/* ═══════════════════════════════════════════════════════════════════
   ITK — Injection Toolkit Design System
   Modern dark tech (Vercel/Linear-inspired)
   ═══════════════════════════════════════════════════════════════════ */

/* ── Fonts ────────────────────────────────────────────────────────── */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500&display=swap');

/* ── Custom Properties ────────────────────────────────────────────── */
:root {
  --bg:           #0a0a0b;
  --bg-raised:    #111113;
  --bg-card:      #16161a;
  --bg-code:      #1a1a20;
  --border:       #27272a;
  --border-light: #3f3f46;
  --text:         #e4e4e7;
  --text-muted:   #a1a1aa;
  --text-dim:     #71717a;
  --accent:       #7c5bf0;
  --accent-end:   #5b8cf0;
  --gradient:     linear-gradient(135deg, var(--accent), var(--accent-end));
  --font-body:    'Inter', system-ui, -apple-system, sans-serif;
  --font-mono:    'JetBrains Mono', ui-monospace, 'Cascadia Code', monospace;
  --radius:       8px;
  --radius-lg:    12px;
  --transition:   0.25s cubic-bezier(0.4, 0, 0.2, 1);
  --nav-height:   64px;
  --max-width:    1200px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-height) + 24px);
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-body);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  font-size: clamp(0.938rem, 0.9rem + 0.2vw, 1rem);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

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

img, svg { max-width: 100%; height: auto; display: block; }
ul, ol { list-style: none; }
h1, h2, h3, h4 { line-height: 1.3; font-weight: 600; color: #fff; }

h1 { font-size: clamp(2rem, 1.5rem + 2.5vw, 3.25rem); }
h2 { font-size: clamp(1.5rem, 1.2rem + 1.5vw, 2.25rem); }
h3 { font-size: clamp(1.15rem, 1rem + 0.5vw, 1.5rem); }

/* ── Layout Helpers ───────────────────────────────────────────────── */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

section {
  padding: 80px 0;
}

.section-label {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  background: var(--gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 12px;
}

.section-title {
  margin-bottom: 16px;
}

.section-desc {
  color: var(--text-muted);
  max-width: 640px;
  margin-bottom: 48px;
}

/* ── Navigation ───────────────────────────────────────────────────── */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-height);
  background: rgba(10, 10, 11, 0.8);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
}

.navbar .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-weight: 700;
  font-size: 1.15rem;
  color: #fff;
  display: flex;
  align-items: center;
  gap: 8px;
}

.nav-logo span {
  background: var(--gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
}

.nav-links a {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-muted);
  position: relative;
  padding: 4px 0;
  transition: color var(--transition);
}

.nav-links a:hover,
.nav-links a.active {
  color: #fff;
}

.nav-links a.active::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--gradient);
  border-radius: 1px;
}

.nav-links .github-link {
  display: flex;
  align-items: center;
}

.nav-links .github-link svg {
  width: 20px;
  height: 20px;
  fill: var(--text-muted);
  transition: fill var(--transition);
}

.nav-links .github-link:hover svg {
  fill: #fff;
}

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text);
  border-radius: 1px;
  transition: var(--transition);
}

.hamburger.active span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.hamburger.active span:nth-child(2) { opacity: 0; }
.hamburger.active span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

/* Mobile overlay */
.nav-overlay {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 999;
  background: rgba(10, 10, 11, 0.95);
  backdrop-filter: blur(16px);
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 32px;
}

.nav-overlay.active { display: flex; }

.nav-overlay a {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text);
}

.nav-overlay a:hover { color: var(--accent); }

@media (max-width: 768px) {
  .nav-links { display: none; }
  .hamburger { display: flex; }
}

/* ── Breadcrumbs ──────────────────────────────────────────────────── */
.breadcrumbs {
  padding-top: calc(var(--nav-height) + 24px);
  padding-bottom: 0;
  font-size: 0.85rem;
  color: var(--text-dim);
}

.breadcrumbs a { color: var(--text-muted); }
.breadcrumbs a:hover { color: var(--accent-end); }
.breadcrumbs span { margin: 0 8px; color: var(--border-light); }

/* ── Hero ─────────────────────────────────────────────────────────── */
.hero {
  position: relative;
  min-height: 90vh;
  display: flex;
  align-items: center;
  text-align: center;
  padding-top: var(--nav-height);
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  left: 50%;
  width: 800px;
  height: 800px;
  transform: translateX(-50%);
  background: radial-gradient(circle, rgba(124, 91, 240, 0.12) 0%, transparent 70%);
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
  width: 100%;
}

.hero h1 {
  margin-bottom: 20px;
}

.hero h1 .gradient {
  background: var(--gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-tagline {
  font-size: clamp(1.1rem, 0.9rem + 1vw, 1.4rem);
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto 40px;
}

.hero-ctas {
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}

/* ── Buttons ──────────────────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: var(--radius);
  font-size: 0.938rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: var(--transition);
}

.btn-primary {
  background: var(--gradient);
  color: #fff;
}

.btn-primary:hover {
  opacity: 0.9;
  transform: translateY(-1px);
  color: #fff;
}

.btn-secondary {
  background: var(--bg-card);
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  border-color: var(--border-light);
  color: #fff;
  transform: translateY(-1px);
}

/* ── Cards ────────────────────────────────────────────────────────── */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: var(--transition);
}

.card:hover {
  border-color: var(--border-light);
  transform: translateY(-2px);
}

.card-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius);
  background: var(--gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
  font-size: 1.1rem;
  color: #fff;
}

.card h3 {
  font-size: 1.1rem;
  margin-bottom: 8px;
}

.card p {
  color: var(--text-muted);
  font-size: 0.875rem;
}

.card .mono {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent-end);
}

/* ── Stats Strip ──────────────────────────────────────────────────── */
.stats-strip {
  padding: 48px 0;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  background: var(--bg-raised);
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  text-align: center;
}

.stat-card {
  padding: 24px 16px;
}

.stat-value {
  font-size: clamp(1.75rem, 1.5rem + 1.5vw, 2.5rem);
  font-weight: 700;
  background: var(--gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1.2;
}

.stat-label {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-top: 4px;
}

@media (max-width: 768px) {
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 480px) {
  .stats-grid { grid-template-columns: 1fr; }
}

/* ── Featured Project Card ────────────────────────────────────────── */
.featured-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 40px;
  display: flex;
  gap: 40px;
  align-items: center;
}

.featured-card .featured-info { flex: 1; }
.featured-card .featured-info h3 { font-size: 1.5rem; margin-bottom: 12px; }
.featured-card .featured-info p { color: var(--text-muted); margin-bottom: 24px; }

.featured-card .feature-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 24px;
}

@media (max-width: 768px) {
  .featured-card { flex-direction: column; padding: 28px; }
}

/* ── Pill Badges ──────────────────────────────────────────────────── */
.pill {
  display: inline-block;
  padding: 6px 14px;
  border-radius: 9999px;
  font-size: 0.8rem;
  font-weight: 500;
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-muted);
}

.pill-accent {
  border-color: rgba(124, 91, 240, 0.3);
  color: var(--accent);
}

.pills-wrap {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
}

/* ── Tables ───────────────────────────────────────────────────────── */
.table-wrap {
  overflow-x: auto;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
}

th, td {
  padding: 12px 16px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

th {
  background: var(--bg-raised);
  font-weight: 600;
  color: #fff;
  white-space: nowrap;
}

td { color: var(--text-muted); }

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

tr:hover td { background: rgba(255, 255, 255, 0.02); }

td code {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  background: var(--bg-code);
  padding: 2px 6px;
  border-radius: 4px;
  color: var(--accent-end);
}

/* ── Code Blocks ──────────────────────────────────────────────────── */
pre {
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.6;
  color: var(--text-muted);
  margin: 16px 0;
}

code {
  font-family: var(--font-mono);
  font-size: 0.85em;
}

p code, li code {
  background: var(--bg-code);
  padding: 2px 6px;
  border-radius: 4px;
  color: var(--accent-end);
  font-size: 0.85em;
}

.copy-btn {
  position: absolute;
  top: 8px;
  right: 8px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-muted);
  padding: 4px 10px;
  font-size: 0.75rem;
  border-radius: 4px;
  cursor: pointer;
  font-family: var(--font-body);
  transition: var(--transition);
}

.copy-btn:hover {
  border-color: var(--border-light);
  color: #fff;
}

/* ── Tabs ─────────────────────────────────────────────────────────── */
.tabs {
  display: flex;
  gap: 0;
  border-bottom: 1px solid var(--border);
  margin-bottom: 24px;
}

.tab-btn {
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  padding: 10px 20px;
  color: var(--text-muted);
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  font-family: var(--font-body);
  transition: var(--transition);
}

.tab-btn:hover { color: var(--text); }

.tab-btn.active {
  color: #fff;
  border-bottom-color: var(--accent);
}

.tab-panel { display: none; }
.tab-panel.active { display: block; }

/* ── Accordion ────────────────────────────────────────────────────── */
.accordion-item {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 8px;
  overflow: hidden;
}

.accordion-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  background: var(--bg-card);
  cursor: pointer;
  font-weight: 600;
  color: #fff;
  transition: var(--transition);
  user-select: none;
}

.accordion-header:hover { background: var(--bg-raised); }

.accordion-header::after {
  content: '+';
  font-size: 1.25rem;
  color: var(--text-dim);
  transition: transform var(--transition);
}

.accordion-item.open .accordion-header::after {
  content: '\2212';
}

.accordion-body {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s ease;
}

.accordion-body-inner {
  padding: 20px;
  color: var(--text-muted);
  font-size: 0.9rem;
  line-height: 1.8;
}

/* ── Docs Sidebar TOC ─────────────────────────────────────────────── */
.docs-layout {
  display: flex;
  gap: 48px;
  padding-top: calc(var(--nav-height) + 24px);
}

.toc {
  position: sticky;
  top: calc(var(--nav-height) + 24px);
  width: 240px;
  flex-shrink: 0;
  max-height: calc(100vh - var(--nav-height) - 48px);
  overflow-y: auto;
  padding-right: 16px;
  border-right: 1px solid var(--border);
}

.toc h4 {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-dim);
  margin-bottom: 12px;
  margin-top: 20px;
}

.toc h4:first-child { margin-top: 0; }

.toc a {
  display: block;
  padding: 4px 12px;
  font-size: 0.825rem;
  color: var(--text-muted);
  border-left: 2px solid transparent;
  margin-bottom: 2px;
  transition: var(--transition);
}

.toc a:hover {
  color: #fff;
  border-left-color: var(--border-light);
}

.toc a.active {
  color: var(--accent);
  border-left-color: var(--accent);
}

.docs-content {
  flex: 1;
  min-width: 0;
}

@media (max-width: 1023px) {
  .docs-layout { flex-direction: column; gap: 24px; }
  .toc {
    position: static;
    width: 100%;
    max-height: none;
    border-right: none;
    border-bottom: 1px solid var(--border);
    padding-right: 0;
    padding-bottom: 16px;
    display: flex;
    flex-wrap: wrap;
    gap: 4px 16px;
  }
  .toc h4 { width: 100%; margin-top: 12px; }
  .toc a { border-left: none; padding: 4px 8px; }
}

/* ── SVG Diagrams ─────────────────────────────────────────────────── */
.diagram-wrap {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 32px;
  margin: 24px 0;
  overflow-x: auto;
}

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

/* ── Protocol Header Visual ───────────────────────────────────────── */
.header-visual {
  display: flex;
  gap: 0;
  margin: 24px 0;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
}

.header-field {
  flex: 1;
  text-align: center;
  padding: 16px 12px;
  background: var(--bg-card);
  border-right: 1px solid var(--border);
}

.header-field:last-child { border-right: none; }

.header-field .field-name {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--accent-end);
  font-weight: 500;
}

.header-field .field-size {
  font-size: 0.7rem;
  color: var(--text-dim);
  margin-top: 4px;
}

@media (max-width: 600px) {
  .header-visual { flex-direction: column; }
  .header-field { border-right: none; border-bottom: 1px solid var(--border); }
  .header-field:last-child { border-bottom: none; }
}

/* ── Three-Column Layout ──────────────────────────────────────────── */
.three-col {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

@media (max-width: 768px) {
  .three-col { grid-template-columns: 1fr; }
}

/* ── Does / Doesn't Lists ─────────────────────────────────────────── */
.does-list li, .doesnt-list li {
  padding: 4px 0 4px 24px;
  position: relative;
  font-size: 0.875rem;
  color: var(--text-muted);
}

.does-list li::before {
  content: '\2713';
  position: absolute;
  left: 0;
  color: #4ade80;
  font-weight: 700;
}

.doesnt-list li::before {
  content: '\2717';
  position: absolute;
  left: 0;
  color: #f87171;
  font-weight: 700;
}

/* ── Seqlock Timeline ─────────────────────────────────────────────── */
.timeline-row {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 8px 0;
}

.timeline-label {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  width: 64px;
  text-align: right;
  color: var(--text-muted);
  flex-shrink: 0;
}

.timeline-bar {
  flex: 1;
  height: 36px;
  background: var(--bg-code);
  border-radius: 4px;
  position: relative;
  overflow: hidden;
}

.timeline-segment {
  position: absolute;
  top: 4px;
  bottom: 4px;
  border-radius: 3px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  font-family: var(--font-mono);
  color: #fff;
}

.seg-write { background: var(--accent); }
.seg-read { background: var(--accent-end); }
.seg-retry { background: #f87171; opacity: 0.7; }

/* ── Fade-in Animations ───────────────────────────────────────────── */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

.fade-in:nth-child(2) { transition-delay: 0.1s; }
.fade-in:nth-child(3) { transition-delay: 0.2s; }
.fade-in:nth-child(4) { transition-delay: 0.15s; }
.fade-in:nth-child(5) { transition-delay: 0.2s; }
.fade-in:nth-child(6) { transition-delay: 0.25s; }

/* ── Footer ───────────────────────────────────────────────────────── */
.footer {
  border-top: 1px solid var(--border);
  padding: 40px 0;
  text-align: center;
  color: var(--text-dim);
  font-size: 0.825rem;
}

.footer p { margin-bottom: 8px; }
.footer a { color: var(--text-muted); }
.footer a:hover { color: var(--accent-end); }

.footer-ai {
  font-style: italic;
  color: var(--text-dim);
  opacity: 0.7;
}

/* ── Page header (inner pages) ────────────────────────────────────── */
.page-header {
  padding-top: calc(var(--nav-height) + 48px);
  padding-bottom: 48px;
  text-align: center;
  position: relative;
}

.page-header::before {
  content: '';
  position: absolute;
  top: 0;
  left: 50%;
  width: 600px;
  height: 400px;
  transform: translateX(-50%);
  background: radial-gradient(circle, rgba(124, 91, 240, 0.08) 0%, transparent 70%);
  pointer-events: none;
}

.page-header p {
  color: var(--text-muted);
  max-width: 600px;
  margin: 16px auto 0;
}

/* ── Principle Cards ──────────────────────────────────────────────── */
.principle-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 20px;
}

.principle-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  border-top: 3px solid transparent;
  border-image: var(--gradient) 1;
  border-image-slice: 1 0 0 0;
}

.principle-card h3 {
  font-size: 1rem;
  margin-bottom: 8px;
}

.principle-card p {
  color: var(--text-muted);
  font-size: 0.875rem;
}

/* ── Docs sections ────────────────────────────────────────────────── */
.docs-section {
  padding-bottom: 48px;
  margin-bottom: 48px;
  border-bottom: 1px solid var(--border);
}

.docs-section:last-child {
  border-bottom: none;
}

.docs-section h2 {
  margin-bottom: 16px;
}

.docs-section h3 {
  margin-top: 32px;
  margin-bottom: 12px;
}

.docs-section p,
.docs-section ul {
  margin-bottom: 16px;
  color: var(--text-muted);
}

.docs-section ul {
  padding-left: 20px;
}

.docs-section ul li {
  list-style: disc;
  margin-bottom: 6px;
  font-size: 0.9rem;
}

/* ── Utility ──────────────────────────────────────────────────────── */
.text-center { text-align: center; }
.mt-2 { margin-top: 16px; }
.mt-4 { margin-top: 32px; }
.mb-2 { margin-bottom: 16px; }
.mb-4 { margin-bottom: 32px; }
.text-muted { color: var(--text-muted); }
.text-dim { color: var(--text-dim); }
.mono { font-family: var(--font-mono); }

/* ── Responsive card grid tweaks ──────────────────────────────────── */
@media (max-width: 768px) {
  section { padding: 48px 0; }
  .card-grid { grid-template-columns: 1fr; }
  .container { padding: 0 16px; }
}

@media (min-width: 769px) and (max-width: 1023px) {
  .card-grid { grid-template-columns: repeat(2, 1fr); }
}

/* ── Animated gradient keyframes (hero bg) ────────────────────────── */
@keyframes gradient-shift {
  0%   { background-position: 0% 50%; }
  50%  { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

.animated-gradient {
  background: linear-gradient(135deg, rgba(124,91,240,0.1), rgba(91,140,240,0.1), rgba(124,91,240,0.05));
  background-size: 400% 400%;
  animation: gradient-shift 8s ease infinite;
}

/* ── SVG animation helpers ────────────────────────────────────────── */
@keyframes dash-flow {
  to { stroke-dashoffset: -20; }
}

.flow-line {
  stroke-dasharray: 8 4;
  animation: dash-flow 1.5s linear infinite;
}

/* ── Comparison table special styles ──────────────────────────────── */
.comparison-table th:first-child,
.comparison-table td:first-child {
  font-weight: 600;
  color: #fff;
}