/* ==========================================================================
   MITCEVPN - QUANTUM GRID NETWORK DESIGN SYSTEM
   Dark Technology | Network Infrastructure | Precision Grid | System Layers
   ========================================================================== */

:root {
  --bg-main: #050914;
  --bg-second: #0B1220;
  --bg-surface: #101B30;
  --bg-surface-light: #13213A;
  --text-primary: #FFFFFF;
  --text-body: #C1CCDA;
  --text-secondary: #91A4BF;
  --electric-blue: #3B82F6;
  --cyan: #22D3EE;
  --signal-green: #38F2B2;
  --border: rgba(145, 164, 191, 0.18);
  --border-bright: rgba(34, 211, 238, 0.4);
  --border-glow: rgba(59, 130, 246, 0.35);
  --font-mono: "SF Mono", "JetBrains Mono", Consolas, "Liberation Mono", Menlo, Courier, monospace;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif;
  --header-height: 68px;
  --container-max: 1200px;
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --transition: 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 24px);
  background-color: var(--bg-main);
  color: var(--text-body);
  font-family: var(--font-sans);
  line-height: 1.65;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background-color: var(--bg-main);
  background-image: 
    linear-gradient(to right, rgba(145, 164, 191, 0.04) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(145, 164, 191, 0.04) 1px, transparent 1px);
  background-size: 32px 32px;
  color: var(--text-body);
  position: relative;
  overflow-x: hidden;
}

/* Background Quantum Mesh Ambient */
body::before {
  content: "";
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 100vw;
  max-width: 1440px;
  height: 780px;
  background: radial-gradient(circle at 50% 180px, rgba(59, 130, 246, 0.12) 0%, rgba(34, 211, 238, 0.04) 40%, transparent 70%);
  pointer-events: none;
  z-index: 0;
}

/* Container */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
  position: relative;
  z-index: 1;
}

/* Typography Utilities */
h1, h2, h3, h4, h5, h6 {
  color: var(--text-primary);
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: -0.02em;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color var(--transition), border-color var(--transition);
}

p {
  margin-bottom: 1.25rem;
}

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

/* Monospace & System Tags */
.sys-tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--cyan);
  background: rgba(34, 211, 238, 0.08);
  border: 1px solid rgba(34, 211, 238, 0.25);
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  white-space: nowrap;
}

.sys-tag.subtle {
  color: var(--text-secondary);
  background: rgba(145, 164, 191, 0.08);
  border-color: var(--border);
}

.sys-tag.green {
  color: var(--signal-green);
  background: rgba(56, 242, 178, 0.08);
  border-color: rgba(56, 242, 178, 0.25);
}

.sys-id {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--cyan);
  letter-spacing: 0.06em;
}

/* Buttons & Commercial CTA */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-size: 0.95rem;
  font-weight: 600;
  padding: 10px 22px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition);
  text-decoration: none;
  line-height: 1.4;
  border: 1px solid transparent;
}

.btn-primary {
  background: var(--electric-blue);
  color: #FFFFFF;
  box-shadow: 0 0 20px rgba(59, 130, 246, 0.35);
}

.btn-primary:hover {
  background: #2563EB;
  box-shadow: 0 0 28px rgba(59, 130, 246, 0.55);
  transform: translateY(-1px);
}

.btn-secondary {
  background: var(--bg-surface);
  color: var(--text-primary);
  border-color: var(--border);
}

.btn-secondary:hover {
  background: var(--bg-surface-light);
  border-color: var(--cyan);
  color: #FFFFFF;
}

.btn-cyan {
  background: transparent;
  color: var(--cyan);
  border-color: rgba(34, 211, 238, 0.4);
}

.btn-cyan:hover {
  background: rgba(34, 211, 238, 0.12);
  border-color: var(--cyan);
  box-shadow: 0 0 16px rgba(34, 211, 238, 0.25);
}

.btn-link {
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 0;
  border-bottom: 1px dashed transparent;
}

.btn-link:hover {
  color: #FFFFFF;
  border-bottom-color: var(--cyan);
}

/* ==========================================================================
   HEADER: SYSTEM HEADER
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: rgba(5, 9, 20, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  z-index: 100;
  display: flex;
  align-items: center;
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

.brand-wrapper {
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.brand-logo {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 8px;
}

.brand-logo .dot {
  width: 7px;
  height: 7px;
  background-color: var(--cyan);
  border-radius: 50%;
  box-shadow: 0 0 8px var(--cyan);
}

.brand-sub {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.14em;
  color: var(--text-secondary);
  text-transform: uppercase;
}

/* Navigation Links */
.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
  list-style: none;
}

.nav-links a {
  font-size: 0.85rem;
  font-weight: 600;
  font-family: var(--font-mono);
  letter-spacing: 0.06em;
  color: var(--text-secondary);
  transition: color var(--transition);
  position: relative;
  padding: 6px 0;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--text-primary);
}

.nav-links a::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0%;
  height: 2px;
  background: var(--cyan);
  transition: width var(--transition);
}

.nav-links a:hover::after,
.nav-links a.active::after {
  width: 100%;
}

/* Header Right / Status Indicator */
.header-actions {
  display: flex;
  align-items: center;
  gap: 20px;
}

.system-status {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--text-secondary);
  letter-spacing: 0.08em;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  background: rgba(11, 18, 32, 0.8);
  border: 1px solid var(--border);
}

.status-dot {
  width: 6px;
  height: 6px;
  background-color: var(--signal-green);
  border-radius: 50%;
  box-shadow: 0 0 8px var(--signal-green);
}

/* Mobile Toggle */
.mobile-menu-btn {
  display: none;
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
}

/* Mobile Drawer */
.mobile-nav {
  display: none;
  position: fixed;
  top: var(--header-height);
  left: 0;
  right: 0;
  background: rgba(5, 9, 20, 0.98);
  border-bottom: 1px solid var(--border);
  padding: 24px;
  flex-direction: column;
  gap: 16px;
  z-index: 99;
}

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

.mobile-nav a {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-body);
  padding: 10px 0;
  border-bottom: 1px solid rgba(145, 164, 191, 0.1);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.mobile-nav a:hover {
  color: var(--cyan);
}

/* ==========================================================================
   HERO: CENTERED QUANTUM HERO
   ========================================================================== */
.hero-section {
  padding: 64px 0 54px;
  position: relative;
  text-align: center;
  border-bottom: 1px solid var(--border);
}

.hero-tags-row {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 28px;
}

.hero-brand-name {
  font-size: clamp(3.2rem, 5.5vw, 4.25rem);
  font-weight: 800;
  letter-spacing: 0.04em;
  color: var(--text-primary);
  line-height: 1.1;
  margin-bottom: 12px;
  text-shadow: 0 0 40px rgba(59, 130, 246, 0.2);
}

.hero-slogan {
  font-size: clamp(2rem, 3.8vw, 3rem);
  font-weight: 700;
  line-height: 1.25;
  color: var(--text-primary);
  margin-bottom: 18px;
}

.hero-slogan .gradient-text {
  background: linear-gradient(135deg, #FFFFFF 30%, var(--cyan) 90%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-h1-sub {
  font-size: clamp(1.2rem, 2vw, 1.45rem);
  font-weight: 500;
  color: var(--cyan);
  margin-bottom: 22px;
  letter-spacing: -0.01em;
}

.hero-desc {
  max-width: 760px;
  margin: 0 auto 36px;
  font-size: 1.05rem;
  line-height: 1.75;
  color: var(--text-body);
}

.hero-cta-group {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 16px;
  margin-bottom: 54px;
}

/* Hero Bottom: SYSTEM SUMMARY (NOT cards, 4 horizontal fields with thin dividers) */
.system-summary-strip {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  max-width: 960px;
  margin: 0 auto;
  padding: 18px 24px;
  background: rgba(11, 18, 32, 0.65);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  backdrop-filter: blur(8px);
}

.summary-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  position: relative;
  padding: 4px 16px;
}

.summary-item:not(:last-child)::after {
  content: "";
  position: absolute;
  right: 0;
  top: 15%;
  height: 70%;
  width: 1px;
  background: var(--border);
}

.summary-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  color: var(--text-secondary);
  text-transform: uppercase;
  margin-bottom: 4px;
}

.summary-value {
  font-family: var(--font-mono);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: 0.05em;
}

.summary-value span {
  color: var(--cyan);
  margin-right: 4px;
}

/* ==========================================================================
   COMMON SECTION STYLES
   ========================================================================== */
.section {
  padding: 80px 0;
  position: relative;
  border-bottom: 1px solid var(--border);
}

.section-header {
  margin-bottom: 48px;
}

.section-header.center {
  text-align: center;
}

.section-id {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  color: var(--cyan);
  text-transform: uppercase;
  margin-bottom: 8px;
  display: block;
}

.section-title {
  font-size: clamp(1.8rem, 3vw, 2.4rem);
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 12px;
}

.section-desc {
  max-width: 680px;
  font-size: 1rem;
  color: var(--text-secondary);
}

.section-header.center .section-desc {
  margin: 0 auto;
}

/* ==========================================================================
   01 / NETWORK MATRIX
   ========================================================================== */
.network-matrix {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.matrix-quadrant {
  background: var(--bg-second);
  padding: 36px 40px;
  position: relative;
  transition: background var(--transition);
}

.matrix-quadrant:hover {
  background: #0E172A;
}

.matrix-region-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 24px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--border);
}

.matrix-region-title {
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--text-primary);
  text-transform: uppercase;
  font-family: var(--font-mono);
}

.matrix-node-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.matrix-node-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.95rem;
  color: var(--text-body);
}

.node-name-wrap {
  display: flex;
  align-items: center;
  gap: 12px;
}

.node-dot {
  width: 6px;
  height: 6px;
  background-color: var(--cyan);
  border-radius: 50%;
  box-shadow: 0 0 6px var(--cyan);
}

.node-code {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-secondary);
  background: rgba(145, 164, 191, 0.08);
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  border: 1px solid rgba(145, 164, 191, 0.14);
}

/* ==========================================================================
   02 / SYSTEM LAYERS
   ========================================================================== */
.system-layers-stack {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.layer-bar {
  background: var(--bg-second);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 24px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: all var(--transition);
  position: relative;
}

/* Progressive Indent (Desktop) */
.layer-bar:nth-child(1) { margin-left: 0; }
.layer-bar:nth-child(2) { margin-left: 24px; }
.layer-bar:nth-child(3) { margin-left: 48px; }
.layer-bar:nth-child(4) { margin-left: 72px; }

.layer-bar:hover {
  border-color: var(--cyan);
  box-shadow: 0 0 24px rgba(34, 211, 238, 0.12);
  transform: translateX(4px);
  background: #0E172A;
}

.layer-left {
  display: flex;
  align-items: center;
  gap: 28px;
}

.layer-badge {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--cyan);
  letter-spacing: 0.08em;
  background: rgba(34, 211, 238, 0.08);
  border: 1px solid rgba(34, 211, 238, 0.2);
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  white-space: nowrap;
}

.layer-heading {
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--text-primary);
  font-family: var(--font-mono);
}

.layer-desc {
  font-size: 0.95rem;
  color: var(--text-secondary);
  margin-bottom: 0;
}

.layer-indicator {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--signal-green);
  display: flex;
  align-items: center;
  gap: 6px;
  white-space: nowrap;
}

.layer-indicator::before {
  content: "";
  width: 6px;
  height: 6px;
  background: var(--signal-green);
  border-radius: 50%;
  box-shadow: 0 0 6px var(--signal-green);
}

/* ==========================================================================
   03 / DEVICE ACCESS
   ========================================================================== */
.device-access-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.device-row {
  background: var(--bg-second);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 20px 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: all var(--transition);
}

.device-row:hover {
  background: #0E172A;
  border-color: var(--cyan);
  transform: translateX(4px);
}

.device-left {
  display: flex;
  align-items: center;
  gap: 24px;
}

.device-id {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--text-secondary);
  font-weight: 600;
}

.device-os-wrap {
  display: flex;
  align-items: center;
  gap: 14px;
}

.device-icon {
  width: 20px;
  height: 20px;
  color: var(--cyan);
  display: flex;
  align-items: center;
  justify-content: center;
}

.device-os {
  font-family: var(--font-mono);
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: 0.04em;
}

.device-type {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  color: var(--text-secondary);
  text-transform: uppercase;
}

/* ==========================================================================
   04 / AI NETWORK
   ========================================================================== */
.ai-network-pipeline {
  background: var(--bg-second);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 36px;
  margin-bottom: 28px;
  position: relative;
  overflow: hidden;
}

.ai-pipeline-wire {
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: relative;
  padding: 20px 0;
  margin-bottom: 36px;
  border-bottom: 1px dashed var(--border);
}

.wire-step {
  display: flex;
  flex-direction: column;
  gap: 4px;
  position: relative;
  z-index: 2;
}

.wire-step-tag {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--cyan);
  letter-spacing: 0.08em;
}

.wire-step-name {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-primary);
}

/* Moving Light Dot across AI Line */
.wire-track {
  position: absolute;
  top: 50%;
  left: 180px;
  right: 180px;
  height: 2px;
  background: rgba(145, 164, 191, 0.15);
  transform: translateY(-50%);
  overflow: hidden;
}

.wire-pulse {
  position: absolute;
  top: 0;
  left: 0;
  width: 40px;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--cyan), transparent);
  box-shadow: 0 0 10px var(--cyan);
  animation: movePulse 8s linear infinite;
}

@keyframes movePulse {
  0% { transform: translateX(-100%); }
  100% { transform: translateX(800%); }
}

.ai-tools-grid {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 12px;
}

.ai-tool-item {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 16px 12px;
  text-align: center;
  transition: all var(--transition);
}

.ai-tool-item:hover {
  border-color: var(--cyan);
  transform: translateY(-2px);
  background: var(--bg-surface-light);
}

.ai-tool-num {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--cyan);
  margin-bottom: 6px;
}

.ai-tool-name {
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.ai-tool-proto {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--text-secondary);
}

.ai-link-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
  padding: 16px 24px;
  background: rgba(11, 18, 32, 0.7);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}

/* ==========================================================================
   05 / SIGNAL CHANNELS (STREAMING)
   ========================================================================== */
.signal-channels-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 28px;
}

.channel-row {
  position: relative;
  background: var(--bg-second);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 22px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  overflow: hidden;
  transition: border-color var(--transition);
}

/* Cyan Sweep Line on Hover */
.channel-row::before {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--cyan), var(--electric-blue));
  transition: width 0.4s ease;
}

.channel-row:hover::before {
  width: 100%;
}

.channel-row:hover {
  border-color: rgba(34, 211, 238, 0.4);
}

.channel-left {
  display: flex;
  align-items: center;
  gap: 28px;
}

.channel-num {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--cyan);
  letter-spacing: 0.08em;
}

.channel-name {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
}

.channel-meta {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-secondary);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

/* ==========================================================================
   06 / NETWORK TIERS (PRICING)
   ========================================================================== */
.network-tier-stack {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.tier-strip {
  background: var(--bg-second);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 26px 36px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: relative;
  transition: all var(--transition);
}

.tier-strip:hover {
  border-color: rgba(59, 130, 246, 0.5);
  box-shadow: 0 0 24px rgba(59, 130, 246, 0.12);
  transform: translateX(4px);
}

/* Highlighted Tier: FOCUS */
.tier-strip.focus-tier {
  border-color: var(--cyan);
  background: #0D192E;
  box-shadow: 0 0 28px rgba(34, 211, 238, 0.15);
}

.tier-strip.focus-tier::after {
  content: "RECOMMENDED";
  position: absolute;
  top: -10px;
  right: 36px;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  color: #050914;
  background: var(--signal-green);
  padding: 2px 10px;
  border-radius: var(--radius-sm);
  box-shadow: 0 0 10px rgba(56, 242, 178, 0.4);
}

.tier-id-wrap {
  display: flex;
  align-items: center;
  gap: 20px;
  min-width: 180px;
}

.tier-code {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.tier-name {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  color: var(--text-primary);
  font-family: var(--font-mono);
}

.tier-bandwidth {
  display: flex;
  align-items: baseline;
  gap: 6px;
  min-width: 140px;
}

.tier-gb {
  font-family: var(--font-mono);
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--cyan);
}

.tier-data-label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-secondary);
}

.tier-features {
  display: flex;
  align-items: center;
  gap: 16px;
  font-size: 0.88rem;
  color: var(--text-body);
  flex-grow: 1;
  padding: 0 24px;
}

.tier-features span {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.tier-features span::before {
  content: "";
  width: 4px;
  height: 4px;
  background: var(--signal-green);
  border-radius: 50%;
}

.tier-price-cta {
  display: flex;
  align-items: center;
  gap: 24px;
  min-width: 220px;
  justify-content: flex-end;
}

.tier-price {
  font-family: var(--font-mono);
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-primary);
  white-space: nowrap;
}

.tier-period {
  font-size: 0.75rem;
  color: var(--text-secondary);
  font-weight: 400;
}

/* ==========================================================================
   07 / KNOWLEDGE NODES (BLOG SYSTEM)
   ========================================================================== */
.knowledge-nodes-mesh {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.knowledge-node-card {
  background: var(--bg-second);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: all var(--transition);
  position: relative;
}

.knowledge-node-card:hover {
  border-color: var(--cyan);
  box-shadow: 0 0 24px rgba(34, 211, 238, 0.12);
  transform: translateY(-2px);
}

.node-card-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
}

.node-meta-left {
  display: flex;
  align-items: center;
  gap: 12px;
}

.node-id-label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--cyan);
  letter-spacing: 0.08em;
}

.node-cat-badge {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  color: var(--text-secondary);
  background: rgba(145, 164, 191, 0.08);
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
}

.node-read-time {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-secondary);
}

.node-card-title {
  font-size: 1.15rem;
  font-weight: 700;
  line-height: 1.45;
  color: var(--text-primary);
  margin-bottom: 12px;
}

.node-card-title a:hover {
  color: var(--cyan);
}

.node-card-excerpt {
  font-size: 0.92rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 20px;
}

.node-card-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 14px;
  border-top: 1px solid rgba(145, 164, 191, 0.1);
}

/* ==========================================================================
   08 / FIELD SIGNALS (NOTES)
   ========================================================================== */
.field-signals-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.signal-note-item {
  background: var(--bg-second);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  position: relative;
  transition: all var(--transition);
}

.signal-note-item:hover {
  border-color: rgba(56, 242, 178, 0.4);
  background: #0E172A;
}

.signal-head {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 16px;
}

.signal-dot {
  width: 8px;
  height: 8px;
  background: var(--signal-green);
  border-radius: 50%;
  box-shadow: 0 0 8px var(--signal-green);
}

.signal-id {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--signal-green);
  letter-spacing: 0.08em;
}

.signal-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 10px;
}

.signal-text {
  font-size: 0.92rem;
  color: var(--text-body);
  line-height: 1.65;
  margin-bottom: 0;
}

/* ==========================================================================
   09 / SYSTEM QUERY (FAQ)
   ========================================================================== */
.faq-accordion-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
  max-width: 920px;
  margin: 0 auto;
}

.faq-item {
  background: var(--bg-second);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
  transition: border-color var(--transition);
}

.faq-item:hover {
  border-color: var(--cyan);
}

.faq-trigger {
  width: 100%;
  padding: 22px 28px;
  background: transparent;
  border: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  color: var(--text-primary);
  text-align: left;
  cursor: pointer;
  font-size: 1.05rem;
  font-weight: 600;
  font-family: var(--font-sans);
}

.faq-trigger-left {
  display: flex;
  align-items: center;
  gap: 18px;
}

.faq-query-num {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--cyan);
  letter-spacing: 0.08em;
  white-space: nowrap;
}

.faq-icon {
  font-family: var(--font-mono);
  font-size: 1.25rem;
  color: var(--text-secondary);
  transition: transform var(--transition);
  line-height: 1;
}

.faq-item.active .faq-icon {
  transform: rotate(45deg);
  color: var(--cyan);
}

.faq-body {
  display: none;
  padding: 0 28px 22px 64px;
  color: var(--text-body);
  font-size: 0.95rem;
  line-height: 1.7;
  border-top: 1px dashed rgba(145, 164, 191, 0.12);
}

.faq-item.active .faq-body {
  display: block;
  padding-top: 18px;
}

/* ==========================================================================
   FOOTER: COMPACT TECHNOLOGY FOOTER (~250-320px)
   ========================================================================== */
.site-footer {
  background: #03060E;
  border-top: 1px solid var(--border);
  padding: 48px 0 28px;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.footer-top-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr 1.5fr;
  gap: 32px;
  margin-bottom: 40px;
}

.footer-brand-col .brand-logo {
  margin-bottom: 12px;
}

.footer-brand-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 18px;
  max-width: 280px;
}

.footer-col-title {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.1em;
  color: var(--text-primary);
  text-transform: uppercase;
  margin-bottom: 16px;
}

.footer-nav-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-nav-list a {
  color: var(--text-secondary);
  transition: color var(--transition);
}

.footer-nav-list a:hover {
  color: var(--cyan);
}

.footer-bottom-strip {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 24px;
  border-top: 1px solid rgba(145, 164, 191, 0.1);
  font-family: var(--font-mono);
  font-size: 0.75rem;
}

.footer-links-inline {
  display: flex;
  align-items: center;
  gap: 18px;
}

/* External partner links section */
.footer-external-links {
  margin-top: 14px;
  padding-top: 14px;
  border-top: 1px dashed rgba(145, 164, 191, 0.1);
  font-size: 0.8rem;
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.footer-external-links span {
  font-family: var(--font-mono);
  color: var(--text-secondary);
}

.footer-external-links a {
  color: var(--text-secondary);
  border-bottom: 1px dotted rgba(145, 164, 191, 0.3);
}

.footer-external-links a:hover {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}

/* ==========================================================================
   SYSTEM READER: ARTICLE & CONTENT TEMPLATES
   ========================================================================== */
.breadcrumb-wrap {
  padding: 24px 0 0;
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-secondary);
}

.breadcrumb-wrap a {
  color: var(--text-secondary);
}

.breadcrumb-wrap a:hover {
  color: var(--cyan);
}

.breadcrumb-wrap .separator {
  color: var(--border);
}

.article-header {
  padding: 36px 0 40px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 40px;
}

.article-meta-tags {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 16px;
}

.article-h1 {
  font-size: clamp(2rem, 3.4vw, 2.75rem);
  font-weight: 800;
  line-height: 1.3;
  color: var(--text-primary);
  margin-bottom: 20px;
  letter-spacing: -0.02em;
}

.article-lead {
  font-size: 1.12rem;
  line-height: 1.75;
  color: var(--text-body);
  max-width: 820px;
  margin-bottom: 24px;
}

.article-author-strip {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 20px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-secondary);
  padding: 12px 18px;
  background: var(--bg-second);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  width: fit-content;
}

.article-author-strip span {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

/* GEO Quick Answer Box */
.quick-answer {
  background: rgba(34, 211, 238, 0.05);
  border: 1px solid rgba(34, 211, 238, 0.3);
  border-left: 4px solid var(--cyan);
  border-radius: var(--radius-sm);
  padding: 24px 28px;
  margin-bottom: 40px;
}

.quick-answer-tag {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--cyan);
  letter-spacing: 0.12em;
  display: block;
  margin-bottom: 8px;
}

.quick-answer h2 {
  font-size: 1.25rem;
  color: var(--text-primary);
  margin-bottom: 10px;
}

.quick-answer p {
  font-size: 1rem;
  line-height: 1.7;
  color: var(--text-body);
  margin-bottom: 0;
}

/* System Index (TOC) */
.system-toc {
  background: var(--bg-second);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 24px 30px;
  margin-bottom: 44px;
}

.toc-title {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.1em;
  color: var(--cyan);
  text-transform: uppercase;
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.toc-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.toc-item a {
  display: flex;
  align-items: baseline;
  gap: 12px;
  font-size: 0.92rem;
  color: var(--text-body);
}

.toc-item a:hover {
  color: var(--cyan);
}

.toc-num {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-secondary);
}

/* Article Content Layout */
.article-body {
  max-width: 820px;
  margin: 0 auto;
}

.article-content {
  font-size: 1.05rem;
  line-height: 1.8;
  color: var(--text-body);
}

.article-content h2 {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 48px 0 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
}

.article-content h3 {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 32px 0 12px;
}

.article-content ul,
.article-content ol {
  margin: 16px 0 24px 24px;
}

.article-content li {
  margin-bottom: 8px;
}

.article-content a {
  color: var(--cyan);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.article-content a:hover {
  color: #FFFFFF;
}

/* HTML Tables inside Articles */
.table-responsive {
  width: 100%;
  overflow-x: auto;
  margin: 28px 0;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}

.article-content table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.92rem;
  text-align: left;
  background: var(--bg-second);
}

.article-content th {
  background: var(--bg-surface);
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.05em;
  padding: 14px 18px;
  border-bottom: 1px solid var(--border);
}

.article-content td {
  padding: 14px 18px;
  border-bottom: 1px solid rgba(145, 164, 191, 0.1);
  color: var(--text-body);
}

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

.article-content tr:hover td {
  background: rgba(19, 33, 58, 0.5);
}

/* Callout Box inside Article */
.system-callout {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-left: 3px solid var(--electric-blue);
  border-radius: var(--radius-sm);
  padding: 20px 24px;
  margin: 28px 0;
}

.callout-title {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--electric-blue);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 8px;
}

/* Article CTA Box */
.article-cta-box {
  background: linear-gradient(135deg, var(--bg-surface) 0%, #0E1A33 100%);
  border: 1px solid var(--border-bright);
  border-radius: var(--radius-md);
  padding: 36px;
  margin: 48px 0;
  text-align: center;
  box-shadow: 0 0 30px rgba(34, 211, 238, 0.08);
}

.article-cta-box h3 {
  font-size: 1.4rem;
  color: var(--text-primary);
  margin-bottom: 10px;
}

.article-cta-box p {
  color: var(--text-body);
  max-width: 600px;
  margin: 0 auto 24px;
}

/* Related Articles Mesh */
.related-nodes-section {
  margin-top: 64px;
  padding-top: 40px;
  border-top: 1px solid var(--border);
}

/* Category Directory UI */
.category-directory {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-top: 36px;
}

.category-node-row {
  background: var(--bg-second);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 22px 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: all var(--transition);
}

.category-node-row:hover {
  border-color: var(--cyan);
  background: #0E172A;
  transform: translateX(4px);
}

.cat-node-left {
  display: flex;
  align-items: baseline;
  gap: 20px;
}

.cat-node-title {
  font-size: 1.08rem;
  font-weight: 700;
  color: var(--text-primary);
}

.cat-node-title:hover {
  color: var(--cyan);
}

/* Sitemap List Directory */
.sitemap-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 32px;
  margin-top: 40px;
}

.sitemap-group {
  background: var(--bg-second);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 28px;
}

.sitemap-group-title {
  font-size: 1.15rem;
  color: var(--text-primary);
  margin-bottom: 16px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border);
  font-family: var(--font-mono);
  display: flex;
  align-items: center;
  gap: 8px;
}

.sitemap-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.sitemap-list a {
  color: var(--text-body);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.sitemap-list a:hover {
  color: var(--cyan);
}

/* 404 Node Page */
.error-page-wrap {
  text-align: center;
  padding: 100px 0 120px;
}

.error-code {
  font-family: var(--font-mono);
  font-size: clamp(4rem, 10vw, 7rem);
  font-weight: 800;
  color: var(--cyan);
  letter-spacing: 0.08em;
  line-height: 1;
  margin-bottom: 12px;
  text-shadow: 0 0 30px rgba(34, 211, 238, 0.3);
}

.error-title {
  font-size: 1.8rem;
  color: var(--text-primary);
  margin-bottom: 16px;
}

.error-desc {
  max-width: 520px;
  margin: 0 auto 36px;
  color: var(--text-secondary);
}

/* Accessibility Focus Visible */
button:focus-visible,
a:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
}

/* ==========================================================================
   RESPONSIVE DESIGN (375px, 390px, 430px, 768px, 1024px, 1440px)
   ========================================================================== */

/* Tablet & Smaller (<= 1024px) */
@media (max-width: 1024px) {
  .footer-top-grid {
    grid-template-columns: 1fr 1fr;
    gap: 36px;
  }

  .footer-brand-col {
    grid-column: span 2;
  }

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

  .layer-bar:nth-child(2) { margin-left: 16px; }
  .layer-bar:nth-child(3) { margin-left: 32px; }
  .layer-bar:nth-child(4) { margin-left: 48px; }
}

/* Mobile & Small Tablet (<= 768px) */
@media (max-width: 768px) {
  :root {
    --header-height: 60px;
  }

  .nav-links,
  .system-status {
    display: none;
  }

  .mobile-menu-btn {
    display: inline-flex;
  }

  .system-summary-strip {
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
  }

  .summary-item:nth-child(2)::after {
    display: none;
  }

  .network-matrix {
    grid-template-columns: 1fr;
  }

  /* Reset Layer Stack progressive indents on mobile to avoid overflow */
  .layer-bar,
  .layer-bar:nth-child(1),
  .layer-bar:nth-child(2),
  .layer-bar:nth-child(3),
  .layer-bar:nth-child(4) {
    margin-left: 0;
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }

  .layer-left {
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
  }

  .ai-pipeline-wire {
    flex-direction: column;
    align-items: flex-start;
    gap: 20px;
  }

  .wire-track {
    display: none;
  }

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

  .tier-strip {
    flex-direction: column;
    align-items: flex-start;
    gap: 16px;
  }

  .tier-features {
    padding: 0;
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }

  .tier-price-cta {
    width: 100%;
    justify-content: space-between;
  }

  .knowledge-nodes-mesh,
  .field-signals-grid,
  .sitemap-grid {
    grid-template-columns: 1fr;
  }

  .category-node-row {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }

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

  .footer-brand-col {
    grid-column: span 1;
  }

  .footer-bottom-strip {
    flex-direction: column;
    gap: 14px;
    align-items: flex-start;
  }
}

/* Small Screen Phones (375px - 430px) */
@media (max-width: 430px) {
  .hero-brand-name {
    font-size: 2.3rem;
  }

  .hero-slogan {
    font-size: 1.7rem;
  }

  .hero-h1-sub {
    font-size: 1.1rem;
  }

  .hero-cta-group {
    flex-direction: column;
    width: 100%;
  }

  .hero-cta-group .btn {
    width: 100%;
  }

  .system-summary-strip {
    grid-template-columns: 1fr;
    text-align: left;
  }

  .summary-item {
    align-items: flex-start;
  }

  .summary-item:not(:last-child)::after {
    display: none;
  }

  .channel-row {
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
    padding: 18px 20px;
  }

  .device-row {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
    padding: 16px;
  }

  .matrix-quadrant {
    padding: 24px 20px;
  }

  .faq-trigger {
    padding: 18px 20px;
    font-size: 0.95rem;
  }

  .faq-body {
    padding: 0 20px 18px 20px;
  }

  .article-author-strip {
    width: 100%;
  }
}

/* Reduced Motion for Accessibility */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

  .wire-pulse {
    animation: none;
    display: none;
  }
}