/* ===== ROOT TOKENS ===== */
:root {
  --bg: #0b0c13;
  --surface: #13141f;
  --surface2: #1a1c2a;
  --surface3: #1f2133;
  --glass-bg: rgba(22, 26, 42, 0.58);
  --glass-bg-strong: rgba(26, 31, 50, 0.72);
  --glass-border: rgba(255, 255, 255, 0.14);
  --glass-shadow: 0 14px 38px rgba(0, 0, 0, 0.38);
  --border: rgba(255,255,255,0.07);
  --border-hover: rgba(245,166,35,0.4);
  --amber: #f5a623;
  --amber-dim: rgba(245,166,35,0.13);
  --amber-glow: rgba(245,166,35,0.06);
  --cyan: #5cf0d0;
  --cyan-dim: rgba(92,240,208,0.1);
  --text: #e8e4da;
  --muted: #7a7670;
  --muted2: #4e4b46;
  --green: #6ee46e;
  --green-dim: rgba(110,228,110,0.1);
  --purple: #b893ff;
  --purple-dim: rgba(184,147,255,0.1);
  --coral: #ff8b6b;
  --coral-dim: rgba(255,139,107,0.1);
  --red: #ff6b6b;
}

/* ===== LIGHT THEME ===== */
[data-theme="light"] {
  --bg: #f0ede6;
  --surface: #faf9f7;
  --surface2: #e8e4da;
  --surface3: #dedad0;
  --glass-bg: rgba(250, 249, 247, 0.72);
  --glass-bg-strong: rgba(240, 237, 230, 0.88);
  --glass-border: rgba(0, 0, 0, 0.12);
  --glass-shadow: 0 10px 28px rgba(0, 0, 0, 0.10);
  --border: rgba(0,0,0,0.09);
  --border-hover: rgba(180,100,10,0.45);
  --amber: #b86e00;
  --amber-dim: rgba(184,110,0,0.12);
  --amber-glow: rgba(184,110,0,0.05);
  --cyan: #0b7a6d;
  --cyan-dim: rgba(11,122,109,0.10);
  --text: #1c1b18;
  --muted: #6a635c;
  --muted2: #a8a09a;
  --green: #1f7e1f;
  --green-dim: rgba(31,126,31,0.10);
  --purple: #6b3dba;
  --purple-dim: rgba(107,61,186,0.10);
  --coral: #b84020;
  --coral-dim: rgba(184,64,32,0.10);
  --red: #bb2222;
}

[data-theme="light"] body {
  background:
    radial-gradient(1200px 520px at 10% -20%, rgba(11,122,109,0.07), transparent 55%),
    radial-gradient(900px 460px at 90% -15%, rgba(184,110,0,0.09), transparent 62%),
    var(--bg);
}

[data-theme="light"] body::before { background: none; }

[data-theme="light"] .prose code {
  background: rgba(0,0,0,0.06);
  border-color: rgba(0,0,0,0.12);
}

[data-theme="light"] .prose pre,
[data-theme="light"] .prose pre code {
  color: #1c1b18;
}

[data-theme="light"] .mermaid .node rect,
[data-theme="light"] .mermaid .node circle,
[data-theme="light"] .mermaid .node polygon,
[data-theme="light"] .mermaid .node path { fill: #e8e4da !important; stroke: #b86e00 !important; }
[data-theme="light"] .mermaid .label { fill: #1c1b18 !important; }
[data-theme="light"] .mermaid .edgePath .path { stroke: #a8a09a !important; }
[data-theme="light"] .mermaid .edgeLabel { background: #f0ede6 !important; color: #6a635c !important; }

.theme-toggle {
  background: transparent;
  border: 1px solid var(--glass-border);
  border-radius: 4px;
  width: 30px; height: 30px;
  display: flex; align-items: center; justify-content: center;
  cursor: pointer;
  color: var(--muted);
  font-size: 15px;
  flex-shrink: 0;
  transition: border-color .2s, color .2s;
}
.theme-toggle:hover {
  border-color: var(--border-hover);
  color: var(--amber);
}



/* ===== RESET ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  background:
    radial-gradient(1200px 520px at 10% -20%, rgba(92,240,208,0.10), transparent 55%),
    radial-gradient(900px 460px at 90% -15%, rgba(245,166,35,0.12), transparent 62%),
    var(--bg);
  color: var(--text);
  font-family: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;
  font-size: 14px;
  line-height: 1.7;
  min-height: 100vh;
}
body::before {
  content: '';
  position: fixed; inset: 0;
  background: repeating-linear-gradient(
    to bottom, transparent 0px, transparent 3px,
    rgba(0,0,0,0.03) 3px, rgba(0,0,0,0.03) 4px
  );
  pointer-events: none;
  z-index: 9999;
}

/* ===== NAV ===== */
.site-nav {
  position: fixed; top: 0; left: 0; right: 0;
  z-index: 100;
  background: var(--glass-bg-strong);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--glass-border);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.25);
  display: flex; align-items: center; gap: 1rem;
  padding: 0 2rem;
  height: 52px;
}
.nav-home {
  display: flex; align-items: center; gap: 8px;
  text-decoration: none;
  color: var(--text);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  flex-shrink: 0;
}
.nav-home .dot {
  width: 7px; height: 7px;
  background: var(--amber);
  border-radius: 50%;
  animation: blink 1.8s ease-in-out infinite;
}
@keyframes blink { 0%,100%{opacity:1} 50%{opacity:.2} }
.nav-sep { color: var(--muted2); font-size: 18px; }
.nav-breadcrumb {
  color: var(--muted);
  font-size: 11px;
  letter-spacing: 0.05em;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.nav-right {
  margin-left: auto;
  display: flex; align-items: center; gap: 1rem;
}
.nav-links-sm { display: flex; gap: 1.5rem; list-style: none; }
.nav-links-sm a {
  color: var(--muted);
  text-decoration: none;
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  transition: color 0.2s;
}
.nav-links-sm a:hover { color: var(--amber); }
.nav-tag {
  font-size: 9px;
  padding: 3px 10px;
  border-radius: 2px;
  letter-spacing: 0.12em;
  font-weight: 700;
  white-space: nowrap;
}
.reading-bar {
  position: fixed; top: 52px; left: 0;
  height: 2px; background: var(--amber);
  z-index: 200; width: 0%; transition: width .1s linear;
}

/* ===== LAYOUT ===== */
.page-wrap {
  max-width: 1120px;
  margin: 0 auto;
  padding: 88px 2rem 6rem;
}
.page-wrap-wide {
  max-width: 1320px;
  margin: 0 auto;
  padding: 88px 2rem 6rem;
}

/* ===== CHAPTER HEADER ===== */
.chapter-header {
  border-bottom: 1px solid var(--border);
  padding-bottom: 2.5rem;
  margin-bottom: 3rem;
}
.chapter-eyebrow {
  display: inline-flex; align-items: center; gap: 8px;
  font-size: 10px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--amber);
  margin-bottom: 1.2rem;
}
.chapter-eyebrow::before {
  content: '';
  width: 5px; height: 5px;
  background: var(--amber);
  border-radius: 50%;
}
.chapter-title-h1 {
  font-family: 'Fraunces', Georgia, serif;
  font-size: clamp(2.2rem, 5vw, 3.5rem);
  font-weight: 300;
  line-height: 1.1;
  color: #fff;
  margin-bottom: 1rem;
  letter-spacing: -0.02em;
}
.chapter-meta {
  display: flex; flex-wrap: wrap; gap: 1.5rem;
  color: var(--muted);
  font-size: 11px;
  letter-spacing: 0.05em;
}
.chapter-meta span { display: flex; align-items: center; gap: 6px; }

/* ===== TAGS ===== */
.tag {
  display: inline-block;
  font-size: 9px;
  padding: 3px 8px;
  border-radius: 2px;
  letter-spacing: 0.1em;
  font-weight: 700;
  text-transform: uppercase;
}
.tag-core    { background: var(--amber-dim);  color: var(--amber);  border: 1px solid rgba(245,166,35,.2); }
.tag-tools   { background: var(--cyan-dim);   color: var(--cyan);   border: 1px solid rgba(92,240,208,.2); }
.tag-security{ background: var(--green-dim);  color: var(--green);  border: 1px solid rgba(110,228,110,.2); }
.tag-advanced{ background: var(--purple-dim); color: var(--purple); border: 1px solid rgba(184,147,255,.2); }
.tag-agents  { background: var(--coral-dim);  color: var(--coral);  border: 1px solid rgba(255,139,107,.2); }

/* ===== PROSE CONTENT ===== */
.prose { max-width: 980px; }
.prose > p,
.prose > ul,
.prose > ol,
.prose > blockquote,
.prose > h1,
.prose > h2,
.prose > h3,
.prose > h4,
.prose > hr {
  max-width: 760px;
}
.prose h1 {
  font-family: 'Fraunces', Georgia, serif;
  font-size: 2rem; font-weight: 300;
  color: #fff; margin: 2.5rem 0 1rem;
  line-height: 1.2; letter-spacing: -0.01em;
}
.prose h2 {
  font-family: 'Fraunces', Georgia, serif;
  font-size: 1.5rem; font-weight: 300;
  color: #fff; margin: 2.5rem 0 .8rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  line-height: 1.3;
}
.prose h3 {
  font-size: 1rem; font-weight: 700;
  color: var(--text); margin: 1.8rem 0 .6rem;
  letter-spacing: 0.05em;
}
.prose h4 {
  font-size: .85rem; font-weight: 700;
  color: var(--amber); margin: 1.5rem 0 .5rem;
  letter-spacing: 0.08em; text-transform: uppercase;
}
.prose p { margin-bottom: 1.2rem; color: var(--text); line-height: 1.85; }
.prose ul, .prose ol { margin: 1rem 0 1.2rem 1.5rem; }
.prose li { margin-bottom: .5rem; color: var(--text); line-height: 1.8; }
.prose li::marker { color: var(--amber); }
.prose a { color: var(--cyan); text-decoration: none; border-bottom: 1px solid rgba(92,240,208,.3); transition: border-color .2s; }
.prose a:hover { border-color: var(--cyan); }
.prose strong { color: #fff; font-weight: 700; }
.prose em { color: var(--amber); font-style: italic; }
.prose blockquote {
  border-left: 2px solid var(--amber);
  margin: 1.5rem 0; padding: .8rem 1.5rem;
  background: var(--amber-glow);
  border-radius: 0 4px 4px 0;
  color: var(--muted);
  font-style: italic;
}
.prose hr { border: none; border-top: 1px solid var(--border); margin: 2.5rem 0; }

/* ===== CODE ===== */
.prose code {
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
  font-size: .85em;
  background: var(--surface2);
  color: var(--cyan);
  padding: 2px 6px;
  border-radius: 3px;
  border: 1px solid var(--border);
}
.prose pre {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  box-shadow: var(--glass-shadow);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-radius: 6px;
  padding: 1.25rem 1.5rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  position: relative;
}
.prose pre::before {
  content: attr(data-lang);
  position: absolute; top: 8px; right: 12px;
  font-size: 9px; letter-spacing: .1em;
  text-transform: uppercase; color: var(--muted2);
}
.prose pre code {
  background: none; color: var(--text);
  padding: 0; border: none;
  font-size: .82rem; line-height: 1.7;
}

/* ===== MERMAID ===== */
.mermaid-wrap {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  box-shadow: var(--glass-shadow);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-radius: 6px;
  padding: 1.75rem;
  margin: 1.5rem 0;
  overflow-x: auto;
  overflow-y: hidden;
  width: 100%;
  position: relative;
  --mermaid-scale: 1;
}
.mermaid {
  font-family: 'JetBrains Mono', monospace !important;
  min-width: 980px;
}
.mermaid svg {
  display: block;
  width: max-content !important;
  max-width: none !important;
  min-width: 980px;
  height: auto !important;
  transform-origin: top left;
  transform: translate(var(--mermaid-pan-x, 0px), var(--mermaid-pan-y, 0px)) scale(var(--mermaid-scale, 1));
  transition: transform 0.05s ease-out;
}

.mermaid-toolbar {
  position: sticky;
  top: 8px;
  right: 0;
  margin-left: auto;
  width: max-content;
  z-index: 5;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px;
  border: 1px solid var(--glass-border);
  border-radius: 6px;
  background: var(--glass-bg-strong);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.28);
  opacity: 0;
  transform: translateY(-4px);
  pointer-events: none;
  transition: opacity .2s ease, transform .2s ease;
}

.mermaid-wrap.show-toolbar .mermaid-toolbar,
.mermaid-wrap.panning-mode .mermaid-toolbar,
.mermaid-wrap:fullscreen .mermaid-toolbar,
.mermaid-wrap.is-pseudo-fullscreen .mermaid-toolbar {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.mermaid-toolbar .icon-btn {
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text);
  border-radius: 4px;
  width: 28px;
  height: 28px;
  padding: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all 0.15s ease;
  flex-shrink: 0;
}

.mermaid-toolbar .icon-btn:hover {
  border-color: var(--border-hover);
  color: var(--amber);
  background: rgba(245,166,35,0.08);
}

.mermaid-toolbar .icon-btn:active,
.mermaid-toolbar .icon-btn.active {
  background: rgba(245,166,35,0.15);
  border-color: var(--amber);
}

.mermaid-toolbar .icon-btn svg {
  display: block;
  width: 16px;
  height: 16px;
}

.mermaid-zoom-label {
  min-width: 38px;
  text-align: center;
  font-size: 10px;
  color: var(--muted);
  font-weight: 500;
  padding: 0 4px;
  user-select: none;
}

.mermaid-wrap.panning-mode svg {
  cursor: grab;
}

.mermaid-wrap.panning-mode svg:active {
  cursor: grabbing;
}

.mermaid-wrap:fullscreen,
.mermaid-wrap:-webkit-full-screen,
.mermaid-wrap.is-pseudo-fullscreen {
  position: fixed;
  inset: 0;
  margin: 0;
  border-radius: 0;
  border: none;
  z-index: 10000;
  padding: 1rem;
  background: var(--bg);
}
/* Override mermaid defaults for dark mode */
.mermaid .label { fill: #e8e4da !important; }
.mermaid .node rect, .mermaid .node circle, .mermaid .node polygon,
.mermaid .node path { fill: #1a1c2a !important; stroke: #f5a623 !important; }
.mermaid .edgePath .path { stroke: #7a7670 !important; }
.mermaid .edgeLabel { background: #0b0c13 !important; color: #7a7670 !important; }

/* ===== TABLES ===== */
.prose table {
  width: 100%; border-collapse: collapse;
  margin: 1.5rem 0; font-size: 12px;
}
.prose th {
  background: var(--surface2);
  color: var(--amber);
  padding: 10px 14px; text-align: left;
  font-size: 10px; letter-spacing: .1em;
  text-transform: uppercase;
  border-bottom: 1px solid var(--border);
}
.prose td {
  padding: 10px 14px;
  border-bottom: 1px solid var(--border);
  color: var(--text); vertical-align: top;
}
.prose tr:hover td { background: var(--surface); }

/* ===== NAV CARDS (prev/next) ===== */
.chapter-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 4rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
}
.chapter-nav-card {
  display: block;
  padding: 1.2rem 1.5rem;
  border: 1px solid var(--glass-border);
  border-radius: 4px;
  text-decoration: none;
  background: var(--glass-bg);
  box-shadow: var(--glass-shadow);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  transition: border-color .2s, background .2s;
  position: relative;
}
.chapter-nav-card:hover {
  border-color: var(--border-hover);
  background: rgba(33, 39, 62, 0.74);
}
.chapter-nav-card.next {
  text-align: right;
  grid-column: 2;
}
.chapter-nav-label {
  font-size: 9px; letter-spacing: .15em;
  text-transform: uppercase; color: var(--muted);
  margin-bottom: 4px;
}
.chapter-nav-title {
  font-family: 'Fraunces', Georgia, serif;
  font-size: 1rem; color: #fff; font-weight: 300;
}

/* ===== TOC & SIDEBAR ===== */
.page-with-toc {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 220px;
  gap: 3rem;
  align-items: start;
  max-width: 1320px;
  margin: 0 auto;
  padding: 88px 2rem 6rem;
}
.page-with-rails {
  --left-rail-width: 290px;
  display: grid;
  grid-template-columns: var(--left-rail-width) minmax(0, 1fr) 220px;
  gap: 2rem;
  align-items: start;
  max-width: 1640px;
  margin: 0 auto;
  padding: 88px 2rem 6rem;
  transition: grid-template-columns .2s ease;
}
.page-with-rails.left-collapsed {
  --left-rail-width: 56px;
}
.page-with-rails.left-collapsed.left-hover {
  --left-rail-width: 290px;
}
@media (max-width: 900px) {
  .page-with-toc, .page-with-rails { grid-template-columns: 1fr; }
  .toc-sidebar { display: none; }
  .left-sidebar { display: none; }
}
.toc-sidebar {
  position: sticky; top: 72px;
  border: 1px solid var(--glass-border);
  border-radius: 4px;
  padding: 1rem;
  background: var(--glass-bg);
  box-shadow: var(--glass-shadow);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  font-size: 11px;
}
.toc-title {
  font-size: 9px; letter-spacing: .15em;
  text-transform: uppercase; color: var(--muted);
  margin-bottom: .8rem;
}
.toc-list { list-style: none; }
.toc-list li { margin-bottom: .4rem; }
.toc-list a {
  color: var(--muted);
  text-decoration: none;
  transition: color .2s;
  display: block;
  padding: 2px 0;
  line-height: 1.4;
}
.toc-list a:hover { color: var(--amber); }
.toc-list a.active {
  color: var(--amber);
  font-weight: 600;
}

/* ===== LEFT SIDEBAR (Chapters & Subsystems) ===== */
.left-sidebar {
  position: sticky;
  top: 72px;
  z-index: 6;
}
.left-sidebar-inner {
  border: 1px solid var(--glass-border);
  border-radius: 4px;
  padding: 1rem;
  max-height: calc(100vh - 88px);
  overflow-y: auto;
  background: var(--glass-bg);
  box-shadow: var(--glass-shadow);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  transition: padding .2s ease;
}
.left-sidebar-controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: .5rem;
  margin-bottom: .8rem;
}
.left-sidebar-pin-btn {
  border: 1px solid var(--glass-border);
  border-radius: 3px;
  background: transparent;
  color: var(--muted);
  font-size: 9px;
  letter-spacing: .12em;
  padding: .3rem .42rem;
  cursor: pointer;
  transition: color .2s, border-color .2s, background .2s;
}
.left-sidebar-pin-btn:hover {
  color: var(--amber);
  border-color: var(--border-hover);
  background: rgba(245, 166, 35, 0.08);
}
.left-sidebar-hint {
  color: var(--muted2);
  font-size: 9px;
  letter-spacing: .08em;
  text-transform: uppercase;
}
.left-nav-section-toggle {
  width: 100%;
  border: none;
  background: transparent;
  color: var(--muted);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: .2rem 0;
  margin-bottom: .45rem;
  font-size: 9px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .15em;
  cursor: pointer;
  text-align: left;
}
.left-nav-section-toggle:hover {
  color: var(--amber);
}
.left-nav-chevron {
  font-size: 10px;
  letter-spacing: 0;
  transition: transform .2s ease;
}
.left-nav-section-toggle[aria-expanded="false"] .left-nav-chevron {
  transform: rotate(-90deg);
}
.left-nav-subsystem-toggle {
  width: 100%;
  justify-content: space-between;
  border: none;
  background: transparent;
  cursor: pointer;
}
.left-nav-subsystem-toggle .left-nav-subsystem-text {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}
.left-nav-subsystem-toggle[aria-expanded="false"] .left-nav-chevron {
  transform: rotate(-90deg);
}
.left-nav-subsystem-body[hidden] {
  display: none;
}
.left-nav-body[hidden] {
  display: none;
}
.left-nav-group + .left-nav-group {
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
}
.left-nav-list {
  list-style: none;
}
.left-nav-list li {
  margin: 0;
}
.left-nav-link {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.35rem 0.5rem;
  color: var(--muted);
  text-decoration: none;
  font-size: 12px;
  line-height: 1.4;
  transition: color .2s, background .2s;
  border-radius: 3px;
  position: relative;
}
.left-nav-link:hover {
  color: var(--amber);
  background: rgba(245, 166, 35, 0.08);
}
.left-nav-link.active {
  color: var(--amber);
  background: rgba(245, 166, 35, 0.12);
  font-weight: 600;
}
.left-nav-index {
  display: inline-block;
  font-size: 10px;
  font-weight: 700;
  min-width: 1.8rem;
  color: var(--muted2);
}
.left-nav-sublist {
  list-style: none;
  margin: 0.4rem 0 0 1.4rem;
  padding: 0;
  border-left: 1px solid var(--border);
  padding-left: 0.8rem;
  margin-left: 0.6rem;
}
.left-nav-sublink {
  display: block;
  padding: 0.25rem 0.5rem;
  color: var(--muted2);
  font-size: 11px;
  text-decoration: none;
  transition: color .2s;
  line-height: 1.3;
}
.left-nav-sublink:hover {
  color: var(--amber);
}
.left-nav-sublink.active {
  color: var(--amber);
  font-weight: 600;
  background: rgba(245, 166, 35, 0.12);
  border-radius: 3px;
}

.page-with-rails.left-collapsed:not(.left-hover) .left-sidebar-inner {
  padding: .65rem .35rem;
}
.page-with-rails.left-collapsed:not(.left-hover) .left-sidebar-hint,
.page-with-rails.left-collapsed:not(.left-hover) .left-nav-body,
.page-with-rails.left-collapsed:not(.left-hover) .left-nav-title-text,
.page-with-rails.left-collapsed:not(.left-hover) .left-nav-chevron {
  display: none;
}
.page-with-rails.left-collapsed:not(.left-hover) .left-sidebar-controls {
  justify-content: center;
}
.page-with-rails.left-collapsed:not(.left-hover) .left-sidebar-pin-btn {
  writing-mode: vertical-rl;
  transform: rotate(180deg);
  letter-spacing: .08em;
  padding: .35rem .2rem;
}
.page-with-rails.left-collapsed:not(.left-hover) .left-nav-group + .left-nav-group {
  margin-top: .5rem;
  padding-top: .5rem;
}

/* ===== SUBSYSTEM INDEX CARDS ===== */
.subsystem-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: 4px;
  overflow: hidden;
  margin: 2rem 0;
}
.sub-file-card {
  background: var(--glass-bg);
  padding: 1.5rem;
  text-decoration: none;
  display: block;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  transition: background .2s;
  position: relative;
}
.sub-file-card::before {
  content: '';
  position: absolute; left: 0; top: 0; bottom: 0;
  width: 2px; background: transparent;
  transition: background .2s;
}
.sub-file-card:hover { background: var(--surface2); }
.sub-file-card:hover::before { background: var(--amber); }
.sub-file-name {
  font-size: 11px; font-weight: 700;
  letter-spacing: .06em; color: var(--amber);
  margin-bottom: 6px;
}
.sub-file-title {
  font-family: 'Fraunces', Georgia, serif;
  font-size: 1rem; font-weight: 400;
  color: #fff; margin-bottom: 6px;
}
.sub-file-desc { font-size: 10px; color: var(--muted); line-height: 1.6; }

/* ===== FOOTER ===== */
.site-footer {
  border-top: 1px solid var(--glass-border);
  padding: 2rem 2rem;
  display: flex; align-items: center;
  justify-content: space-between; flex-wrap: wrap; gap: 1rem;
  font-size: 11px; color: var(--muted2);
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}
.site-footer a { color: var(--muted); text-decoration: none; transition: color .2s; }
.site-footer a:hover { color: var(--amber); }

/* ===== RESPONSIVE ===== */
@media (max-width: 600px) {
  .site-nav { padding: 0 1rem; }
  .nav-links-sm { display: none; }
  .page-wrap, .page-with-toc, .page-with-rails { padding: 72px 1rem 4rem; }
  .chapter-nav { grid-template-columns: 1fr; }
  .chapter-nav-card.next { grid-column: auto; }
  .mermaid,
  .mermaid svg {
    min-width: 640px;
  }
}

/* ===== LIGHT THEME VISIBILITY FIXES ===== */
/* Fix hardcoded #fff text that vanishes on parchment background */
[data-theme="light"] .chapter-title-h1 { color: #1c1b18; }
[data-theme="light"] .hero-h1 { color: #1c1b18; }
[data-theme="light"] .sec-h2 { color: #1c1b18; }
[data-theme="light"] .ch-title { color: #1c1b18; }
[data-theme="light"] .sub-title { color: #1c1b18; }
[data-theme="light"] .ch-card:hover { background: rgba(200,196,186,0.55); }
[data-theme="light"] .sub-card { background: var(--surface); }
[data-theme="light"] .prose h1,
[data-theme="light"] .prose h2 { color: #1c1b18; }
[data-theme="light"] .prose strong { color: #1c1b18; }
[data-theme="light"] .sub-file-title { color: #1c1b18; }
[data-theme="light"] .chapter-nav-title { color: #1c1b18; }

/* Fix nav card hover (hardcoded dark rgba) */
[data-theme="light"] .chapter-nav-card:hover { background: rgba(200, 196, 186, 0.55); }

/* Fix prose link underline (hardcoded dark-mode cyan rgba) */
[data-theme="light"] .prose a { border-bottom-color: rgba(11,122,109,.3); }

/* Fix tag borders (hardcoded dark-mode rgba) */
[data-theme="light"] .tag-core    { border-color: rgba(184,110,0,.3); }
[data-theme="light"] .tag-tools   { border-color: rgba(11,122,109,.3); }
[data-theme="light"] .tag-security{ border-color: rgba(31,126,31,.3); }
[data-theme="light"] .tag-advanced{ border-color: rgba(107,61,186,.3); }
[data-theme="light"] .tag-agents  { border-color: rgba(184,64,32,.3); }

/* Fix mermaid toolbar icon button hover/active backgrounds */
[data-theme="light"] .mermaid-toolbar .icon-btn:hover {
  background: rgba(184,110,0,0.09);
}
[data-theme="light"] .mermaid-toolbar .icon-btn:active,
[data-theme="light"] .mermaid-toolbar .icon-btn.active {
  background: rgba(184,110,0,0.16);
  border-color: var(--amber);
}

/* Fix mermaid SEQUENCE diagram SVG inline dark styles */
[data-theme="light"] .mermaid svg .actor                             { stroke: #0b7a6d !important; fill: #e8e4da !important; }
[data-theme="light"] .mermaid svg text.actor > tspan                { fill: #1c1b18 !important; stroke: none !important; }
[data-theme="light"] .mermaid svg .actor-line                        { stroke: rgba(0,0,0,0.25) !important; }
[data-theme="light"] .mermaid svg .messageLine0                      { stroke: #6a635c !important; }
[data-theme="light"] .mermaid svg .messageLine1                      { stroke: #6a635c !important; }
[data-theme="light"] .mermaid svg .messageText                       { fill: #1c1b18 !important; stroke: none !important; }
[data-theme="light"] .mermaid svg .labelBox                          { stroke: #0b7a6d !important; fill: #e8e4da !important; }
[data-theme="light"] .mermaid svg .labelText,
[data-theme="light"] .mermaid svg .labelText > tspan                { fill: #1c1b18 !important; stroke: none !important; }
[data-theme="light"] .mermaid svg .loopText,
[data-theme="light"] .mermaid svg .loopText > tspan                 { fill: #1c1b18 !important; stroke: none !important; }
[data-theme="light"] .mermaid svg .loopLine                          { stroke: #0b7a6d !important; fill: transparent !important; }
[data-theme="light"] .mermaid svg .note                              { stroke: #b86e00 !important; fill: #f5f0e0 !important; }
[data-theme="light"] .mermaid svg .noteText,
[data-theme="light"] .mermaid svg .noteText > tspan                 { fill: #1c1b18 !important; stroke: none !important; }
[data-theme="light"] .mermaid svg .activation0,
[data-theme="light"] .mermaid svg .activation1,
[data-theme="light"] .mermaid svg .activation2                      { fill: #dedad0 !important; stroke: #0b7a6d !important; }
[data-theme="light"] .mermaid svg #arrowhead path,
[data-theme="light"] .mermaid svg #crosshead path                   { fill: #6a635c !important; stroke: #6a635c !important; }
[data-theme="light"] .mermaid svg .sequenceNumber                   { fill: #f0ede6 !important; }

/* Fix mermaid FLOWCHART text color in light theme */
[data-theme="light"] .mermaid svg text,
[data-theme="light"] .mermaid svg tspan,
[data-theme="light"] .mermaid svg .label,
[data-theme="light"] .mermaid svg .label text,
[data-theme="light"] .mermaid svg .nodeLabel,
[data-theme="light"] .mermaid svg .flowchartTitleText,
[data-theme="light"] .mermaid svg .cluster-label text,
[data-theme="light"] .mermaid svg .edgeLabel span,
[data-theme="light"] .mermaid svg .edgeLabel div,
[data-theme="light"] .mermaid svg foreignObject span,
[data-theme="light"] .mermaid svg foreignObject div {
  fill: #1c1b18 !important;
  color: #1c1b18 !important;
}

[data-theme="light"] .mermaid svg .edgeLabel,
[data-theme="light"] .mermaid svg .edgeLabel rect,
[data-theme="light"] .mermaid svg .labelBkg {
  background: #f0ede6 !important;
  fill: #f0ede6 !important;
}