/* ================================================================
   Building at Scale with AI Coding Agents
   Shared Stylesheet
   ================================================================ */

:root {
  /* Colors */
  --bg: #FAFAF8;
  --bg-sidebar: #F3F2EE;
  --bg-hero: #1C1917;
  --text: #1A1A1A;
  --text-secondary: #5C5C5C;
  --text-muted: #8A8A8A;
  --text-inverse: #F5F5F0;
  --accent: #B44D2D;
  --accent-light: #F4E8E3;
  --accent-dark: #8C3A20;
  --accent-hover: #C45A38;
  --border: #E4E2DD;
  --border-strong: #CCC9C1;

  /* Code */
  --code-bg: #1E1E2E;
  --code-text: #CDD6F4;
  --code-comment: #6C7086;
  --code-keyword: #CBA6F7;
  --code-string: #A6E3A1;
  --code-number: #FAB387;
  --code-fn: #89B4FA;

  /* Callouts */
  --principle-bg: #F4E8E3;
  --principle-border: #B44D2D;
  --principle-text: #8C3A20;
  --warning-bg: #FEF7E7;
  --warning-border: #D4A017;
  --warning-text: #7A5C00;
  --tip-bg: #E8F4F0;
  --tip-border: #2D8A6F;
  --tip-text: #1A5C47;
  --research-bg: #EDE8F5;
  --research-border: #6B5B95;
  --research-text: #4A3D6E;

  /* Diagram */
  --diagram-bg: #F8F7F5;
  --diagram-border: #E4E2DD;
  --diagram-node: #FFFFFF;
  --diagram-node-border: #CCC9C1;
  --diagram-arrow: #8A8A8A;
  --diagram-highlight: #B44D2D;

  /* Layout */
  --sidebar-w: 260px;
  --content-max: 740px;

  /* Typography */
  --font-body: 'DM Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-heading: 'Newsreader', 'Georgia', 'Times New Roman', serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', 'Fira Code', monospace;
}

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

* { margin: 0; padding: 0; box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  font-size: 16px;
  scroll-padding-top: 2rem;
}

body {
  font-family: var(--font-body);
  color: var(--text);
  background: var(--bg);
  line-height: 1.72;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ================================================================
   Progress Bar
   ================================================================ */

.progress-bar {
  position: fixed;
  top: 0;
  left: var(--sidebar-w);
  right: 0;
  height: 2px;
  background: var(--border);
  z-index: 200;
}

.progress-bar .fill {
  height: 100%;
  background: var(--accent);
  width: 0%;
  transition: width 0.1s;
}

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

.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width: var(--sidebar-w);
  background: var(--bg-sidebar);
  border-right: 1px solid var(--border);
  overflow-y: auto;
  padding: 1.5rem 0;
  z-index: 100;
  scrollbar-width: thin;
  scrollbar-color: var(--border-strong) transparent;
}

.sidebar-brand {
  padding: 0 1.25rem;
  margin-bottom: 1.5rem;
}

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

.sidebar-title {
  font-family: var(--font-heading);
  font-size: 0.88rem;
  font-weight: 600;
  line-height: 1.3;
  margin-bottom: 0.15rem;
}

.sidebar-subtitle {
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
}

.sidebar nav { padding: 0; }

.nav-group { margin-bottom: 0.15rem; }

.nav-group-label {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  padding: 0.65rem 1.25rem 0.25rem;
}

.sidebar a {
  display: block;
  padding: 0.25rem 1.25rem;
  font-size: 0.8rem;
  color: var(--text-secondary);
  text-decoration: none;
  border-left: 2px solid transparent;
  transition: all 0.15s ease;
  line-height: 1.4;
}

.sidebar a:hover {
  color: var(--text);
  background: rgba(0, 0, 0, 0.03);
}

.sidebar a.active {
  color: var(--accent);
  border-left-color: var(--accent);
  font-weight: 500;
  background: var(--accent-light);
}

.sidebar a.current-page {
  color: var(--text);
  font-weight: 600;
  border-left-color: var(--text);
  background: rgba(0, 0, 0, 0.05);
}

.sidebar .nav-divider {
  height: 1px;
  background: var(--border);
  margin: 0.5rem 1.25rem;
}

/* ================================================================
   Main Content Area
   ================================================================ */

.main {
  margin-left: var(--sidebar-w);
  min-height: 100vh;
}

.content {
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 3rem 2rem 6rem;
}

/* ================================================================
   Page Hero
   ================================================================ */

.hero {
  padding: 4rem 0 2.5rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 2.5rem;
}

.hero-part-num {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 0.5rem;
}

.hero h1 {
  font-family: var(--font-heading);
  font-size: 2.4rem;
  font-weight: 700;
  line-height: 1.15;
  color: var(--text);
  margin-bottom: 0.75rem;
  letter-spacing: -0.02em;
}

.hero .lead {
  font-size: 1.1rem;
  color: var(--text-secondary);
  line-height: 1.65;
  max-width: 600px;
}

.hero .reading-time {
  margin-top: 1rem;
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* Index page hero (dark) */
.hero-dark {
  background: var(--bg-hero);
  color: var(--text-inverse);
  padding: 5rem 2rem 4rem;
  margin-left: var(--sidebar-w);
  border-bottom: none;
}

.hero-dark h1 {
  color: var(--text-inverse);
  font-size: 2.8rem;
  max-width: var(--content-max);
  margin: 0 auto 1rem;
}

.hero-dark .lead {
  color: rgba(245, 245, 240, 0.75);
  max-width: var(--content-max);
  margin: 0 auto;
}

.hero-dark .reading-time {
  color: rgba(245, 245, 240, 0.5);
  max-width: var(--content-max);
  margin: 1rem auto 0;
}

/* ================================================================
   Typography
   ================================================================ */

h2 {
  font-family: var(--font-heading);
  font-size: 1.75rem;
  font-weight: 600;
  margin: 3rem 0 0.75rem;
  padding-top: 1.75rem;
  border-top: 1px solid var(--border);
  letter-spacing: -0.01em;
  line-height: 1.25;
}

h2:first-of-type,
.hero + h2 {
  border-top: none;
  padding-top: 0;
  margin-top: 0;
}

h3 {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  font-weight: 600;
  margin: 2.25rem 0 0.6rem;
  line-height: 1.3;
}

h4 {
  font-family: var(--font-body);
  font-size: 0.95rem;
  font-weight: 700;
  margin: 1.5rem 0 0.4rem;
  letter-spacing: 0.01em;
}

p { margin-bottom: 1rem; }
strong { font-weight: 600; }
em { font-style: italic; }

a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-hover); text-decoration: underline; }

/* ================================================================
   Lists
   ================================================================ */

ul, ol {
  margin: 0 0 1rem 1.5rem;
}

li { margin-bottom: 0.3rem; }
li ul, li ol { margin-top: 0.3rem; margin-bottom: 0; }

/* ================================================================
   Inline Code & Code Blocks
   ================================================================ */

code {
  font-family: var(--font-mono);
  font-size: 0.84em;
  background: rgba(0, 0, 0, 0.05);
  padding: 0.12em 0.35em;
  border-radius: 3px;
}

pre {
  background: var(--code-bg);
  color: var(--code-text);
  padding: 1.25rem 1.5rem;
  border-radius: 8px;
  overflow-x: auto;
  margin: 1rem 0 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.6;
}

pre code {
  background: none;
  padding: 0;
  font-size: inherit;
  color: inherit;
}

/* Syntax highlighting classes */
.kw { color: var(--code-keyword); }
.st { color: var(--code-string); }
.cm { color: var(--code-comment); }
.nu { color: var(--code-number); }
.fn { color: var(--code-fn); }

/* ================================================================
   Tables
   ================================================================ */

table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0 1.5rem;
  font-size: 0.86rem;
}

th {
  text-align: left;
  font-weight: 600;
  padding: 0.55rem 0.7rem;
  border-bottom: 2px solid var(--border-strong);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-secondary);
}

td {
  padding: 0.5rem 0.7rem;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

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

/* ================================================================
   Callout Boxes
   ================================================================ */

.callout {
  padding: 1rem 1.2rem;
  border-radius: 6px;
  margin: 1.25rem 0;
  font-size: 0.9rem;
  line-height: 1.6;
}

.callout p:last-child { margin-bottom: 0; }

.callout-principle {
  background: var(--principle-bg);
  border-left: 3px solid var(--principle-border);
}
.callout-principle strong { color: var(--principle-text); }

.callout-warning {
  background: var(--warning-bg);
  border-left: 3px solid var(--warning-border);
}
.callout-warning strong { color: var(--warning-text); }

.callout-tip {
  background: var(--tip-bg);
  border-left: 3px solid var(--tip-border);
}
.callout-tip strong { color: var(--tip-text); }

.callout-research {
  background: var(--research-bg);
  border-left: 3px solid var(--research-border);
}
.callout-research strong { color: var(--research-text); }

/* ================================================================
   Diagrams (ASCII art in styled containers)
   ================================================================ */

.diagram {
  background: var(--diagram-bg);
  border: 1px solid var(--diagram-border);
  padding: 1.5rem 2rem;
  border-radius: 8px;
  margin: 1.5rem 0;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  line-height: 1.5;
  white-space: pre;
  overflow-x: auto;
  color: var(--text);
}

/* SVG diagram containers */
.diagram-visual {
  background: var(--diagram-bg);
  border: 1px solid var(--diagram-border);
  border-radius: 8px;
  margin: 1.5rem 0;
  padding: 1.5rem;
  text-align: center;
  overflow-x: auto;
}

.diagram-visual svg {
  max-width: 100%;
  height: auto;
}

.diagram-caption {
  font-size: 0.78rem;
  color: var(--text-muted);
  text-align: center;
  margin-top: 0.5rem;
  font-style: italic;
}

/* ================================================================
   Linear Example Blocks
   ================================================================ */

.example-block {
  background: #F8F7F5;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.25rem 1.5rem;
  margin: 1.25rem 0;
  font-size: 0.88rem;
}

.example-block-header {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent);
  margin-bottom: 0.6rem;
  font-weight: 600;
}

.example-block h4 { margin-top: 0.75rem; }
.example-block h4:first-of-type { margin-top: 0; }
.example-block p:last-child { margin-bottom: 0; }

/* ================================================================
   Template Blocks (Appendix)
   ================================================================ */

.template-block {
  background: #F8F7F5;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.5rem;
  margin: 1rem 0 1.5rem;
  font-size: 0.86rem;
}

.template-block h4 {
  margin-top: 0;
  font-size: 0.9rem;
}

/* ================================================================
   Page Navigation (prev/next)
   ================================================================ */

.page-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 4rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
  gap: 1rem;
}

.page-nav a {
  display: block;
  padding: 1rem 1.25rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  text-decoration: none;
  color: var(--text);
  flex: 1;
  max-width: 48%;
  transition: border-color 0.15s, background 0.15s;
}

.page-nav a:hover {
  border-color: var(--accent);
  background: var(--accent-light);
  text-decoration: none;
}

.page-nav .nav-label {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin-bottom: 0.25rem;
}

.page-nav .nav-title {
  font-weight: 600;
  font-size: 0.9rem;
}

.page-nav .next { text-align: right; margin-left: auto; }

/* ================================================================
   Index Page Cards
   ================================================================ */

.part-cards {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.75rem;
  margin: 1.5rem 0;
}

.part-card {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  padding: 1rem 1.25rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  text-decoration: none;
  color: var(--text);
  transition: border-color 0.15s, background 0.15s, transform 0.15s;
}

.part-card:hover {
  border-color: var(--accent);
  background: var(--accent-light);
  text-decoration: none;
  transform: translateY(-1px);
}

.part-num {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--accent);
  font-weight: 600;
  flex-shrink: 0;
  padding-top: 0.15rem;
}

.part-card-title {
  font-weight: 600;
  font-size: 0.92rem;
  margin-bottom: 0.2rem;
}

.part-card-desc {
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* ================================================================
   Footer
   ================================================================ */

.page-footer {
  margin-top: 4rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* ================================================================
   Section Numbers
   ================================================================ */

.section-num {
  font-family: var(--font-mono);
  font-size: 0.72em;
  color: var(--accent);
  margin-right: 0.4rem;
}

/* ================================================================
   Responsive
   ================================================================ */

@media (max-width: 960px) {
  .sidebar { display: none; }
  .main { margin-left: 0; }
  .hero-dark { margin-left: 0; padding: 3rem 1.25rem 2.5rem; }
  .hero-dark h1 { font-size: 2rem; }
  .content { padding: 2rem 1.25rem 4rem; }
  .hero h1 { font-size: 1.9rem; }
  h2 { font-size: 1.45rem; }
  pre { font-size: 0.75rem; padding: 1rem; }
  .progress-bar { left: 0; }
  .page-nav { flex-direction: column; }
  .page-nav a { max-width: 100%; }
}

/* ================================================================
   Print
   ================================================================ */

@media print {
  .sidebar, .progress-bar, .page-nav { display: none; }
  .main { margin-left: 0; }
  .hero-dark { margin-left: 0; background: white; color: black; }
  .hero-dark h1 { color: black; }
  body { font-size: 11pt; }
}