/* ===== Custom Properties ===== */
:root {
  --nvidia-green: #76B900;
  --nvidia-green-dark: #5a8d00;
  --bg: #ffffff;
  --bg-secondary: #f8f9fa;
  --surface: #ffffff;
  --surface-border: #e5e7eb;
  --text-primary: #111827;
  --text-secondary: #4b5563;
  --text-muted: #9ca3af;
  --nav-bg: rgba(255,255,255,0.95);
  --card-bg: #ffffff;
  --card-shadow: 0 1px 4px rgba(0,0,0,0.08), 0 4px 16px rgba(0,0,0,0.05);
  --callout-bg: #f0f7e0;
  --code-bg: #f3f4f6;
  --tooltip-bg: #1f2937;
  --tooltip-text: #f9fafb;
}

[data-theme="dark"] {
  --bg: #0f1117;
  --bg-secondary: #161b22;
  --surface: #1c2128;
  --surface-border: #30363d;
  --text-primary: #e6edf3;
  --text-secondary: #8b949e;
  --text-muted: #6e7681;
  --nav-bg: rgba(15,17,23,0.95);
  --card-bg: #1c2128;
  --card-shadow: 0 1px 4px rgba(0,0,0,0.3), 0 4px 16px rgba(0,0,0,0.2);
  --callout-bg: #1a2509;
  --code-bg: #161b22;
  --tooltip-bg: #e6edf3;
  --tooltip-text: #1f2937;
}

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

html { scroll-behavior: smooth; font-size: 16px; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Inter', 'Segoe UI', sans-serif;
  background: var(--bg);
  color: var(--text-primary);
  line-height: 1.7;
  transition: background 0.2s, color 0.2s;
}

/* ===== Typography ===== */
h1, h2, h3, h4 {
  line-height: 1.2;
  font-weight: 700;
  color: var(--text-primary);
}

h1 { font-size: clamp(2rem, 5vw, 3.5rem); letter-spacing: -0.02em; }
h2 { font-size: clamp(1.5rem, 3vw, 2.25rem); letter-spacing: -0.01em; margin-top: 2.5rem; margin-bottom: 1rem; }
h3 { font-size: 1.25rem; margin-top: 2rem; margin-bottom: 0.75rem; }
h4 { font-size: 1rem; margin-top: 1.5rem; margin-bottom: 0.5rem; }

p { color: var(--text-secondary); margin-bottom: 1.25rem; max-width: 68ch; }

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

code {
  font-family: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;
  background: var(--code-bg);
  padding: 0.15em 0.4em;
  border-radius: 4px;
  font-size: 0.875em;
}

/* ===== Nav ===== */
.site-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--nav-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--surface-border);
}

.nav-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  gap: 1.5rem;
  height: 60px;
}

.nav-logo {
  font-weight: 800;
  font-size: 1.05rem;
  color: var(--text-primary);
  white-space: nowrap;
  text-decoration: none;
}

.nav-logo span { color: var(--nvidia-green); }

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  flex: 1;
}

.nav-dropdown {
  position: relative;
}

/* Invisible hover bridge between button and menu so the menu stays
   open while the mouse crosses the visual gap. Without this, the menu
   disappears before the user can click an item. */
.nav-dropdown::after {
  content: '';
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  height: 14px;
  background: transparent;
  /* Must intercept events so hovering this area counts as hovering
     the dropdown, keeping the menu visible. */
}

.nav-dropdown-btn {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--text-secondary);
  font-size: 0.9rem;
  padding: 0.4rem 0.75rem;
  border-radius: 6px;
  display: flex;
  align-items: center;
  gap: 0.3rem;
  transition: background 0.15s, color 0.15s;
}

.nav-dropdown-btn:hover {
  background: var(--bg-secondary);
  color: var(--text-primary);
}

.nav-dropdown-btn svg { width: 12px; height: 12px; transition: transform 0.2s; }
.nav-dropdown:hover .nav-dropdown-btn svg { transform: rotate(180deg); }

.nav-dropdown-menu {
  position: absolute;
  top: calc(100% + 8px);
  left: 0;
  background: var(--surface);
  border: 1px solid var(--surface-border);
  border-radius: 10px;
  box-shadow: var(--card-shadow);
  min-width: 220px;
  padding: 0.5rem;
  display: none;
  flex-direction: column;
  gap: 0.125rem;
}

.nav-dropdown:hover .nav-dropdown-menu { display: flex; }

.nav-dropdown-menu a {
  color: var(--text-secondary);
  font-size: 0.875rem;
  padding: 0.45rem 0.75rem;
  border-radius: 6px;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
  transition: background 0.1s, color 0.1s;
}

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

.nav-dropdown-menu .menu-num {
  font-size: 0.75rem;
  color: var(--text-muted);
  min-width: 1.5rem;
}

.nav-divider {
  height: 1px;
  background: var(--surface-border);
  margin: 0.35rem 0;
}

.nav-direct-links {
  display: flex;
  gap: 0.5rem;
  margin-left: auto;
}

.nav-direct-links a {
  font-size: 0.875rem;
  color: var(--text-secondary);
  padding: 0.35rem 0.75rem;
  border-radius: 6px;
  text-decoration: none;
  transition: background 0.15s, color 0.15s;
}

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

/* Theme toggle */
.theme-toggle {
  background: none;
  border: 1px solid var(--surface-border);
  border-radius: 8px;
  cursor: pointer;
  padding: 0.35rem 0.6rem;
  display: flex;
  align-items: center;
  color: var(--text-secondary);
  transition: background 0.15s, color 0.15s;
}

.theme-toggle:hover {
  background: var(--bg-secondary);
  color: var(--text-primary);
}

/* Hamburger for mobile */
.nav-hamburger {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  color: var(--text-secondary);
  padding: 0.35rem;
  margin-left: auto;
}

.nav-mobile-menu {
  display: none;
  flex-direction: column;
  background: var(--surface);
  border-top: 1px solid var(--surface-border);
  padding: 1rem 1.5rem;
  gap: 0.25rem;
}

.nav-mobile-menu.open { display: flex; }

.nav-mobile-menu a {
  color: var(--text-secondary);
  font-size: 0.9rem;
  padding: 0.5rem 0;
  text-decoration: none;
  border-bottom: 1px solid var(--surface-border);
}

.nav-mobile-section {
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  padding: 0.75rem 0 0.25rem;
}

/* ===== Footer ===== */
.site-footer {
  border-top: 1px solid var(--surface-border);
  background: var(--bg-secondary);
  padding: 2.5rem 1.5rem;
  margin-top: 5rem;
}

.footer-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
  align-items: center;
  justify-content: space-between;
}

.footer-links {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
}

.footer-links a {
  color: var(--text-muted);
  font-size: 0.875rem;
  text-decoration: none;
}

.footer-links a:hover { color: var(--text-secondary); }

.footer-disclaimer {
  font-size: 0.8rem;
  color: var(--text-muted);
  max-width: 480px;
}

/* ===== Layout ===== */
.page-wrapper {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.content-area {
  max-width: 780px;
}

/* ===== Page Header ===== */
.page-header {
  padding: 4rem 0 2.5rem;
  border-bottom: 1px solid var(--surface-border);
  margin-bottom: 3rem;
}

.page-label {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--nvidia-green);
  margin-bottom: 0.75rem;
}

.page-hook {
  font-size: clamp(1.1rem, 2.5vw, 1.35rem);
  color: var(--text-secondary);
  max-width: 65ch;
  margin-top: 1rem;
}

/* ===== RTX/Spark Callout ===== */
.rtx-callout {
  border-left: 4px solid var(--nvidia-green);
  background: var(--callout-bg);
  border-radius: 0 10px 10px 0;
  padding: 1.5rem 1.75rem;
  margin: 3rem 0;
}

.rtx-callout-label {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--nvidia-green);
  margin-bottom: 0.5rem;
}

.rtx-callout p {
  margin-bottom: 0.75rem;
  color: var(--text-primary);
}

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

/* ===== Cards ===== */
.card {
  background: var(--card-bg);
  border: 1px solid var(--surface-border);
  border-radius: 12px;
  box-shadow: var(--card-shadow);
  padding: 1.5rem;
  transition: box-shadow 0.2s, transform 0.2s;
}

.card:hover {
  box-shadow: 0 4px 20px rgba(0,0,0,0.12);
  transform: translateY(-2px);
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
}

/* Topic card */
.topic-card {
  display: block;
  text-decoration: none;
  color: inherit;
}

.topic-card:hover { text-decoration: none; }

.topic-card .card-num {
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.topic-card h3 {
  font-size: 1.05rem;
  margin: 0 0 0.5rem;
  color: var(--text-primary);
}

.topic-card p {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin: 0;
  max-width: none;
}

/* Section label on index */
.section-label {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--nvidia-green);
  margin: 3rem 0 1rem;
}

/* ===== Macro section cards (homepage) ===== */
.macro-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
  margin: 0 0 5rem;
}

.macro-card {
  display: flex;
  flex-direction: column;
  background: var(--card-bg);
  border: 1px solid var(--surface-border);
  border-radius: 16px;
  box-shadow: var(--card-shadow);
  padding: 2.25rem 2.25rem 2rem;
  text-decoration: none;
  color: inherit;
  position: relative;
  overflow: hidden;
  transition: border-color 0.2s, transform 0.2s, box-shadow 0.2s;
  min-height: 260px;
}

.macro-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 4px;
  background: var(--nvidia-green);
  opacity: 0;
  transition: opacity 0.2s;
}

.macro-card:hover {
  border-color: var(--nvidia-green);
  transform: translateY(-4px);
  box-shadow: 0 10px 30px rgba(0,0,0,0.10);
  text-decoration: none;
}

.macro-card:hover::before { opacity: 1; }

.macro-card-label {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--nvidia-green);
  margin-bottom: 0.4rem;
}

.macro-card-count {
  position: absolute;
  top: 1.75rem;
  right: 2rem;
  font-size: 0.78rem;
  font-weight: 500;
  color: var(--text-muted);
  background: var(--bg-secondary);
  padding: 0.25rem 0.6rem;
  border-radius: 20px;
}

.macro-card h2 {
  font-size: 1.85rem;
  margin: 0 0 0.85rem;
  letter-spacing: -0.015em;
  line-height: 1.15;
  padding-right: 5rem;
}

.macro-card p {
  font-size: 0.95rem;
  color: var(--text-secondary);
  max-width: none;
  margin: 0 0 1.5rem;
  flex: 1;
}

.macro-card-arrow {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--nvidia-green);
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  transition: gap 0.2s;
}

.macro-card:hover .macro-card-arrow { gap: 0.75rem; }

@media (max-width: 720px) {
  .macro-grid { grid-template-columns: 1fr; }
  .macro-card { min-height: 0; padding: 1.75rem; }
  .macro-card h2 { font-size: 1.5rem; padding-right: 4rem; }
}

/* ===== Diagrams ===== */
.diagram-wrap {
  background: var(--bg-secondary);
  border: 1px solid var(--surface-border);
  border-radius: 12px;
  padding: 2rem;
  margin: 2rem 0;
  overflow-x: auto;
}

.diagram-wrap svg { display: block; margin: 0 auto; }

/* ===== Glossary Tooltips ===== */
.gloss {
  border-bottom: 1px dashed var(--nvidia-green);
  cursor: help;
  color: inherit;
  position: relative;
}

.gloss-tooltip {
  position: absolute;
  bottom: calc(100% + 10px);
  left: 50%;
  transform: translateX(-50%) translateY(4px);
  background: var(--tooltip-bg);
  color: var(--tooltip-text);
  font-size: 0.8rem;
  font-weight: 400;
  line-height: 1.55;
  text-align: left;
  padding: 0.75rem 0.9rem;
  border-radius: 10px;
  width: 270px;
  max-width: 78vw;
  pointer-events: none;
  z-index: 200;
  box-shadow: 0 6px 20px rgba(0,0,0,0.25);
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.15s, transform 0.15s, visibility 0.15s;
  white-space: normal;
}

/* Invisible bridge so the cursor can travel from the term down into
   the tooltip without crossing a dead gap that closes it. */
.gloss-tooltip::before {
  content: '';
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  height: 12px;
}

.gloss-tooltip::after {
  content: '';
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  border: 6px solid transparent;
  border-top-color: var(--tooltip-bg);
}

.gloss-tooltip-def { display: block; }

.gloss-tooltip-link {
  display: inline-block;
  margin-top: 0.55rem;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--nvidia-green);
  text-decoration: none;
}

.gloss-tooltip-link:hover { text-decoration: underline; }

.gloss:hover .gloss-tooltip,
.gloss.active .gloss-tooltip {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
  pointer-events: auto;
}

/* ===== Next/Prev Page Nav ===== */
.page-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin: 4rem 0 2rem;
  border-top: 1px solid var(--surface-border);
  padding-top: 2rem;
}

.page-nav-prev, .page-nav-next {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: 1rem 1.25rem;
  border: 1px solid var(--surface-border);
  border-radius: 10px;
  text-decoration: none;
  color: inherit;
  flex: 1;
  transition: border-color 0.15s, background 0.15s;
}

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

.page-nav-prev:hover, .page-nav-next:hover {
  border-color: var(--nvidia-green);
  background: var(--callout-bg);
  text-decoration: none;
}

.page-nav-label {
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.page-nav-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
}

/* ===== Hero (index.html) ===== */
.hero {
  padding: 5rem 0 2.5rem;
  border-bottom: 1px solid var(--surface-border);
  margin-bottom: 2.5rem;
}

.hero-label {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--nvidia-green);
  margin-bottom: 1rem;
}

.hero h1 { margin-bottom: 1.25rem; }

.hero-lead {
  font-size: clamp(1.05rem, 2vw, 1.2rem);
  color: var(--text-secondary);
  max-width: 62ch;
  margin-bottom: 0;
}

/* Path picker */
.path-picker {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  margin-bottom: 0;
}

.path-btn {
  padding: 0.6rem 1.25rem;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  border: 1.5px solid var(--surface-border);
  background: var(--surface);
  color: var(--text-secondary);
  cursor: pointer;
  text-decoration: none;
  transition: border-color 0.15s, color 0.15s, background 0.15s;
  display: inline-block;
}

.path-btn:hover {
  border-color: var(--nvidia-green);
  color: var(--nvidia-green);
  text-decoration: none;
}

.path-btn.primary {
  background: var(--nvidia-green);
  border-color: var(--nvidia-green);
  color: #fff;
}

.path-btn.primary:hover {
  background: var(--nvidia-green-dark);
  border-color: var(--nvidia-green-dark);
  color: #fff;
}

/* ===== Table ===== */
.styled-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
  margin: 1.5rem 0;
}

.styled-table th {
  text-align: left;
  padding: 0.6rem 0.85rem;
  background: var(--bg-secondary);
  color: var(--text-secondary);
  font-weight: 600;
  font-size: 0.75rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  border-bottom: 2px solid var(--surface-border);
}

.styled-table td {
  padding: 0.65rem 0.85rem;
  border-bottom: 1px solid var(--surface-border);
  color: var(--text-secondary);
  vertical-align: top;
}

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

.styled-table tr:hover td { background: var(--bg-secondary); }

/* ===== Badge / Pill ===== */
.badge {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  padding: 0.2em 0.6em;
  border-radius: 20px;
  text-transform: uppercase;
}

.badge-green  { background: #d1f5a0; color: #2d5a00; }
.badge-yellow { background: #fef3c7; color: #92400e; }
.badge-red    { background: #fee2e2; color: #991b1b; }
.badge-spark  { background: #e0e7ff; color: #3730a3; }

[data-theme="dark"] .badge-green  { background: #1a3200; color: #76B900; }
[data-theme="dark"] .badge-yellow { background: #3d2a00; color: #fbbf24; }
[data-theme="dark"] .badge-red    { background: #3d0000; color: #f87171; }
[data-theme="dark"] .badge-spark  { background: #1e1b4b; color: #818cf8; }

/* ===== Tool tag pill ===== */
.tool-tag {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 500;
  padding: 0.25em 0.65em;
  border: 1px solid var(--surface-border);
  border-radius: 6px;
  color: var(--text-secondary);
  margin: 0.2rem 0.2rem 0.2rem 0;
}

/* ===== Info box ===== */
.info-box {
  background: var(--bg-secondary);
  border: 1px solid var(--surface-border);
  border-radius: 10px;
  padding: 1.25rem 1.5rem;
  margin: 1.5rem 0;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .nav-links, .nav-direct-links { display: none; }
  .nav-hamburger { display: flex; }

  .hero { padding: 3.5rem 0 2.5rem; }

  .page-nav { flex-direction: column; }
  .page-nav-next { text-align: left; }

  .card-grid { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
  .page-wrapper { padding: 0 1rem; }
  .diagram-wrap { padding: 1rem; }
}