/* ============================================
   CSS Variables & Reset
   ============================================ */
:root {
  --bg-primary: #060912;
  --bg-secondary: #0c1120;
  --bg-card: rgba(18, 24, 40, 0.6);
  --bg-card-hover: rgba(24, 32, 52, 0.8);
  --border-glow: rgba(0, 212, 255, 0.15);
  --border-glow-strong: rgba(0, 212, 255, 0.4);
  --text-primary: #e8eef8;
  --text-secondary: #9aabc7;
  --text-muted: #5a6b88;
  --accent-cyan: #00d4ff;
  --accent-blue: #4a9eff;
  --accent-purple: #7c5cff;
  --accent-warm: #ff8a5c;
  --gradient-cyan: linear-gradient(135deg, #00d4ff 0%, #4a9eff 100%);
  --gradient-purple: linear-gradient(135deg, #7c5cff 0%, #00d4ff 100%);
  --gradient-text: linear-gradient(135deg, #00d4ff 0%, #7c5cff 100%);
  --font-display: 'Space Grotesk', sans-serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --nav-height: 70px;
  --max-width: 1200px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
}

body {
  font-family: var(--font-body);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

/* ============================================
   Particle Canvas
   ============================================ */
#particle-canvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  pointer-events: none;
}

/* ============================================
   Navigation
   ============================================ */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--nav-height);
  z-index: 1000;
  background: rgba(6, 9, 18, 0.7);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(0, 212, 255, 0.08);
  transition: all 0.3s ease;
}

.navbar.scrolled {
  background: rgba(6, 9, 18, 0.92);
  border-bottom-color: rgba(0, 212, 255, 0.2);
}

.nav-container {
  max-width: var(--max-width);
  height: 100%;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 2rem;
}

.nav-logo {
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
  text-decoration: none;
  font-family: var(--font-display);
  font-weight: 600;
}

.logo-k {
  font-size: 1.8rem;
  font-style: italic;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.logo-text {
  font-size: 1rem;
  color: var(--text-secondary);
  letter-spacing: 0.05em;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 2rem;
}

.nav-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 500;
  transition: color 0.2s;
  position: relative;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gradient-cyan);
  transition: width 0.3s;
}

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

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

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

.lang-toggle {
  background: rgba(0, 212, 255, 0.08);
  border: 1px solid rgba(0, 212, 255, 0.2);
  color: var(--accent-cyan);
  padding: 0.4rem 1rem;
  border-radius: 20px;
  cursor: pointer;
  font-family: var(--font-body);
  font-size: 0.85rem;
  font-weight: 500;
  transition: all 0.2s;
}

.lang-toggle:hover {
  background: rgba(0, 212, 255, 0.15);
  border-color: rgba(0, 212, 255, 0.5);
}

.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
}

.mobile-menu-toggle span {
  width: 24px;
  height: 2px;
  background: var(--text-primary);
  transition: all 0.3s;
}

/* ============================================
   Layout Helpers
   ============================================ */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 2rem;
  position: relative;
  z-index: 1;
}

.section {
  padding: 6rem 0;
  position: relative;
  z-index: 1;
}

.section-alt {
  background: linear-gradient(180deg, transparent 0%, rgba(12, 17, 32, 0.5) 50%, transparent 100%);
}

.section-header {
  margin-bottom: 3.5rem;
  position: relative;
}

.section-number {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent-cyan);
  opacity: 0.6;
  display: block;
  margin-bottom: 0.5rem;
}

.section-title {
  font-family: var(--font-display);
  font-size: 2.25rem;
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.section-line {
  width: 60px;
  height: 3px;
  background: var(--gradient-cyan);
  margin-top: 1rem;
  border-radius: 2px;
}

.section-intro {
  font-size: 1.05rem;
  color: var(--text-secondary);
  max-width: 760px;
  margin-bottom: 3rem;
  line-height: 1.8;
}

/* ============================================
   Content Grids
   ============================================ */
.content-grid {
  display: grid;
  gap: 2rem;
  margin-bottom: 3rem;
}

.two-col {
  grid-template-columns: 1fr 1fr;
}

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

.content-text {
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.9;
}

.content-text p {
  margin-bottom: 1rem;
}

.content-text strong {
  color: var(--text-primary);
  font-weight: 600;
}

.content-text em {
  color: var(--accent-cyan);
  font-style: italic;
}

.content-card {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 16px;
  padding: 2rem;
  transition: all 0.3s;
}

.content-card h3 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  color: var(--accent-cyan);
  margin-bottom: 1rem;
}

.content-card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.8;
}

/* ============================================
   Hero Section
   ============================================ */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  position: relative;
  z-index: 1;
  padding-top: var(--nav-height);
}

.hero-grid-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-image:
    linear-gradient(rgba(0, 212, 255, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 212, 255, 0.03) 1px, transparent 1px);
  background-size: 60px 60px;
  z-index: -1;
  mask-image: radial-gradient(ellipse at center, black 0%, transparent 70%);
  -webkit-mask-image: radial-gradient(ellipse at center, black 0%, transparent 70%);
}

.hero-content {
  max-width: 800px;
  padding: 0 2rem;
}

.hero-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--accent-cyan);
  background: rgba(0, 212, 255, 0.08);
  border: 1px solid rgba(0, 212, 255, 0.2);
  padding: 0.4rem 1.2rem;
  border-radius: 20px;
  margin-bottom: 2rem;
  opacity: 0;
  animation: fadeInUp 0.8s ease 0.2s forwards;
}

.hero-constant {
  font-family: var(--font-display);
  margin-bottom: 1.5rem;
  opacity: 0;
  animation: fadeInUp 0.8s ease 0.4s forwards;
}

.constant-mantissa {
  font-size: clamp(2.5rem, 8vw, 5rem);
  font-weight: 700;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.02em;
}

.constant-exponent {
  font-size: clamp(1.5rem, 4vw, 2.5rem);
  color: var(--text-secondary);
  font-weight: 400;
  margin-left: 0.3rem;
}

.constant-exponent sup {
  font-size: 0.65em;
}

.constant-unit {
  display: block;
  font-size: clamp(1rem, 2.5vw, 1.5rem);
  color: var(--accent-cyan);
  letter-spacing: 0.1em;
  margin-top: 0.5rem;
}

.hero-title {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 5vw, 3rem);
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
  opacity: 0;
  animation: fadeInUp 0.8s ease 0.6s forwards;
}

.hero-subtitle {
  font-size: clamp(1rem, 2vw, 1.25rem);
  color: var(--text-secondary);
  max-width: 580px;
  margin: 0 auto;
  opacity: 0;
  animation: fadeInUp 0.8s ease 0.8s forwards;
}

.hero-scroll {
  margin-top: 4rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  opacity: 0;
  animation: fadeInUp 0.8s ease 1s forwards;
}

.scroll-line {
  width: 1px;
  height: 50px;
  background: linear-gradient(to bottom, var(--accent-cyan), transparent);
  animation: scrollLine 2s ease-in-out infinite;
}

@keyframes scrollLine {
  0%, 100% { transform: scaleY(0.3); transform-origin: top; }
  50% { transform: scaleY(1); transform-origin: top; }
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ============================================
   Stat Cards
   ============================================ */
.stat-cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  margin-top: 3rem;
}

.stat-card {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 16px;
  padding: 2rem;
  text-align: center;
  transition: all 0.3s;
}

.stat-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-glow-strong);
  transform: translateY(-4px);
}

.stat-value {
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 700;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.5rem;
}

.stat-label {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent-cyan);
  margin-bottom: 0.5rem;
}

.stat-desc {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* ============================================
   Formula Section
   ============================================ */
.formula-display {
  text-align: center;
  margin-bottom: 3rem;
}

.formula-equation {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--font-display);
  font-size: clamp(2.5rem, 6vw, 4rem);
  font-style: italic;
  padding: 2rem 3rem;
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 20px;
  box-shadow: 0 0 60px rgba(0, 212, 255, 0.1);
}

.var-s { color: var(--accent-cyan); font-weight: 600; }
.eq { color: var(--text-muted); font-style: normal; }
.var-k { color: var(--accent-purple); font-weight: 600; }
.ln { color: var(--text-secondary); font-style: normal; font-size: 0.8em; }
.var-w { color: var(--accent-warm); font-weight: 600; }

.formula-card {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 16px;
  padding: 2rem;
  text-align: center;
  transition: all 0.3s;
}

.formula-card:hover {
  border-color: var(--border-glow-strong);
  transform: translateY(-4px);
}

.formula-symbol {
  font-family: var(--font-display);
  font-size: 3rem;
  font-style: italic;
  font-weight: 700;
  margin-bottom: 1rem;
}

.formula-card:nth-child(1) .formula-symbol { color: var(--accent-cyan); }
.formula-card:nth-child(2) .formula-symbol { color: var(--accent-purple); }
.formula-card:nth-child(3) .formula-symbol { color: var(--accent-warm); }

.formula-card h3 {
  font-family: var(--font-display);
  font-size: 1.1rem;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
}

.formula-card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.formula-note {
  margin-top: 2rem;
  padding: 1.5rem 2rem;
  background: rgba(0, 212, 255, 0.04);
  border-left: 3px solid var(--accent-cyan);
  border-radius: 0 12px 12px 0;
}

.formula-note p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.8;
}

.formula-note strong {
  color: var(--accent-cyan);
}

/* ============================================
   Bridge Section
   ============================================ */
.bridge-visual {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 2rem;
  align-items: center;
  margin-bottom: 3rem;
  padding: 3rem 2rem;
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 20px;
}

.bridge-side {
  text-align: center;
}

.bridge-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.bridge-side h3 {
  font-family: var(--font-display);
  font-size: 1.3rem;
  color: var(--accent-cyan);
  margin-bottom: 1.5rem;
}

.bridge-side ul {
  list-style: none;
  text-align: left;
}

.bridge-side ul li {
  color: var(--text-secondary);
  font-size: 0.9rem;
  padding: 0.5rem 0;
  border-bottom: 1px solid rgba(0, 212, 255, 0.06);
}

.bridge-side ul li:last-child {
  border-bottom: none;
}

.bridge-center {
  text-align: center;
}

.bridge-constant {
  font-family: var(--font-display);
  font-size: 4rem;
  font-style: italic;
  font-weight: 700;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: pulse 3s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { transform: scale(1); opacity: 1; }
  50% { transform: scale(1.08); opacity: 0.85; }
}

.bridge-arrows {
  display: flex;
  justify-content: center;
  gap: 1rem;
  font-size: 1.5rem;
  color: var(--accent-cyan);
  margin: 1rem 0;
}

.bridge-label {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-muted);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.relation-box {
  text-align: center;
  padding: 2.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 16px;
}

.relation-label {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--accent-cyan);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 1rem;
}

.relation-equation {
  font-family: var(--font-display);
  font-size: 2rem;
  font-style: italic;
  color: var(--text-primary);
  margin-bottom: 1rem;
}

.relation-box p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  max-width: 600px;
  margin: 0 auto;
}

/* ============================================
   Timeline
   ============================================ */
.timeline {
  position: relative;
  max-width: 900px;
  margin: 0 auto;
  padding-left: 2rem;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 80px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: linear-gradient(to bottom, var(--accent-cyan), var(--accent-purple), transparent);
  opacity: 0.3;
}

.timeline-item {
  display: grid;
  grid-template-columns: 80px 1fr;
  gap: 2rem;
  padding-bottom: 2.5rem;
  position: relative;
}

.timeline-year {
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 600;
  color: var(--accent-cyan);
  text-align: right;
  padding-top: 0.2rem;
}

.timeline-dot {
  position: absolute;
  left: 73px;
  top: 0.5rem;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--bg-primary);
  border: 2px solid var(--accent-cyan);
  z-index: 2;
}

.timeline-dot::after {
  content: '';
  position: absolute;
  top: 2px;
  left: 2px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent-cyan);
}

.timeline-dot-end {
  border-color: var(--accent-warm);
}

.timeline-dot-end::after {
  background: var(--accent-warm);
}

.timeline-content {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 12px;
  padding: 1.5rem;
  transition: all 0.3s;
}

.timeline-content:hover {
  border-color: var(--border-glow-strong);
  transform: translateX(4px);
}

.timeline-content h3 {
  font-family: var(--font-display);
  font-size: 1.1rem;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.timeline-content p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.7;
}

/* ============================================
   SI Redefinition
   ============================================ */
.redef-date {
  text-align: center;
  margin-bottom: 3rem;
  font-family: var(--font-display);
  display: flex;
  align-items: baseline;
  justify-content: center;
  gap: 0.8rem;
}

.redef-day {
  font-size: 4rem;
  font-weight: 700;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.redef-month {
  font-size: 1.5rem;
  color: var(--text-secondary);
}

.redef-year {
  font-size: 1.5rem;
  color: var(--accent-cyan);
}

.redef-comparison {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 1.5rem;
  align-items: center;
  margin-bottom: 3rem;
}

.redef-old, .redef-new {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 16px;
  padding: 2rem;
  transition: all 0.3s;
}

.redef-new {
  border-color: var(--border-glow-strong);
  box-shadow: 0 0 30px rgba(0, 212, 255, 0.08);
}

.redef-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 0.3rem 0.8rem;
  border-radius: 12px;
  margin-bottom: 1rem;
}

.redef-old .redef-badge {
  background: rgba(255, 138, 92, 0.1);
  color: var(--accent-warm);
  border: 1px solid rgba(255, 138, 92, 0.2);
}

.redef-new .redef-badge {
  background: rgba(0, 212, 255, 0.1);
  color: var(--accent-cyan);
  border: 1px solid rgba(0, 212, 255, 0.2);
}

.redef-old h3, .redef-new h3 {
  font-family: var(--font-display);
  font-size: 1.2rem;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
}

.redef-old p, .redef-new p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.7;
}

.redef-arrow {
  font-size: 2rem;
  color: var(--accent-cyan);
  text-align: center;
}

.redef-methods {
  text-align: center;
  padding: 2rem;
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 16px;
}

.redef-methods h3 {
  font-family: var(--font-display);
  font-size: 1.1rem;
  color: var(--text-primary);
  margin-bottom: 1.5rem;
}

.method-tags {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.75rem;
}

.method-tag {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--accent-cyan);
  background: rgba(0, 212, 255, 0.06);
  border: 1px solid rgba(0, 212, 255, 0.15);
  padding: 0.5rem 1rem;
  border-radius: 20px;
}

/* ============================================
   Applications
   ============================================ */
.app-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

.app-card {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 16px;
  padding: 2rem;
  transition: all 0.3s;
  display: flex;
  flex-direction: column;
}

.app-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-glow-strong);
  transform: translateY(-6px);
  box-shadow: 0 10px 40px rgba(0, 212, 255, 0.1);
}

.app-icon {
  font-size: 2.5rem;
  margin-bottom: 1rem;
}

.app-card h3 {
  font-family: var(--font-display);
  font-size: 1.15rem;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
}

.app-card p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.7;
  flex-grow: 1;
  margin-bottom: 1rem;
}

.app-formula {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent-cyan);
  background: rgba(0, 212, 255, 0.05);
  border-radius: 8px;
  padding: 0.6rem 0.8rem;
  text-align: center;
  border: 1px solid rgba(0, 212, 255, 0.1);
}

/* ============================================
   Legacy
   ============================================ */
.legacy-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  margin-bottom: 3rem;
}

.legacy-text {
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.9;
}

.legacy-text p {
  margin-bottom: 1rem;
}

.legacy-text strong {
  color: var(--text-primary);
}

.legacy-quote {
  position: relative;
  padding: 3rem 2rem;
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 20px;
  text-align: center;
  margin-bottom: 3rem;
}

.quote-mark {
  font-family: var(--font-display);
  font-size: 5rem;
  color: var(--accent-cyan);
  opacity: 0.2;
  position: absolute;
  top: 0.5rem;
  left: 1.5rem;
  line-height: 1;
}

.legacy-quote p {
  font-size: 1.2rem;
  color: var(--text-primary);
  font-style: italic;
  line-height: 1.8;
  max-width: 700px;
  margin: 0 auto 1rem;
}

.quote-author {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--accent-cyan);
}

.legacy-tombstone {
  text-align: center;
  padding: 3rem;
  background: linear-gradient(135deg, rgba(0, 212, 255, 0.05), rgba(124, 92, 255, 0.05));
  border: 1px solid var(--border-glow);
  border-radius: 20px;
}

.tombstone-equation {
  font-family: var(--font-display);
  font-size: 3rem;
  font-style: italic;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 1rem;
}

.tombstone-desc {
  color: var(--text-secondary);
  font-size: 0.95rem;
  max-width: 500px;
  margin: 0 auto;
}

/* ============================================
   Footer
   ============================================ */
.footer {
  background: rgba(6, 9, 18, 0.8);
  border-top: 1px solid rgba(0, 212, 255, 0.1);
  padding: 3rem 0 2rem;
  position: relative;
  z-index: 1;
}

.footer-content {
  display: grid;
  grid-template-columns: 1fr 2fr 1fr;
  gap: 2rem;
  align-items: center;
  margin-bottom: 2rem;
}

.footer-brand {
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
  font-family: var(--font-display);
  font-weight: 600;
}

.footer-k {
  font-size: 2rem;
  font-style: italic;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.footer-domain {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.footer-desc {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.7;
}

.footer-links {
  display: flex;
  gap: 1.5rem;
  justify-content: flex-end;
}

.footer-links a {
  font-size: 0.85rem;
  color: var(--text-secondary);
  text-decoration: none;
  transition: color 0.2s;
}

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

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 2rem;
  border-top: 1px solid rgba(0, 212, 255, 0.08);
  font-size: 0.8rem;
  color: var(--text-muted);
}

.footer-constant {
  font-family: var(--font-mono);
  color: var(--accent-cyan);
  opacity: 0.7;
}

/* ============================================
   Reveal Animation
   ============================================ */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 900px) {
  .nav-links {
    display: none;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    width: 100%;
    flex-direction: column;
    background: rgba(6, 9, 18, 0.98);
    backdrop-filter: blur(20px);
    padding: 1.5rem 2rem;
    gap: 1rem;
    border-bottom: 1px solid rgba(0, 212, 255, 0.1);
  }

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

  .mobile-menu-toggle {
    display: flex;
  }

  .mobile-menu-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
  }
  .mobile-menu-toggle.active span:nth-child(2) {
    opacity: 0;
  }
  .mobile-menu-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -6px);
  }

  .two-col, .three-col {
    grid-template-columns: 1fr;
  }

  .stat-cards {
    grid-template-columns: 1fr;
  }

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

  .bridge-visual {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .bridge-center {
    order: 2;
  }

  .bridge-micro {
    order: 3;
  }

  .bridge-side ul {
    text-align: center;
  }

  .redef-comparison {
    grid-template-columns: 1fr;
  }

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

  .legacy-content {
    grid-template-columns: 1fr;
  }

  .footer-content {
    grid-template-columns: 1fr;
    text-align: center;
    gap: 1.5rem;
  }

  .footer-links {
    justify-content: center;
  }

  .footer-bottom {
    flex-direction: column;
    gap: 0.5rem;
    text-align: center;
  }

  .section {
    padding: 4rem 0;
  }

  .section-title {
    font-size: 1.75rem;
  }

  .container {
    padding: 0 1.5rem;
  }

  .timeline {
    padding-left: 0;
  }

  .timeline::before {
    left: 60px;
  }

  .timeline-item {
    grid-template-columns: 60px 1fr;
    gap: 1rem;
  }

  .timeline-dot {
    left: 53px;
  }

  .formula-equation {
    padding: 1.5rem 2rem;
  }
}

@media (max-width: 500px) {
  .hero-constant {
    font-size: 0.85em;
  }

  .section-title {
    font-size: 1.4rem;
  }

  .nav-container {
    padding: 0 1rem;
  }

  .logo-text {
    display: none;
  }
}