/* The Incin Book - mdBook / Rustnomicon Single Page Application Stylesheet */

/* ==========================================================================
   Themes & Design Tokens
   ========================================================================== */

:root {
  --sidebar-width: 280px;
  --menu-bar-height: 50px;
  --content-max-width: 820px;
  --font-body: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
  --font-mono: "Source Code Pro", "Fira Code", Menlo, Monaco, Consolas, "Ubuntu Mono", "DejaVu Sans Mono", monospace;
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;
  --transition-fast: 0.15s ease;
}

/* 1. Navy Theme (Default) */
html.navy, :root[data-theme="navy"] {
  --bg: hsl(226, 23%, 11%);
  --fg: #bcbdd0;
  --fg-heading: #e8edf2;
  --sidebar-bg: #282d3f;
  --sidebar-fg: #c8c9db;
  --sidebar-active: #2b79a2;
  --sidebar-active-bg: rgba(43, 121, 162, 0.25);
  --sidebar-hover: rgba(255, 255, 255, 0.06);
  --sidebar-border: #353b52;
  --sidebar-group: #8f93a8;
  --menu-bar-bg: #282d3f;
  --menu-bar-border: #353b52;
  --scrollbar: #464c66;
  --icons: #8f93a8;
  --icons-hover: #ffffff;
  --links: #64b5f6;
  --links-hover: #90caf9;
  --inline-code-bg: #1e2230;
  --inline-code-fg: #f39c12;
  --code-bg: #161923;
  --code-fg: #c5c8c6;
  --code-border: #282d3f;
  --code-header-bg: #1e2230;
  --quote-bg: hsl(226, 15%, 17%);
  --quote-border: #2b79a2;
  --table-border: #353b52;
  --table-header-bg: hsl(226, 23%, 24%);
  --table-alt-bg: hsl(226, 23%, 14%);
  --searchbar-bg: #1e2230;
  --searchbar-fg: #e8edf2;
  --searchbar-border: #464c66;
  --search-popup-bg: #1e2230;
  --search-popup-border: #353b52;
  --search-highlight: #f39c12;
  --theme-popup-bg: #1e2230;
  --theme-popup-border: #353b52;
  --terminal-bg: #0d0f17;
  --terminal-border: #282d3f;
  --focus-ring: #2b79a2;
  color-scheme: dark;
}

/* 2. Rust Theme (Iconic Rustnomicon Look) */
html.rust, :root[data-theme="rust"] {
  --bg: hsl(60, 9%, 87%);
  --fg: #262625;
  --fg-heading: #1a1a19;
  --sidebar-bg: #3b2e2a;
  --sidebar-fg: #c8c9db;
  --sidebar-active: #e69f67;
  --sidebar-active-bg: rgba(230, 159, 103, 0.2);
  --sidebar-hover: rgba(255, 255, 255, 0.08);
  --sidebar-border: #4d3d38;
  --sidebar-group: #a69b97;
  --menu-bar-bg: #3b2e2a;
  --menu-bar-border: #4d3d38;
  --scrollbar: #5c4943;
  --icons: #c8c9db;
  --icons-hover: #ffffff;
  --links: #8b4513;
  --links-hover: #b35917;
  --inline-code-bg: #deded6;
  --inline-code-fg: #8b3a1a;
  --code-bg: #e1e1db;
  --code-fg: #262625;
  --code-border: #b3a497;
  --code-header-bg: #d6d6ce;
  --quote-bg: hsl(60, 5%, 80%);
  --quote-border: #b35917;
  --table-border: #b3a497;
  --table-header-bg: #b3a497;
  --table-alt-bg: hsl(60, 9%, 84%);
  --searchbar-bg: #fafafa;
  --searchbar-fg: #262625;
  --searchbar-border: #b3a497;
  --search-popup-bg: #e1e1db;
  --search-popup-border: #b3a497;
  --search-highlight: #e69f67;
  --theme-popup-bg: #e1e1db;
  --theme-popup-border: #b38f6b;
  --terminal-bg: #292421;
  --terminal-border: #3b2e2a;
  --focus-ring: #e69f67;
  color-scheme: light;
}

/* 3. Light Theme */
html.light, :root[data-theme="light"] {
  --bg: #ffffff;
  --fg: #222222;
  --fg-heading: #111111;
  --sidebar-bg: #fafafa;
  --sidebar-fg: #333333;
  --sidebar-active: #1f1fff;
  --sidebar-active-bg: rgba(31, 31, 255, 0.08);
  --sidebar-hover: rgba(0, 0, 0, 0.04);
  --sidebar-border: #e6e6e6;
  --sidebar-group: #666666;
  --menu-bar-bg: #fafafa;
  --menu-bar-border: #e6e6e6;
  --scrollbar: #cccccc;
  --icons: #747474;
  --icons-hover: #000000;
  --links: #20609f;
  --links-hover: #124070;
  --inline-code-bg: #f3f4f6;
  --inline-code-fg: #c7254e;
  --code-bg: #f8f9fa;
  --code-fg: #24292e;
  --code-border: #e1e4e8;
  --code-header-bg: #eaecef;
  --quote-bg: hsl(197, 37%, 96%);
  --quote-border: #20609f;
  --table-border: #e1e4e8;
  --table-header-bg: #f1f3f5;
  --table-alt-bg: #f8f9fa;
  --searchbar-bg: #ffffff;
  --searchbar-fg: #222222;
  --searchbar-border: #cccccc;
  --search-popup-bg: #ffffff;
  --search-popup-border: #cccccc;
  --search-highlight: #ffdf7e;
  --theme-popup-bg: #ffffff;
  --theme-popup-border: #cccccc;
  --terminal-bg: #1f2428;
  --terminal-border: #24292e;
  --focus-ring: #20609f;
  color-scheme: light;
}

/* 4. Coal Theme */
html.coal, :root[data-theme="coal"] {
  --bg: hsl(200, 7%, 8%);
  --fg: #98a3ad;
  --fg-heading: #e2e8f0;
  --sidebar-bg: #292c2f;
  --sidebar-fg: #a1adb8;
  --sidebar-active: #3473ad;
  --sidebar-active-bg: rgba(52, 115, 173, 0.25);
  --sidebar-hover: rgba(255, 255, 255, 0.05);
  --sidebar-border: #383c40;
  --sidebar-group: #75808a;
  --menu-bar-bg: #292c2f;
  --menu-bar-border: #383c40;
  --scrollbar: #4a5056;
  --icons: #828e99;
  --icons-hover: #e2e8f0;
  --links: #4da3d4;
  --links-hover: #7bc0e8;
  --inline-code-bg: #1a1c1e;
  --inline-code-fg: #e2b36f;
  --code-bg: #141617;
  --code-fg: #c5c8c6;
  --code-border: #292c2f;
  --code-header-bg: #1f2124;
  --quote-bg: hsl(234, 21%, 18%);
  --quote-border: #3473ad;
  --table-border: #383c40;
  --table-header-bg: #1e2124;
  --table-alt-bg: #121415;
  --searchbar-bg: #1f2124;
  --searchbar-fg: #e2e8f0;
  --searchbar-border: #4a5056;
  --search-popup-bg: #1f2124;
  --search-popup-border: #383c40;
  --search-highlight: #3473ad;
  --theme-popup-bg: #1f2124;
  --theme-popup-border: #43484d;
  --terminal-bg: #0c0d0e;
  --terminal-border: #1f2124;
  --focus-ring: #3473ad;
  color-scheme: dark;
}

/* 5. Ayu Theme */
html.ayu, :root[data-theme="ayu"] {
  --bg: hsl(210, 25%, 8%);
  --fg: #c5c5c5;
  --fg-heading: #f0f0f0;
  --sidebar-bg: #14191f;
  --sidebar-fg: #c8c9db;
  --sidebar-active: #ffb454;
  --sidebar-active-bg: rgba(255, 180, 84, 0.15);
  --sidebar-hover: rgba(255, 255, 255, 0.05);
  --sidebar-border: #1f242c;
  --sidebar-group: #737b85;
  --menu-bar-bg: #14191f;
  --menu-bar-border: #1f242c;
  --scrollbar: #2d3440;
  --icons: #737b85;
  --icons-hover: #ffb454;
  --links: #39bae6;
  --links-hover: #59cbe8;
  --inline-code-bg: #101419;
  --inline-code-fg: #ffb454;
  --code-bg: #0f141c;
  --code-fg: #e6e1cf;
  --code-border: #1f242c;
  --code-header-bg: #151b23;
  --quote-bg: hsl(226, 15%, 17%);
  --quote-border: #ffb454;
  --table-border: #1f242c;
  --table-header-bg: #19202a;
  --table-alt-bg: #0b0f14;
  --searchbar-bg: #151b23;
  --searchbar-fg: #f0f0f0;
  --searchbar-border: #2d3440;
  --search-popup-bg: #151b23;
  --search-popup-border: #1f242c;
  --search-highlight: #ffb454;
  --theme-popup-bg: #14191f;
  --theme-popup-border: #2d3440;
  --terminal-bg: #0a0d12;
  --terminal-border: #1f242c;
  --focus-ring: #ffb454;
  color-scheme: dark;
}

/* ==========================================================================
   Base & Reset
   ========================================================================== */

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  background-color: var(--bg);
}

body {
  margin: 0;
  padding: 0;
  color: var(--fg);
  background-color: var(--bg);
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--links);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--links-hover);
  text-decoration: underline;
}

/* ==========================================================================
   Layout Structure
   ========================================================================== */

.page-wrapper {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  margin-left: var(--sidebar-width);
  transition: margin-left var(--transition-fast);
}

body.sidebar-hidden .page-wrapper {
  margin-left: 0;
}

.content-container {
  display: flex;
  flex-direction: column;
  flex: 1;
  max-width: var(--content-max-width);
  width: 100%;
  margin: 0 auto;
  padding: 2.5rem 1.5rem 4rem;
  position: relative;
}

/* ==========================================================================
   Sidebar Navigation
   ========================================================================== */

.sidebar {
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  width: var(--sidebar-width);
  background-color: var(--sidebar-bg);
  border-right: 1px solid var(--sidebar-border);
  display: flex;
  flex-direction: column;
  z-index: 100;
  transition: transform var(--transition-fast);
}

body.sidebar-hidden .sidebar {
  transform: translateX(calc(-1 * var(--sidebar-width)));
}

.sidebar-header {
  height: var(--menu-bar-height);
  display: flex;
  align-items: center;
  padding: 0 1.25rem;
  border-bottom: 1px solid var(--sidebar-border);
}

.sidebar-brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--sidebar-fg);
  font-weight: 700;
  font-size: 1.1rem;
  text-decoration: none;
}

.sidebar-brand:hover {
  color: var(--icons-hover);
  text-decoration: none;
}

.sidebar-scrollbox {
  flex: 1;
  overflow-y: auto;
  padding: 1rem 0.75rem;
}

.sidebar-scrollbox::-webkit-scrollbar {
  width: 6px;
}

.sidebar-scrollbox::-webkit-scrollbar-thumb {
  background-color: var(--scrollbar);
  border-radius: var(--radius-sm);
}

.chapter-group {
  margin-bottom: 1.2rem;
}

.chapter-group summary {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--sidebar-group);
  padding: 0.35rem 0.5rem;
  cursor: pointer;
  user-select: none;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-radius: var(--radius-sm);
  transition: color var(--transition-fast);
}

.chapter-group summary::-webkit-details-marker {
  display: none;
}

.chapter-group summary:hover {
  color: var(--sidebar-fg);
}

.chapter-group ul {
  list-style: none;
  margin: 0.25rem 0 0;
  padding: 0 0 0 0.5rem;
}

.chapter-group li {
  margin: 0.15rem 0;
}

.chapter-group a {
  display: block;
  padding: 0.35rem 0.65rem;
  font-size: 0.9rem;
  color: var(--sidebar-fg);
  border-radius: var(--radius-sm);
  border-left: 3px solid transparent;
  transition: background var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast);
}

.chapter-group a:hover {
  background-color: var(--sidebar-hover);
  color: var(--icons-hover);
  text-decoration: none;
}

.chapter-group a[aria-current="page"] {
  background-color: var(--sidebar-active-bg);
  color: var(--sidebar-active);
  border-left-color: var(--sidebar-active);
  font-weight: 600;
}

/* ==========================================================================
   Header Menu Bar
   ========================================================================== */

.menu-bar {
  height: var(--menu-bar-height);
  background-color: var(--menu-bar-bg);
  border-bottom: 1px solid var(--menu-bar-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 1.25rem;
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(8px);
}

.left-buttons, .right-buttons {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.menu-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--fg-heading);
  margin: 0;
  white-space: nowrap;
}

.icon-button {
  background: transparent;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  color: var(--icons);
  padding: 0.4rem 0.5rem;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: background var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast);
}

.icon-button:hover {
  color: var(--icons-hover);
  background-color: var(--sidebar-hover);
  border-color: var(--menu-bar-border);
}

/* Theme Dropdown */
.theme-wrapper {
  position: relative;
}

.theme-popup {
  position: absolute;
  top: calc(100% + 6px);
  left: 0;
  background-color: var(--theme-popup-bg);
  border: 1px solid var(--theme-popup-border);
  border-radius: var(--radius-md);
  padding: 0.35rem 0;
  margin: 0;
  list-style: none;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.35);
  z-index: 150;
  min-width: 120px;
}

.theme-option {
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  padding: 0.45rem 1rem;
  font-size: 0.875rem;
  color: var(--fg);
  cursor: pointer;
  transition: background var(--transition-fast);
}

.theme-option:hover {
  background-color: var(--sidebar-hover);
  color: var(--fg-heading);
}

.theme-option.active {
  color: var(--sidebar-active);
  font-weight: 600;
}

/* ==========================================================================
   Search Modal / Overlay
   ========================================================================== */

.search-wrapper {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.55);
  backdrop-filter: blur(4px);
  display: flex;
  justify-content: center;
  align-items: flex-start;
  padding-top: 10vh;
  z-index: 200;
}

.search-wrapper.hidden {
  display: none;
}

.searchbar-outer {
  width: 100%;
  max-width: 600px;
  background-color: var(--search-popup-bg);
  border: 1px solid var(--search-popup-border);
  border-radius: var(--radius-lg);
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.45);
  overflow: hidden;
}

.search-input-box {
  display: flex;
  align-items: center;
  padding: 0.75rem 1rem;
  gap: 0.75rem;
  border-bottom: 1px solid var(--search-popup-border);
}

.search-icon {
  color: var(--icons);
  flex-shrink: 0;
}

.search-input-box input {
  flex: 1;
  background: transparent;
  border: none;
  color: var(--searchbar-fg);
  font-size: 1rem;
  outline: none;
}

.search-hint {
  font-size: 0.75rem;
  padding: 0.2rem 0.45rem;
  background: var(--code-bg);
  border: 1px solid var(--menu-bar-border);
  border-radius: var(--radius-sm);
  color: var(--sidebar-group);
}

.search-results {
  max-height: 50vh;
  overflow-y: auto;
  padding: 0.5rem 0;
}

.search-results a {
  display: block;
  padding: 0.65rem 1.25rem;
  color: var(--fg);
  text-decoration: none;
  font-size: 0.95rem;
  border-left: 3px solid transparent;
  transition: background var(--transition-fast);
}

.search-results a:hover,
.search-results a[aria-selected="true"] {
  background-color: var(--sidebar-hover);
  border-left-color: var(--sidebar-active);
  color: var(--fg-heading);
}

/* ==========================================================================
   Main Content Typography & Elements
   ========================================================================== */

.chapter {
  min-height: 400px;
  outline: none;
}

.chapter:focus,
.chapter:focus-visible {
  outline: none;
}

.chapter h1 {
  font-size: 2.2rem;
  font-weight: 700;
  color: var(--fg-heading);
  border-bottom: 1px solid var(--table-border);
  padding-bottom: 0.5rem;
  margin-top: 0;
  margin-bottom: 1.5rem;
}

.chapter h2 {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--fg-heading);
  margin-top: 2.5rem;
  margin-bottom: 1rem;
  border-bottom: 1px solid var(--code-border);
  padding-bottom: 0.35rem;
}

.chapter h3 {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--fg-heading);
  margin-top: 1.8rem;
  margin-bottom: 0.75rem;
}

.chapter p {
  margin: 1.1rem 0;
}

.chapter ul, .chapter ol {
  padding-left: 1.5rem;
  margin: 1rem 0;
}

.chapter li {
  margin: 0.4rem 0;
}

.chapter blockquote {
  margin: 1.5rem 0;
  padding: 0.75rem 1.25rem;
  background-color: var(--quote-bg);
  border-left: 4px solid var(--quote-border);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

.chapter blockquote p {
  margin: 0.4rem 0;
}

.chapter hr {
  border: none;
  border-top: 1px solid var(--table-border);
  margin: 2.5rem 0;
}

.chapter img {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-md);
  border: 1px solid var(--code-border);
  margin: 1.5rem 0;
}

/* Tables */
.table-wrapper {
  overflow-x: auto;
  margin: 1.5rem 0;
  border: 1px solid var(--table-border);
  border-radius: var(--radius-md);
}

.chapter table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 0.925rem;
}

.chapter th {
  background-color: var(--table-header-bg);
  color: var(--fg-heading);
  font-weight: 600;
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--table-border);
}

.chapter td {
  padding: 0.65rem 1rem;
  border-bottom: 1px solid var(--table-border);
}

.chapter tr:nth-child(even) td {
  background-color: var(--table-alt-bg);
}

.chapter tr:last-child td {
  border-bottom: none;
}

/* Inline Code */
code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background-color: var(--inline-code-bg);
  color: var(--inline-code-fg);
  padding: 0.15em 0.4em;
  border-radius: var(--radius-sm);
}

/* ==========================================================================
   Code Blocks & Syntax Highlighting
   ========================================================================== */

pre {
  position: relative;
  background-color: var(--code-bg);
  border: 1px solid var(--code-border);
  border-radius: var(--radius-md);
  padding: 1.25rem 1rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-family: var(--font-mono);
  font-size: 0.875rem;
  line-height: 1.6;
}

pre code {
  background: transparent;
  color: var(--code-fg);
  padding: 0;
  border-radius: 0;
  font-size: 1em;
  display: block;
}

/* Copy Button */
.code-header-bar {
  position: absolute;
  top: 0.4rem;
  right: 0.5rem;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  z-index: 10;
  opacity: 0;
  transition: opacity var(--transition-fast);
}

pre:hover .code-header-bar {
  opacity: 1;
}

.copy-code-btn, .toggle-boring-btn {
  background-color: var(--code-header-bg);
  border: 1px solid var(--code-border);
  border-radius: var(--radius-sm);
  color: var(--icons);
  font-size: 0.75rem;
  padding: 0.25rem 0.55rem;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  transition: background var(--transition-fast), color var(--transition-fast);
}

.copy-code-btn:hover, .toggle-boring-btn:hover {
  background-color: var(--sidebar-hover);
  color: var(--icons-hover);
}

.copy-code-btn.copied {
  color: #10b981;
  border-color: #10b981;
}

/* Doctest Hidden Lines */
.boring {
  display: none;
}

pre.show-boring .boring {
  display: inline;
  opacity: 0.5;
}

/* Syntax Highlighting Colors (hl-*) */
.hljs-keyword, .hl-kw { color: #f43f5e; font-weight: 600; }
.hljs-type, .hl-type { color: #38bdf8; font-weight: 600; }
.hljs-string, .hl-str { color: #4ade80; }
.hljs-number, .hl-num { color: #fb923c; }
.hljs-comment, .hl-cmt { color: #94a3b8; font-style: italic; }
.hljs-meta, .hl-meta { color: #c084fc; }
.hljs-symbol, .hl-sym { color: #e879f9; }
.hljs-function, .hl-fn { color: #60a5fa; }
.hljs-macro, .hl-macro { color: #f59e0b; font-weight: 600; }

html.light .hljs-keyword, html.light .hl-kw { color: #d70025; }
html.light .hljs-type, html.light .hl-type { color: #0030f2; }
html.light .hljs-string, html.light .hl-str { color: #008200; }
html.light .hljs-number, html.light .hl-num { color: #b21e00; }
html.light .hljs-comment, html.light .hl-cmt { color: #6e7781; }
html.light .hljs-meta, html.light .hl-meta { color: #9d00ec; }
html.light .hljs-macro, html.light .hl-macro { color: #b21e00; }

html.rust .hljs-keyword, html.rust .hl-kw { color: #8b3a1a; font-weight: 600; }
html.rust .hljs-type, html.rust .hl-type { color: #20609f; }
html.rust .hljs-string, html.rust .hl-str { color: #2d7335; }
html.rust .hljs-number, html.rust .hl-num { color: #a34e00; }
html.rust .hljs-comment, html.rust .hl-cmt { color: #736d64; }
html.rust .hljs-meta, html.rust .hl-meta { color: #6a3d9a; }
html.rust .hljs-macro, html.rust .hl-macro { color: #b35917; }

/* ==========================================================================
   Compilation Output, Terminal & Diagnostic Blocks
   ========================================================================== */

pre.terminal-block, pre.diag-block {
  background-color: var(--terminal-bg);
  border-left: 4px solid var(--sidebar-active);
  padding-top: 2rem;
}

pre.diag-error-block {
  border-left-color: #ef4444;
}

pre.diag-warn-block {
  border-left-color: #f59e0b;
}

.terminal-badge {
  position: absolute;
  top: 0;
  left: 0;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 0.2rem 0.65rem;
  background-color: var(--sidebar-hover);
  color: var(--icons);
  border-bottom-right-radius: var(--radius-sm);
}

.diag-error-block .terminal-badge {
  background-color: rgba(239, 68, 68, 0.2);
  color: #ef4444;
}

.diag-warn-block .terminal-badge {
  background-color: rgba(245, 158, 11, 0.2);
  color: #f59e0b;
}

/* Diagnostic Token Highlighting */
.diag-err { color: #ef4444; font-weight: 700; }
.diag-warn { color: #f59e0b; font-weight: 700; }
.diag-loc { color: #38bdf8; font-weight: 600; }
.diag-pipe { color: #64748b; }
.diag-help { color: #10b981; font-weight: 600; }
.test-ok { color: #22c55e; font-weight: 600; }
.test-fail { color: #ef4444; font-weight: 700; }
.diag-verb { color: #38bdf8; font-weight: 600; }

/* ==========================================================================
   Navigation (Floating Wide Side Arrows & Footer Cards)
   ========================================================================== */

.nav-wide-wrapper {
  position: fixed;
  top: var(--menu-bar-height);
  bottom: 0;
  left: var(--sidebar-width);
  right: 0;
  pointer-events: none;
  z-index: 20;
  transition: left var(--transition-fast);
}

body.sidebar-hidden .nav-wide-wrapper {
  left: 0;
}

.nav-chapters {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 68px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--icons);
  background: transparent;
  pointer-events: auto;
  opacity: 0.3;
  cursor: pointer;
  text-decoration: none;
  transition: opacity 0.2s cubic-bezier(0.4, 0, 0.2, 1),
              color 0.2s cubic-bezier(0.4, 0, 0.2, 1),
              background 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.nav-chapters svg {
  width: 32px;
  height: 32px;
  transition: transform 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.nav-chapters:hover {
  opacity: 1;
  color: var(--icons-hover);
  text-decoration: none;
}

.nav-chapters.previous {
  left: 0;
}

.nav-chapters.previous:hover {
  background: linear-gradient(to right, rgba(0, 0, 0, 0.18), transparent);
}

.nav-chapters.previous:hover svg {
  transform: translateX(-4px);
}

.nav-chapters.next {
  right: 0;
}

.nav-chapters.next:hover {
  background: linear-gradient(to left, rgba(0, 0, 0, 0.18), transparent);
}

.nav-chapters.next:hover svg {
  transform: translateX(4px);
}

.nav-chapters.hidden,
.nav-chapters[hidden] {
  display: none !important;
}

@media (max-width: 900px) {
  .nav-wide-wrapper {
    display: none;
  }
}

/* Footer Card Navigation */
.chapter-nav {
  margin-top: 4rem;
  padding-top: 2rem;
  border-top: 1px solid var(--table-border);
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.25rem;
}

.nav-footer-btn {
  display: flex;
  flex-direction: column;
  padding: 1.15rem 1.4rem;
  background-color: var(--code-bg);
  border: 1px solid var(--code-border);
  border-radius: var(--radius-md);
  color: var(--fg);
  text-decoration: none;
  transition: transform var(--transition-fast),
              border-color var(--transition-fast),
              background-color var(--transition-fast),
              box-shadow var(--transition-fast);
}

.nav-footer-btn:hover {
  background-color: var(--sidebar-hover);
  border-color: var(--sidebar-active);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
  color: var(--fg-heading);
  text-decoration: none;
}

.nav-footer-btn .nav-direction {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--sidebar-group);
  margin-bottom: 0.35rem;
}

.nav-footer-btn .nav-title {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--fg-heading);
  line-height: 1.4;
}

.nav-footer-btn.next {
  text-align: right;
  align-items: flex-end;
}

.nav-footer-btn.previous {
  text-align: left;
  align-items: flex-start;
}

.nav-footer-btn[hidden] {
  display: none !important;
}

/* ==========================================================================
   Mobile & Responsive Adjustments
   ========================================================================== */

@media (max-width: 900px) {
  :root {
    --sidebar-width: 260px;
  }

  .page-wrapper {
    margin-left: 0;
  }

  .sidebar {
    transform: translateX(calc(-1 * var(--sidebar-width)));
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.4);
  }

  body.sidebar-open .sidebar {
    transform: translateX(0);
  }

  .menu-title {
    font-size: 0.95rem;
  }

  .content-container {
    padding: 1.5rem 1rem 3rem;
  }
}

/* Skip link */
.skip-link {
  position: absolute;
  top: -4rem;
  left: 0.5rem;
  background: var(--sidebar-active);
  color: #ffffff;
  padding: 0.5rem 1rem;
  border-radius: var(--radius-sm);
  z-index: 1000;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 0.5rem;
}