var(--space-3);
  grid-template-columns: 1fr;
}
@media (min-width: 800px) { .related ul { grid-template-columns: repeat(2, 1fr); } }
.related a {
  display: block;
  padding: var(--space-3) var(--space-4);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background-image: none;
  transition: transform var(--transition), border-color var(--transition), box-shadow var(--transition);
}
.related a:hover, .related a:focus-visible {
  transform: translateY(-2px);
  border-color: var(--color-primary);
  box-shadow: var(--shadow);
  background-image: none;
}
.related a strong { display: block; color: var(--color-primary); margin-bottom: 0.1rem; }
.related a span { color: var(--color-muted); font-size: var(--text-sm); }

/* Section index — child page list */
.child-list {
  display: grid;
  gap: var(--space-4);
  grid-template-columns: 1fr;
  margin: var(--space-5) 0;
}
@media (min-width: 720px) { .child-list { grid-template-columns: repeat(2, 1fr); } }

/* Utility */
.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0,0,0,0);
  white-space: nowrap; border: 0;
}

/* KaTeX integration tweaks */
.katex-display { overflow-x: auto; overflow-y: hidden; padding: 0.2rem 0; }

/* Print */
@media print {
  .site-header, .site-footer, .copy-btn, .nav-toggle { display: none !important; }
  a { color: var(--color-text); }
  .code-block pre { white-space: pre-wrap; word-break: break-word; }
}