/* =========================================================================
   SQLite Production Hardening & WAL Optimization
   Light, elegant, professional theme. Mobile-first, widescreen-aware.
   ========================================================================= */

/* ---- Design tokens ---------------------------------------------------- */
:root {
  /* Brand palette */
  --c-blue: #2563eb;
  --c-blue-700: #1d4ed8;
  --c-sky: #0ea5e9;
  --c-teal: #14b8a6;
  --c-teal-700: #0f9488;
  --c-amber: #f59e0b;

  /* Neutrals */
  --bg: #f6f8fc;
  --bg-soft: #eef3fa;
  --surface: #ffffff;
  --surface-2: #f9fbfe;
  --ink: #1e293b;
  --ink-soft: #334155;
  --muted: #64748b;
  --border: #e2e8f0;
  --border-strong: #cbd5e1;

  /* Code */
  --code-bg: #f4f7fc;
  --code-inline-bg: #eef2fb;
  --code-ink: #334155;

  /* Accents derived */
  --link: var(--c-blue);
  --link-hover: var(--c-blue-700);

  /* Shape & depth */
  --radius: 14px;
  --radius-sm: 10px;
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.06), 0 1px 3px rgba(15, 23, 42, 0.05);
  --shadow-md: 0 6px 20px rgba(15, 23, 42, 0.08);
  --shadow-lg: 0 18px 48px rgba(30, 64, 175, 0.14);

  /* Layout */
  --header-h: 66px;
  --wrap: 1180px;
  --wrap-wide: 1320px;
  --gradient: linear-gradient(100deg, var(--c-blue), var(--c-sky) 55%, var(--c-teal));

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

/* ---- Reset / base ----------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 16px); /* in-page links clear sticky header */
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  font-family: var(--font-sans);
  font-size: 1.0625rem;
  line-height: 1.7;
  color: var(--ink);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.site-main { flex: 1 0 auto; }

img, svg { max-width: 100%; }
img { height: auto; }

.wrap {
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: clamp(1rem, 4vw, 2.5rem);
}

/* ---- Links ------------------------------------------------------------ */
a { color: var(--link); text-decoration: none; transition: color .18s ease; }
a:hover { color: var(--link-hover); }

.prose a:not(.card):not(.header-anchor) {
  color: var(--link);
  text-decoration: underline;
  text-decoration-color: color-mix(in srgb, var(--c-sky) 45%, transparent);
  text-underline-offset: 3px;
  text-decoration-thickness: 1.5px;
  transition: color .18s ease, text-decoration-color .18s ease, background-color .18s ease;
  border-radius: 3px;
}
.prose a:not(.card):not(.header-anchor):hover {
  color: var(--c-teal-700);
  text-decoration-color: var(--c-teal);
  background: color-mix(in srgb, var(--c-teal) 9%, transparent);
}

:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--c-sky) 60%, transparent);
  outline-offset: 2px;
  border-radius: 4px;
}

.skip-link {
  position: fixed;
  top: -100px; left: 12px;
  z-index: 1000;
  background: var(--surface);
  color: var(--ink);
  padding: .6rem 1rem;
  border-radius: 8px;
  box-shadow: var(--shadow-md);
  transition: top .2s ease;
}
.skip-link:focus { top: 12px; }

.ico { width: 1.15em; height: 1.15em; flex: none; }

/* =========================================================================
   Header
   ========================================================================= */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: color-mix(in srgb, var(--surface) 86%, transparent);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  display: flex;
  align-items: center;
  gap: 1rem;
  min-height: var(--header-h);
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: .7rem;
  color: var(--ink);
  font-weight: 700;
  margin-right: auto;
}
.brand-logo { border-radius: 10px; box-shadow: var(--shadow-sm); transition: transform .2s ease; }
.brand:hover .brand-logo { transform: rotate(-4deg) scale(1.05); }
.brand-text { display: flex; flex-direction: column; line-height: 1.15; }
.brand-title { font-size: 1.02rem; letter-spacing: -0.01em; }
.brand-sub { font-size: .78rem; color: var(--muted); font-weight: 600; }

.primary-nav { display: flex; align-items: center; gap: .4rem; }
.nav-link {
  display: inline-flex;
  align-items: center;
  gap: .45rem;
  padding: .5rem .85rem;
  border-radius: 999px;
  color: var(--ink-soft);
  font-weight: 600;
  font-size: .96rem;
  border: 1px solid transparent;
  transition: background-color .18s ease, color .18s ease, border-color .18s ease, transform .12s ease;
}
.nav-link:hover { background: var(--bg-soft); color: var(--c-blue); transform: translateY(-1px); }
.nav-link.is-active {
  color: var(--c-blue-700);
  background: color-mix(in srgb, var(--c-blue) 10%, transparent);
  border-color: color-mix(in srgb, var(--c-blue) 22%, transparent);
}
.nav-link .ico { color: var(--c-sky); }
.nav-link.is-active .ico { color: var(--c-blue); }

.nav-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 42px; height: 42px;
  border: 1px solid var(--border);
  background: var(--surface);
  border-radius: 10px;
  color: var(--ink);
  cursor: pointer;
}
.nav-toggle:hover { background: var(--bg-soft); }

/* =========================================================================
   Hero (home)
   ========================================================================= */
.hero {
  background:
    radial-gradient(1200px 480px at 15% -10%, color-mix(in srgb, var(--c-sky) 16%, transparent), transparent 60%),
    radial-gradient(1000px 460px at 100% 0%, color-mix(in srgb, var(--c-teal) 14%, transparent), transparent 55%),
    var(--bg);
  border-bottom: 1px solid var(--border);
}
.hero-inner {
  text-align: center;
  padding-block: clamp(2.5rem, 6vw, 5rem);
}
.hero-logo {
  width: clamp(96px, 16vw, 160px);
  height: auto;
  border-radius: 26px;
  box-shadow: var(--shadow-lg);
  display: block;
  margin: 0 auto 1.6rem; /* logo on its own line */
  transition: transform .3s ease;
}
.hero-logo:hover { transform: translateY(-4px) scale(1.03); }
.hero-title {
  margin: 0 0 1rem;
  font-size: clamp(2rem, 5.2vw, 3.4rem);
  line-height: 1.08;
  letter-spacing: -0.025em;
  font-weight: 800;
}
.grad, .grad-title {
  background: var(--gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hero-lede {
  max-width: 60ch;
  margin: 0 auto 2rem;
  font-size: clamp(1.05rem, 2.2vw, 1.3rem);
  color: var(--ink-soft);
}
.hero-cta {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1rem;
  max-width: 820px;
  margin: 0 auto;
}
.cta {
  display: flex;
  align-items: center;
  gap: .9rem;
  text-align: left;
  padding: 1rem 1.1rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  color: var(--ink);
  transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease;
}
.cta:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); border-color: var(--border-strong); color: var(--ink); }
.cta-ico {
  display: grid; place-items: center;
  width: 48px; height: 48px; flex: none;
  border-radius: 12px;
  color: #fff;
}
.cta-ico .ico { width: 1.5em; height: 1.5em; }
.cta-shield .cta-ico { background: linear-gradient(135deg, var(--c-blue), var(--c-sky)); }
.cta-bolt .cta-ico { background: linear-gradient(135deg, var(--c-teal), var(--c-sky)); }
.cta-text { display: flex; flex-direction: column; }
.cta-label { font-weight: 700; }
.cta-sub { font-size: .85rem; color: var(--muted); }
.cta-go { margin-left: auto; color: var(--muted); transition: transform .18s ease, color .18s ease; }
.cta:hover .cta-go { transform: translateX(4px); color: var(--c-blue); }

/* =========================================================================
   Home body
   ========================================================================= */
.home-body { padding-block: clamp(2.5rem, 5vw, 4rem); display: grid; gap: clamp(2.5rem, 5vw, 4rem); }
.section-h {
  font-size: clamp(1.4rem, 3vw, 1.9rem);
  letter-spacing: -0.02em;
  margin: 0 0 1.2rem;
  font-weight: 800;
}
.intro p { color: var(--ink-soft); }
.intro-audience { color: var(--ink); }

.card-grid { list-style: none; margin: 0; padding: 0; display: grid; gap: 1rem; }
.card-grid.wide { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }

.feature-card {
  display: flex;
  flex-direction: column;
  gap: .6rem;
  padding: 1.5rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-top: 4px solid var(--accent, var(--c-blue));
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  color: var(--ink);
  transition: transform .18s ease, box-shadow .18s ease;
}
.feature-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); color: var(--ink); }
.feature-ico {
  display: grid; place-items: center;
  width: 52px; height: 52px;
  border-radius: 14px;
  color: #fff;
  background: var(--accent, var(--c-blue));
}
.feature-ico .ico { width: 1.6em; height: 1.6em; }
.feature-title { font-size: 1.2rem; font-weight: 700; letter-spacing: -0.01em; }
.feature-blurb { color: var(--muted); font-size: .98rem; }
.feature-more {
  margin-top: auto;
  display: inline-flex; align-items: center; gap: .4rem;
  color: var(--accent, var(--c-blue));
  font-weight: 600;
}
.feature-card:hover .feature-more .ico { transform: translateX(4px); }
.feature-more .ico { transition: transform .18s ease; }

.topic-list { list-style: none; margin: 0; padding: 0; display: grid; gap: .9rem; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.topic-list li {
  display: flex; align-items: flex-start; gap: .8rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 1rem 1.1rem;
  box-shadow: var(--shadow-sm);
}
.topic-list .ico { color: var(--c-teal); width: 1.4em; height: 1.4em; margin-top: .15rem; }
.topic-list code { background: var(--code-inline-bg); }

/* =========================================================================
   Page shell (content & content-index)
   ========================================================================= */
.page-shell { padding-block: clamp(1.5rem, 3vw, 2.5rem) clamp(2.5rem, 5vw, 4rem); }

/* Breadcrumbs */
.breadcrumbs { margin-bottom: 1.4rem; font-size: .9rem; }
.breadcrumbs ol {
  list-style: none; margin: 0; padding: 0;
  display: flex; flex-wrap: wrap; align-items: center; gap: .25rem;
  color: var(--muted);
}
.breadcrumbs li { display: inline-flex; align-items: center; }
.breadcrumbs li + li::before { content: "/"; margin: 0 .5rem; color: var(--border-strong); }
.breadcrumbs a { color: var(--muted); font-weight: 600; }
.breadcrumbs a:hover { color: var(--c-blue); }
.breadcrumbs [aria-current="page"] span { color: var(--ink); font-weight: 700; }

/* =========================================================================
   Prose (rendered markdown)
   ========================================================================= */
/* Prose fills the full width of its container (the .wrap), rather than being
   pinned to a narrow reading column. The container itself keeps it off the
   page edges and responsive on mobile. */
.prose { max-width: 100%; }
.prose > * { max-width: 100%; }

.prose h1 {
  font-size: clamp(1.9rem, 4.4vw, 2.9rem);
  line-height: 1.12;
  letter-spacing: -0.025em;
  font-weight: 800;
  margin: 0 0 1.2rem;
  background: var(--gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.prose h2 {
  font-size: clamp(1.4rem, 3vw, 1.85rem);
  letter-spacing: -0.02em;
  font-weight: 750;
  margin: 2.4rem 0 1rem;
  padding-bottom: .4rem;
  border-bottom: 2px solid var(--border);
  color: var(--ink);
}
.prose h3 {
  font-size: clamp(1.15rem, 2.4vw, 1.4rem);
  font-weight: 700;
  margin: 1.9rem 0 .7rem;
  color: var(--c-blue-700);
}
.prose h4 { font-size: 1.1rem; font-weight: 700; margin: 1.5rem 0 .5rem; color: var(--ink-soft); }
.prose p { margin: 0 0 1.1rem; color: var(--ink-soft); }
.prose strong { color: var(--ink); font-weight: 700; }

.prose ul, .prose ol { margin: 0 0 1.2rem; padding-left: 1.4rem; color: var(--ink-soft); }
.prose li { margin: .35rem 0; }
.prose li::marker { color: var(--c-sky); }

.prose blockquote {
  margin: 1.4rem 0;
  padding: .6rem 1.2rem;
  border-left: 4px solid var(--c-teal);
  background: var(--surface-2);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--ink-soft);
}

/* Header anchors (appear on hover) */
.header-anchor {
  margin-left: .4rem;
  color: var(--border-strong);
  text-decoration: none;
  opacity: 0;
  transition: opacity .15s ease, color .15s ease;
  font-weight: 500;
}
.prose h2:hover .header-anchor,
.prose h3:hover .header-anchor,
.prose h4:hover .header-anchor { opacity: 1; }
.header-anchor:hover { color: var(--c-blue); }

/* Anchor scroll offset on headings too */
.prose :is(h1, h2, h3, h4)[id] { scroll-margin-top: calc(var(--header-h) + 16px); }

/* ---- Inline code ------------------------------------------------------ */
.prose :not(pre) > code {
  font-family: var(--font-mono);
  font-size: .9em;
  background: var(--code-inline-bg);
  color: var(--code-ink);
  padding: .12em .4em;
  border-radius: 6px;
  border: 0;
  white-space: break-spaces;
}

/* ---- Code blocks ------------------------------------------------------ */
.prose pre,
.prose pre[class*="language-"] {
  position: relative;
  margin: 1.4rem 0;
  padding: 1.1rem 1.2rem;
  background: var(--code-bg);
  color: var(--code-ink);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: auto;
  font-size: .9rem;
  line-height: 1.6;
  box-shadow: var(--shadow-sm);
  -moz-tab-size: 2; tab-size: 2;
}
.prose pre code { font-family: var(--font-mono); background: none; padding: 0; border: 0; font-size: inherit; color: inherit; }

/* Copy button */
.code-block { position: relative; }
.copy-btn {
  position: absolute;
  top: .55rem; right: .55rem;
  display: inline-flex; align-items: center; gap: .35rem;
  padding: .32rem .55rem;
  font: 600 .78rem/1 var(--font-sans);
  color: var(--muted);
  background: color-mix(in srgb, var(--surface) 88%, transparent);
  border: 1px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
  opacity: 0;
  transition: opacity .15s ease, color .15s ease, border-color .15s ease, background-color .15s ease;
}
.code-block:hover .copy-btn,
.copy-btn:focus-visible { opacity: 1; }
.copy-btn:hover { color: var(--c-blue); border-color: color-mix(in srgb, var(--c-blue) 35%, var(--border)); }
.copy-btn .ico { width: 1em; height: 1em; }
.copy-btn.copied { color: var(--c-teal-700); border-color: var(--c-teal); }

/* ---- PrismJS light token theme (matches site colors) ------------------ */
.token.comment, .token.prolog, .token.doctype, .token.cdata { color: #8a97a8; font-style: italic; }
.token.punctuation { color: #5b6b7b; }
.token.property, .token.tag, .token.boolean, .token.number, .token.constant,
.token.symbol, .token.deleted { color: #b4317f; }
.token.selector, .token.attr-name, .token.string, .token.char, .token.builtin, .token.inserted { color: var(--c-teal-700); }
.token.operator, .token.entity, .token.url, .language-css .token.string, .style .token.string { color: #0e7490; }
.token.atrule, .token.attr-value, .token.keyword { color: var(--c-blue); }
.token.function, .token.class-name { color: #7c3aed; }
.token.regex, .token.important, .token.variable { color: var(--c-amber); }
.token.important, .token.bold { font-weight: 700; }
.token.italic { font-style: italic; }

/* ---- Tables ----------------------------------------------------------- */
.table-wrap {
  margin: 1.4rem 0;
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-sm);
  -webkit-overflow-scrolling: touch;
}
.prose table { width: 100%; border-collapse: collapse; font-size: .95rem; min-width: 520px; }
.prose thead th {
  background: var(--bg-soft);
  color: var(--ink);
  text-align: left;
  font-weight: 700;
  padding: .8rem 1rem;
  border-bottom: 2px solid var(--border-strong);
  white-space: nowrap;
}
.prose tbody td { padding: .75rem 1rem; border-bottom: 1px solid var(--border); vertical-align: top; color: var(--ink-soft); }
.prose tbody tr:nth-child(odd) { background: var(--surface-2); }
.prose tbody tr:hover { background: color-mix(in srgb, var(--c-sky) 7%, transparent); }
.prose tbody tr:last-child td { border-bottom: 0; }
.prose td code, .prose th code { background: var(--code-inline-bg); white-space: nowrap; }

/* ---- Task lists (togglable checkboxes) -------------------------------- */
.prose .contains-task-list { list-style: none; padding-left: .2rem; }
.prose .task-list-item { display: flex; align-items: flex-start; gap: .6rem; margin: .5rem 0; }
.prose .task-list-item::marker { content: ""; }   /* remove the dot */
.prose .task-list-item-checkbox {
  appearance: none; -webkit-appearance: none;
  width: 1.2em; height: 1.2em; flex: none;
  margin-top: .22em;
  border: 2px solid var(--border-strong);
  border-radius: 6px;
  background: var(--surface);
  cursor: pointer;
  position: relative;
  transition: background-color .15s ease, border-color .15s ease;
}
.prose .task-list-item-checkbox:hover { border-color: var(--c-blue); }
.prose .task-list-item-checkbox:checked { background: var(--c-blue); border-color: var(--c-blue); }
.prose .task-list-item-checkbox:checked::after {
  content: "";
  position: absolute;
  left: 50%; top: 46%;
  width: .3em; height: .58em;
  border: solid #fff;
  border-width: 0 2.5px 2.5px 0;
  transform: translate(-50%, -55%) rotate(45deg);
}
.prose .task-list-item.is-checked label,
.prose .task-list-item.is-checked { color: var(--muted); text-decoration: line-through; }
.prose .task-list-item label { cursor: pointer; }

/* ---- FAQ accordion (for any <details> / FAQ content) ------------------ */
.prose details {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  margin: .8rem 0;
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}
.prose details summary {
  cursor: pointer;
  list-style: none;
  padding: 1rem 1.2rem;
  font-weight: 700;
  color: var(--ink);
  display: flex; align-items: center; gap: .6rem;
}
.prose details summary::-webkit-details-marker { display: none; }
.prose details summary::before {
  content: "";
  width: .55em; height: .55em; flex: none;
  border-right: 2.5px solid var(--c-sky);
  border-bottom: 2.5px solid var(--c-sky);
  transform: rotate(-45deg);
  transition: transform .2s ease;
}
.prose details[open] summary::before { transform: rotate(45deg); }
.prose details > :not(summary) { padding: 0 1.2rem 1rem; margin: 0; }

/* ---- Mermaid diagrams + figures --------------------------------------- */
.mermaid { margin: 1.4rem 0; text-align: center; }
.mermaid svg { max-width: 100%; height: auto; }

/* Pre-render: the raw fenced source while mermaid loads. */
.prose pre code.language-mermaid { color: var(--muted); }

.diagram {
  margin: 1.8rem 0;
  padding: 1.2rem 1rem .6rem;
  background:
    radial-gradient(120% 80% at 50% 0%, color-mix(in srgb, var(--c-sky) 7%, transparent), transparent 70%),
    var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  position: relative;
}
.diagram .mermaid { margin: .2rem 0 0; cursor: zoom-in; transition: transform .18s ease; }
.diagram .mermaid:focus-visible { outline: 3px solid color-mix(in srgb, var(--c-sky) 60%, transparent); outline-offset: 6px; border-radius: 8px; }
.diagram__expand {
  position: absolute;
  top: .7rem; right: .7rem;
  display: inline-flex; align-items: center; gap: .35rem;
  padding: .35rem .6rem;
  font: 600 .8rem/1 var(--font-sans);
  color: var(--muted);
  background: color-mix(in srgb, var(--surface) 88%, transparent);
  border: 1px solid var(--border);
  border-radius: 999px;
  cursor: pointer;
  opacity: 0;
  transition: opacity .15s ease, color .15s ease, border-color .15s ease, transform .12s ease;
}
.diagram:hover .diagram__expand,
.diagram:focus-within .diagram__expand { opacity: 1; }
.diagram__expand:hover { color: var(--c-blue); border-color: color-mix(in srgb, var(--c-blue) 35%, var(--border)); transform: translateY(-1px); }
.diagram__expand .ico { width: 1em; height: 1em; }
.diagram__caption {
  margin: .6rem .2rem 0;
  text-align: center;
  font-size: .9rem;
  color: var(--muted);
  font-style: italic;
}

/* Fullscreen lightbox */
body.modal-open { overflow: hidden; }
.diagram-modal { position: fixed; inset: 0; z-index: 1000; display: grid; place-items: center; }
.diagram-modal[hidden] { display: none; }
.diagram-modal__backdrop {
  position: absolute; inset: 0;
  background: color-mix(in srgb, #0f172a 78%, transparent);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  animation: modal-fade .18s ease;
}
.diagram-modal__panel {
  position: relative;
  z-index: 1;
  width: min(96vw, 1500px);
  max-height: 94vh;
  display: flex;
  flex-direction: column;
  gap: .6rem;
  padding: clamp(1rem, 3vw, 2rem);
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  animation: modal-pop .2s ease;
}
.diagram-modal__close {
  position: absolute;
  top: .7rem; right: .7rem;
  display: inline-flex; align-items: center; justify-content: center;
  width: 40px; height: 40px;
  border: 1px solid var(--border);
  background: var(--surface);
  border-radius: 10px;
  color: var(--ink);
  cursor: pointer;
  transition: background-color .15s ease, color .15s ease, border-color .15s ease;
}
.diagram-modal__close:hover { background: var(--bg-soft); color: var(--c-blue); border-color: var(--border-strong); }
.diagram-modal__stage {
  flex: 1 1 auto;
  min-height: 0;
  overflow: auto;
  display: grid;
  place-items: center;
}
.diagram-modal__stage svg {
  width: auto;
  height: auto;
  max-width: 100% !important;
  max-height: 84vh;
}
.diagram-modal__caption {
  margin: 0;
  text-align: center;
  color: var(--muted);
  font-size: .95rem;
  font-style: italic;
}
@keyframes modal-fade { from { opacity: 0; } to { opacity: 1; } }
@keyframes modal-pop { from { opacity: 0; transform: translateY(8px) scale(.98); } to { opacity: 1; transform: none; } }

/* ---- KaTeX overflow --------------------------------------------------- */
.katex-display { overflow-x: auto; overflow-y: hidden; padding: .3rem 0; }

/* =========================================================================
   Subpages / related cards & prev-next (content pages)
   ========================================================================= */
.subpages { margin-top: 3rem; padding-top: 2rem; border-top: 1px solid var(--border); }
.subpages-title { display: flex; align-items: center; gap: .5rem; font-size: 1.25rem; font-weight: 750; margin: 0 0 1.1rem; }
.subpages-title .ico { color: var(--c-teal); }

.card {
  display: flex; align-items: center; justify-content: space-between; gap: 1rem;
  padding: 1rem 1.2rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-sm);
  color: var(--ink);
  transition: transform .16s ease, box-shadow .16s ease, border-color .16s ease;
}
.card:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); border-color: var(--border-strong); color: var(--c-blue-700); }
.card-title { font-weight: 650; }
.card-go { color: var(--muted); transition: transform .16s ease, color .16s ease; }
.card:hover .card-go { transform: translateX(4px); color: var(--c-blue); }
.subpages .card-grid { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }

.prevnext { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin-top: 2.5rem; }
.prevnext-link {
  display: flex; flex-direction: column; gap: .2rem;
  padding: 1rem 1.2rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-sm);
  transition: transform .16s ease, box-shadow .16s ease, border-color .16s ease;
}
.prevnext-link:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); border-color: var(--border-strong); }
.prevnext-link.next { text-align: right; }
.prevnext-dir { font-size: .78rem; text-transform: uppercase; letter-spacing: .06em; color: var(--c-sky); font-weight: 700; }
.prevnext-title { font-weight: 650; color: var(--ink); }

/* =========================================================================
   Content index page
   ========================================================================= */
.page-head { margin-bottom: 2.2rem; }
.page-title { font-size: clamp(1.9rem, 4.4vw, 2.9rem); font-weight: 800; letter-spacing: -0.025em; margin: 0 0 .6rem; }
.page-intro { max-width: 70ch; color: var(--ink-soft); font-size: 1.1rem; }

.index-section { margin-bottom: 2.5rem; }
.index-section-head {
  display: flex; align-items: center; gap: 1rem;
  padding: 1.2rem 1.4rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 5px solid var(--accent, var(--c-blue));
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  color: var(--ink);
  transition: transform .16s ease, box-shadow .16s ease;
}
.index-section-head:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); color: var(--ink); }
.index-ico {
  display: grid; place-items: center; flex: none;
  width: 50px; height: 50px; border-radius: 13px;
  color: #fff; background: var(--accent, var(--c-blue));
}
.index-ico .ico { width: 1.55em; height: 1.55em; }
.index-section-title { display: block; font-size: 1.25rem; font-weight: 750; letter-spacing: -0.01em; }
.index-section-blurb { display: block; color: var(--muted); font-size: .96rem; margin-top: .2rem; }

.index-children { list-style: none; margin: 1rem 0 0; padding: 0 0 0 1rem; display: grid; gap: .55rem; }
.index-child-link {
  display: inline-flex; align-items: center; gap: .5rem;
  padding: .55rem .7rem;
  border-radius: 9px;
  color: var(--ink-soft);
  font-weight: 600;
  transition: background-color .15s ease, color .15s ease, transform .12s ease;
}
.index-child-link:hover { background: var(--bg-soft); color: var(--c-blue); transform: translateX(3px); }
.index-child-link .ico { color: var(--c-sky); width: 1em; height: 1em; }
.index-grandchildren { list-style: none; margin: .25rem 0 .4rem; padding-left: 2rem; display: grid; gap: .25rem; }
.index-grandchildren a { color: var(--muted); font-size: .94rem; }
.index-grandchildren a:hover { color: var(--c-teal-700); }

/* =========================================================================
   Footer
   ========================================================================= */
.site-footer {
  flex-shrink: 0;
  margin-top: auto;
  background: #0f172a;
  color: #cbd5e1;
}
.footer-inner {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: 2rem;
  padding-block: 2.6rem 2rem;
}
.footer-brand { display: flex; gap: 1rem; align-items: flex-start; }
.footer-logo { border-radius: 10px; }
.footer-name { font-weight: 700; color: #fff; margin: 0 0 .3rem; }
.footer-tagline { margin: 0; color: #94a3b8; font-size: .92rem; max-width: 42ch; }
.footer-nav { display: grid; grid-template-columns: 1fr; gap: .3rem; }
.footer-heading { font-size: .78rem; text-transform: uppercase; letter-spacing: .08em; color: #64748b; margin: 1rem 0 .4rem; }
.footer-heading:first-child { margin-top: 0; }
.footer-nav ul { list-style: none; margin: 0; padding: 0; display: grid; gap: .15rem; }
.footer-nav a { display: inline-flex; align-items: center; gap: .5rem; color: #cbd5e1; padding: .3rem 0; font-weight: 500; }
.footer-nav a:hover { color: #fff; }
.footer-nav .ico { color: var(--c-sky); width: 1em; height: 1em; }
.footer-bottom { border-top: 1px solid #1e293b; padding-block: 1.2rem; }
.footer-bottom p { margin: 0; color: #64748b; font-size: .85rem; }

/* =========================================================================
   Responsive
   ========================================================================= */
@media (min-width: 1500px) {
  :root { --wrap: var(--wrap-wide); }
  body { font-size: 1.09rem; }
}

@media (max-width: 760px) {
  .nav-toggle { display: inline-flex; }
  .primary-nav {
    position: absolute;
    top: var(--header-h); left: 0; right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: .25rem;
    padding: .8rem clamp(1rem, 4vw, 2.5rem) 1.1rem;
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow-md);
    transform: translateY(-12px);
    opacity: 0;
    pointer-events: none;
    transition: transform .2s ease, opacity .2s ease;
  }
  .primary-nav.is-open { transform: translateY(0); opacity: 1; pointer-events: auto; }
  .nav-link { justify-content: flex-start; }
  .brand-sub { display: none; }
  .footer-inner { grid-template-columns: 1fr; gap: 1.4rem; }
  .prevnext { grid-template-columns: 1fr; }
}

@media (prefers-reduced-motion: reduce) {
  * { animation-duration: .001ms !important; transition-duration: .001ms !important; scroll-behavior: auto !important; }
}