/* ============================================
   The Monograph — OperationsPAI Design System
   ============================================ */

/* --- Design Tokens --- */
:root {
  --bg-primary: #FDFBF7;
  --bg-secondary: #F5F0E8;
  --bg-accent: #EDE6D8;
  --text-primary: #2C2825;
  --text-secondary: #6B6560;
  --text-muted: #9C9590;
  --accent: #B8860B;
  --accent-light: #D4A84B;
  --border: #E0D8CC;
  --code-bg: #F0EBE1;

  --font-heading: 'Playfair Display', Georgia, 'Times New Roman', serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;

  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  --space-3xl: 64px;

  --max-width: 1200px;
  --content-width: 65ch;
  --content-wide: 75ch;
}

/* --- Reset --- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-body);
  font-weight: 400;
  line-height: 1.7;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--accent-light);
}

a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 2px;
}

/* --- Typography — Generic Markdown Rendering --- */

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.3;
  color: var(--text-primary);
}

h1 { font-size: 2.441rem; margin: var(--space-3xl) 0 var(--space-lg); }
h2 { font-size: 1.953rem; margin: var(--space-2xl) 0 var(--space-md); }
h3 { font-size: 1.563rem; margin: var(--space-xl) 0 var(--space-md); }
h4 { font-size: 1.25rem;  margin: var(--space-lg) 0 var(--space-sm); }
h5 { font-size: 1.1rem;   margin: var(--space-lg) 0 var(--space-sm); }
h6 { font-size: 1rem;     margin: var(--space-lg) 0 var(--space-sm); font-style: italic; }

/* First heading on page — no top margin */
h1:first-child, h2:first-child, h3:first-child {
  margin-top: 0;
}

p {
  margin: 0 0 var(--space-md);
}

/* --- Lists --- */
ul, ol {
  margin: 0 0 var(--space-md);
  padding-left: var(--space-lg);
}

li {
  margin-bottom: var(--space-xs);
}

li > ul, li > ol {
  margin-top: var(--space-xs);
  margin-bottom: 0;
}

/* Task lists (GitHub Flavored Markdown) */
ul.task-list, .task-list {
  list-style: none;
  padding-left: 0;
}

.task-list li {
  position: relative;
  padding-left: var(--space-lg);
}

.task-list input[type="checkbox"] {
  position: absolute;
  left: 0;
  top: 0.35em;
  accent-color: var(--accent);
}

/* --- Blockquotes --- */
blockquote {
  margin: var(--space-lg) 0;
  padding: var(--space-md) var(--space-lg);
  border-left: 3px solid var(--accent-light);
  background: transparent;
  font-family: var(--font-heading);
  font-style: italic;
  color: var(--text-secondary);
}

blockquote p:last-child {
  margin-bottom: 0;
}

blockquote blockquote {
  margin-top: var(--space-md);
}

/* --- Code --- */
code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: var(--code-bg);
  padding: 2px 6px;
  border-radius: 3px;
  color: var(--text-primary);
}

pre {
  margin: var(--space-lg) 0;
  padding: var(--space-md) var(--space-lg);
  background: var(--code-bg);
  border-left: 3px solid var(--accent);
  border-radius: 4px;
  overflow-x: auto;
  line-height: 1.5;
}

pre code {
  background: none;
  padding: 0;
  border-radius: 0;
  font-size: 0.85rem;
}

/* --- Tables --- */
table {
  width: 100%;
  margin: var(--space-lg) 0;
  border-collapse: collapse;
  font-size: 0.95rem;
}

thead {
  border-bottom: 2px solid var(--border);
}

th {
  font-family: var(--font-heading);
  font-weight: 600;
  text-align: left;
  padding: var(--space-sm) var(--space-md);
  color: var(--text-primary);
}

td {
  padding: var(--space-sm) var(--space-md);
  border-bottom: 1px solid var(--border);
}

tbody tr:hover {
  background: var(--bg-secondary);
}

/* --- Horizontal Rule --- */
hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: var(--space-2xl) 0;
}

/* --- Images in markdown --- */
.content img {
  border-radius: 6px;
  border: 1px solid var(--border);
  margin: var(--space-lg) 0;
}

/* --- Definition lists --- */
dl {
  margin: 0 0 var(--space-md);
}

dt {
  font-weight: 600;
  margin-top: var(--space-md);
}

dd {
  margin-left: var(--space-lg);
  color: var(--text-secondary);
}

/* --- Keyboard / abbreviations --- */
kbd {
  font-family: var(--font-mono);
  font-size: 0.85em;
  padding: 2px 6px;
  border: 1px solid var(--border);
  border-radius: 3px;
  background: var(--bg-secondary);
  box-shadow: 0 1px 0 var(--border);
}

abbr[title] {
  text-decoration: underline dotted var(--text-muted);
  cursor: help;
}

/* --- Details / Summary --- */
details {
  margin: var(--space-md) 0;
  padding: var(--space-md);
  background: var(--bg-secondary);
  border-radius: 6px;
  border: 1px solid var(--border);
}

summary {
  cursor: pointer;
  font-weight: 500;
  color: var(--text-primary);
}

details[open] summary {
  margin-bottom: var(--space-md);
}

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

/* --- Skip to content (accessibility) --- */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-md);
  padding: var(--space-sm) var(--space-md);
  background: var(--accent);
  color: var(--bg-primary);
  border-radius: 0 0 4px 4px;
  z-index: 1000;
  font-size: 0.875rem;
  text-decoration: none;
}

.skip-link:focus {
  top: 0;
}

/* --- Site Header --- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg-primary);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-md) var(--space-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-logo {
  font-family: var(--font-heading);
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
}

.site-logo:hover {
  color: var(--accent);
}

.site-nav {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}

.site-nav a {
  font-family: var(--font-body);
  font-weight: 500;
  font-size: 0.9rem;
  color: var(--text-secondary);
  text-decoration: none;
  position: relative;
  padding-bottom: 4px;
}

.site-nav a:hover {
  color: var(--text-primary);
}

.site-nav a.active {
  color: var(--text-primary);
}

.site-nav a.active::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 50%;
  transform: translateX(-50%);
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--accent);
}

/* --- Mobile Nav (CSS-only) --- */
.nav-toggle {
  display: none;
}

.nav-toggle-label {
  display: none;
  cursor: pointer;
  width: 28px;
  height: 20px;
  position: relative;
  z-index: 200;
}

.nav-toggle-label span,
.nav-toggle-label span::before,
.nav-toggle-label span::after {
  display: block;
  width: 100%;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  position: absolute;
  transition: all 0.3s ease;
}

.nav-toggle-label span { top: 50%; transform: translateY(-50%); }
.nav-toggle-label span::before { content: ''; top: -8px; }
.nav-toggle-label span::after { content: ''; top: 8px; }

.nav-toggle:checked ~ .nav-toggle-label span { background: transparent; }
.nav-toggle:checked ~ .nav-toggle-label span::before { top: 0; transform: rotate(45deg); }
.nav-toggle:checked ~ .nav-toggle-label span::after { top: 0; transform: rotate(-45deg); }

.nav-toggle:checked ~ .site-nav {
  transform: translateX(0);
}

/* --- Site Footer --- */
.site-footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border);
  margin-top: var(--space-3xl);
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-2xl) var(--space-lg);
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: var(--space-xl);
}

.footer-section h4 {
  font-family: var(--font-heading);
  font-size: 1rem;
  margin: 0 0 var(--space-md);
  color: var(--text-primary);
}

.footer-section p,
.footer-section a {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.footer-section a {
  text-decoration: none;
  display: block;
  margin-bottom: var(--space-xs);
}

.footer-section a:hover {
  color: var(--accent);
}

.footer-bottom {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-md) var(--space-lg);
  border-top: 1px solid var(--border);
  font-size: 0.8rem;
  color: var(--text-muted);
  text-align: center;
}

/* --- Content Container --- */
.content {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: var(--space-2xl) var(--space-lg);
}

.content-wide {
  max-width: var(--content-wide);
  margin: 0 auto;
  padding: var(--space-2xl) var(--space-lg);
}

.content-full {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-2xl) var(--space-lg);
}

/* ============================================
   Components
   ============================================ */

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 12px 24px;
  border-radius: 6px;
  font-family: var(--font-body);
  font-weight: 500;
  font-size: 0.95rem;
  text-decoration: none;
  transition: all 0.2s ease;
  cursor: pointer;
  border: none;
}

.btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.btn-primary {
  background: var(--accent);
  color: var(--bg-primary);
}

.btn-primary:hover {
  background: var(--accent-light);
  color: var(--bg-primary);
}

.btn-ghost {
  background: transparent;
  border: 1px solid var(--accent);
  color: var(--accent);
}

.btn-ghost:hover {
  background: var(--bg-accent);
  color: var(--accent);
}

/* --- Cards --- */
.card {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: var(--space-lg);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.card-icon {
  width: 24px;
  height: 24px;
  color: var(--accent);
  margin-bottom: var(--space-md);
}

.card h3 {
  font-family: var(--font-heading);
  font-size: 1.15rem;
  margin: 0 0 var(--space-sm);
}

.card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin: 0;
}

/* Link card — entire card clickable */
a.card {
  text-decoration: none;
  color: inherit;
  display: block;
}

a.card:hover {
  border-color: var(--accent);
}

a.card h3 {
  color: var(--text-primary);
}

/* --- Grid --- */
.grid {
  display: grid;
  gap: var(--space-lg);
}

.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-auto { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }

/* --- Section helpers --- */
.section {
  padding: var(--space-3xl) 0;
}

.section-label {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  display: block;
  margin-bottom: var(--space-sm);
}

.section-title {
  font-family: var(--font-heading);
  font-size: 1.953rem;
  margin: 0 0 var(--space-md);
}

.section-desc {
  color: var(--text-secondary);
  max-width: var(--content-width);
  margin-bottom: var(--space-xl);
}

.section-header {
  margin-bottom: var(--space-xl);
}

/* --- Contributor Card --- */
.contributor {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-md);
  background: var(--bg-secondary);
  border-radius: 8px;
  border: 1px solid var(--border);
}

.contributor img {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  object-fit: cover;
}

.contributor-name {
  font-weight: 500;
  font-size: 0.95rem;
}

.contributor-role {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.contributor-quote {
  font-style: italic;
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-top: var(--space-xs);
}

/* --- Evolution / Timeline --- */
.timeline {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-lg);
  padding: var(--space-xl) 0;
}

.timeline-step {
  text-align: center;
}

.timeline-number {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--accent);
}

.timeline-label {
  font-family: var(--font-body);
  font-weight: 500;
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-top: var(--space-xs);
}

.timeline-arrow {
  font-size: 1.25rem;
  color: var(--border);
}

/* --- Hero (homepage only) --- */
.hero {
  padding: var(--space-3xl) var(--space-lg);
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: var(--space-3xl);
}

.hero-content {
  flex: 1;
}

.hero-illustration {
  flex: 0 0 auto;
  width: 280px;
  height: 280px;
  color: var(--accent);
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--accent);
  margin-bottom: var(--space-lg);
}

.hero-badge .dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
  animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}

.hero h1 {
  font-size: 2.8rem;
  margin: 0 0 var(--space-md);
  line-height: 1.15;
}

.hero h1 em {
  font-style: normal;
  color: var(--accent);
}

.hero-tagline {
  font-size: 1.15rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: var(--space-xl);
  max-width: 540px;
}

.hero-actions {
  display: flex;
  gap: var(--space-md);
  flex-wrap: wrap;
}

/* ============================================
   Layout: Docs (sidebar + TOC)
   ============================================ */

.docs-layout {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-xl) var(--space-lg);
  display: grid;
  grid-template-columns: 220px 1fr 180px;
  gap: var(--space-xl);
}

.docs-sidebar {
  position: sticky;
  top: 80px;
  max-height: calc(100vh - 100px);
  overflow-y: auto;
}

.docs-sidebar nav a {
  display: block;
  padding: var(--space-xs) var(--space-sm);
  font-size: 0.875rem;
  color: var(--text-secondary);
  text-decoration: none;
  border-radius: 4px;
}

.docs-sidebar nav a:hover {
  color: var(--text-primary);
  background: var(--bg-secondary);
}

.docs-sidebar nav a.active {
  color: var(--accent);
  background: var(--bg-accent);
}

.docs-content {
  max-width: var(--content-width);
  min-width: 0;
}

.docs-toc {
  position: sticky;
  top: 80px;
  max-height: calc(100vh - 100px);
  overflow-y: auto;
  font-size: 0.8rem;
}

.docs-toc a {
  display: block;
  padding: var(--space-xs) 0;
  color: var(--text-muted);
  text-decoration: none;
}

.docs-toc a:hover {
  color: var(--accent);
}

/* Sidebar toggle for mobile */
.docs-sidebar-toggle {
  display: none;
}

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

@media (max-width: 1024px) {
  :root {
    --space-3xl: 48px;
  }

  h1 { font-size: 2rem; }
  h2 { font-size: 1.65rem; }

  .hero h1 { font-size: 2.2rem; }

  .grid-3 { grid-template-columns: repeat(2, 1fr); }

  .docs-layout {
    grid-template-columns: 200px 1fr;
  }

  .docs-toc {
    display: none;
  }

  .hero-illustration {
    width: 200px;
    height: 200px;
  }

  .footer-inner {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 640px) {
  :root {
    --space-2xl: 32px;
    --space-3xl: 40px;
  }

  h1 { font-size: 1.75rem; }
  h2 { font-size: 1.45rem; }
  h3 { font-size: 1.25rem; }

  .hero h1 { font-size: 1.85rem; }

  /* Mobile nav */
  .nav-toggle-label {
    display: block;
  }

  .site-nav {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    width: 260px;
    background: var(--bg-primary);
    border-left: 1px solid var(--border);
    flex-direction: column;
    padding: var(--space-3xl) var(--space-lg) var(--space-lg);
    transform: translateX(100%);
    transition: transform 0.3s ease;
    z-index: 150;
    gap: var(--space-md);
  }

  .site-nav a {
    font-size: 1rem;
    padding: var(--space-sm) 0;
  }

  /* Hero stacked */
  .hero {
    flex-direction: column;
    text-align: center;
    padding: var(--space-2xl) var(--space-md);
  }

  .hero-tagline {
    margin-left: auto;
    margin-right: auto;
  }

  .hero-actions {
    justify-content: center;
  }

  .hero-illustration {
    width: 180px;
    height: 180px;
    order: -1;
  }

  /* Grid single column */
  .grid-2, .grid-3 { grid-template-columns: 1fr; }

  /* Timeline vertical */
  .timeline {
    flex-direction: column;
    gap: var(--space-md);
  }

  .timeline-arrow {
    transform: rotate(90deg);
  }

  /* Docs sidebar */
  .docs-layout {
    grid-template-columns: 1fr;
  }

  .docs-sidebar {
    position: static;
    max-height: none;
    display: none;
  }

  .docs-sidebar-toggle {
    display: block;
    margin-bottom: var(--space-md);
  }

  .docs-sidebar-toggle:checked ~ .docs-sidebar {
    display: block;
  }

  /* Footer single column */
  .footer-inner {
    grid-template-columns: 1fr;
    gap: var(--space-lg);
  }

  .content, .content-wide {
    padding: var(--space-xl) var(--space-md);
  }
}

/* --- Print styles --- */
@media print {
  .site-header, .site-footer, .hero-illustration, .docs-sidebar, .docs-toc {
    display: none;
  }

  body {
    color: #000;
    background: #fff;
  }

  a { color: #000; text-decoration: underline; }
  a[href]::after { content: " (" attr(href) ")"; font-size: 0.8em; }
}