:root {
  /* Primary Colors - Clean Blue */
  --primary: #0066FF;
  --primary-dark: #0052CC;
  --primary-light: #3385FF;
  --primary-hover: #0052CC;
  
  /* Accent */
  --accent: #00D4FF;
  --accent-dark: #00B8E6;
  
  /* Backgrounds - Light Mode First */
  --bg-primary: #FFFFFF;
  --bg-secondary: #F7F9FC;
  --bg-tertiary: #EDF2F7;
  --bg-elevated: #FFFFFF;
  
  /* Text Colors */
  --text-primary: #0F1419;
  --text-secondary: #536471;
  --text-tertiary: #8899A6;
  
  /* Borders */
  --border: #E7ECF0;
  --border-strong: #D1D9E0;
  
  /* Status Colors */
  --success: #00BA88;
  --error: #F04438;
  --warning: #F79009;
  --info: #0066FF;
  
  /* Shadows */
  --shadow-xs: 0 1px 2px rgba(15, 20, 25, 0.04);
  --shadow-sm: 0 2px 4px rgba(15, 20, 25, 0.06);
  --shadow-md: 0 4px 8px rgba(15, 20, 25, 0.08);
  --shadow-lg: 0 8px 16px rgba(15, 20, 25, 0.10);
  --shadow-xl: 0 16px 32px rgba(15, 20, 25, 0.12);
  
  /* Border Radius */
  --radius-sm: 6px;
  --radius: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;
  
  /* Spacing */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  --space-3xl: 64px;
  
  /* Transitions - Sui.io Style */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 200ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 300ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* Dark Mode */
@media (prefers-color-scheme: dark) {
  :root {
    --bg-primary: #000000;
    --bg-secondary: #0A0A0A;
    --bg-tertiary: #141414;
    --bg-elevated: #1A1A1A;
    
    --text-primary: #FFFFFF;
    --text-secondary: #A8B0B8;
    --text-tertiary: #6B7280;
    
    --border: #1F1F1F;
    --border-strong: #2A2A2A;
  }
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Helvetica Neue', sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color var(--transition-smooth), color var(--transition-smooth);
}

.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

/* Header */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid var(--border);
  transition: all var(--transition-base);
}

@media (prefers-color-scheme: dark) {
  .header {
    background: rgba(0, 0, 0, 0.8);
  }
}

.header.scrolled {
  box-shadow: var(--shadow-sm);
}

.header-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
  transition: height var(--transition-base);
}

.logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 18px;
  font-weight: 600;
  color: var(--text-primary);
  text-decoration: none;
  transition: opacity var(--transition-fast);
}

.logo:hover {
  opacity: 0.8;
}

.logo svg {
  flex-shrink: 0;
  transition: transform var(--transition-base);
}

.logo:hover svg {
  transform: scale(1.05);
}

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

.nav-link {
  position: relative;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 15px;
  font-weight: 500;
  transition: color var(--transition-fast);
  padding: 8px 0;
}

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

.nav-link.active {
  color: var(--primary);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  background: var(--primary);
  border-radius: var(--radius-full);
  animation: slide-in-bottom var(--transition-base);
}

@keyframes slide-in-bottom {
  from {
    width: 0;
    left: 50%;
  }
  to {
    width: 100%;
    left: 0;
  }
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: 12px 24px;
  border: none;
  border-radius: var(--radius);
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-base);
  text-decoration: none;
  white-space: nowrap;
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.1);
  transform: translate(-50%, -50%);
  transition: width var(--transition-smooth), height var(--transition-smooth);
}

.btn:hover::before {
  width: 300px;
  height: 300px;
}

.btn-primary {
  background: var(--primary);
  color: white;
  box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
  background: var(--primary-hover);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.btn-primary:active {
  transform: translateY(0);
  box-shadow: var(--shadow-sm);
}

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

.btn-secondary:hover {
  background: var(--bg-tertiary);
  border-color: var(--border-strong);
  transform: translateY(-1px);
}

.btn-outline {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border);
}

.btn-outline:hover {
  background: var(--bg-secondary);
  border-color: var(--border-strong);
}

.btn-sm {
  padding: 8px 16px;
  font-size: 14px;
}

.btn-lg {
  padding: 16px 32px;
  font-size: 16px;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none !important;
}

.btn svg {
  transition: transform var(--transition-base);
}

.btn:hover svg {
  transform: translateX(2px);
}

/* Typography */
.section-title {
  font-size: 48px;
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin-bottom: var(--space-md);
  text-align: center;
  color: var(--text-primary);
  animation: fade-in-up var(--transition-smooth);
}

.section-subtitle {
  font-size: 20px;
  color: var(--text-secondary);
  text-align: center;
  margin-bottom: var(--space-2xl);
  line-height: 1.6;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
  animation: fade-in-up var(--transition-smooth) 100ms;
}

/* Footer */
.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border);
  padding: var(--space-3xl) 0 var(--space-xl);
  margin-top: 120px;
  transition: background-color var(--transition-smooth);
}

.footer-content {
  display: grid;
  grid-template-columns: 2fr repeat(3, 1fr);
  gap: var(--space-3xl);
  margin-bottom: var(--space-2xl);
}

.footer-section h4 {
  font-size: 14px;
  font-weight: 600;
  margin-bottom: var(--space-md);
  color: var(--text-primary);
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

.footer-section a {
  display: block;
  color: var(--text-secondary);
  text-decoration: none;
  margin-bottom: var(--space-sm);
  font-size: 15px;
  transition: color var(--transition-fast), transform var(--transition-fast);
}

.footer-section a:hover {
  color: var(--primary);
  transform: translateX(2px);
}

.footer-section p {
  color: var(--text-secondary);
  font-size: 15px;
  line-height: 1.6;
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 18px;
  font-weight: 600;
  margin-bottom: var(--space-md);
  color: var(--text-primary);
}

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: var(--space-xl);
  border-top: 1px solid var(--border);
  color: var(--text-tertiary);
  font-size: 14px;
}

.footer-bottom p {
  margin: 0;
  transition: color var(--transition-fast);
}

/* Utility Classes */
.hidden {
  display: none !important;
}

.gradient-text {
  background: linear-gradient(135deg, var(--primary) 0%, var(--accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: gradient-shift 3s ease infinite;
  background-size: 200% 200%;
}

@keyframes gradient-shift {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

/* Responsive */
@media (max-width: 1024px) {
  .container {
    padding: 0 var(--space-lg);
  }
  
  .footer-content {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .header-content {
    height: 64px;
  }
  
  .nav {
    gap: var(--space-md);
  }
  
  .nav-link {
    font-size: 14px;
  }
  
  .section-title {
    font-size: 36px;
  }
  
  .section-subtitle {
    font-size: 18px;
  }
  
  .footer-content {
    grid-template-columns: 1fr;
    gap: var(--space-xl);
  }
  
  .footer-bottom {
    flex-direction: column;
    gap: var(--space-sm);
    text-align: center;
  }
}

/* Animations */
@keyframes fade-in {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fade-in-up {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in {
  animation: fade-in var(--transition-smooth);
}

/* Smooth Scroll */
html {
  scroll-behavior: smooth;
}

/* Selection */
::selection {
  background: var(--primary);
  color: white;
}

::-moz-selection {
  background: var(--primary);
  color: white;
}