/* Zenith AI - Design System */
/* Clean, minimal, premium aesthetic */

:root {
  /* Colors - Minimal dark theme with subtle accents */
  --color-bg-primary: #09090b;
  --color-bg-secondary: #18181b;
  --color-bg-tertiary: #27272a;
  --color-text-primary: #fafafa;
  --color-text-secondary: #a1a1aa;
  --color-text-muted: #71717a;
  --color-accent: #6366f1;
  --color-accent-hover: #4f46e5;
  --color-border: #27272a;
  --color-border-light: #3f3f46;
  
  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;
  --space-4xl: 6rem;
  
  /* Typography */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  --font-size-5xl: 3rem;
  
  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 200ms ease;
  --transition-slow: 300ms ease;
  
  /* Container */
  --container-max: 1200px;
  --container-padding: 1.5rem;
}

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

/* Base */
html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  background-color: var(--color-bg-primary);
  color: var(--color-text-primary);
  line-height: 1.6;
  min-height: 100vh;
}

/* Container */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

h1 { font-size: var(--font-size-5xl); }
h2 { font-size: var(--font-size-4xl); }
h3 { font-size: var(--font-size-3xl); }
h4 { font-size: var(--font-size-2xl); }
h5 { font-size: var(--font-size-xl); }
h6 { font-size: var(--font-size-lg); }

p {
  color: var(--color-text-secondary);
  line-height: 1.7;
}

a {
  color: inherit;
  text-decoration: none;
}

/* Navigation */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(9, 9, 11, 0.8);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4rem;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-weight: 700;
  font-size: var(--font-size-lg);
}

.nav-logo-icon {
  width: 2rem;
  height: 2rem;
  background: linear-gradient(135deg, var(--color-accent), #a855f7);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  color: white;
}

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

.nav-link {
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
}

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

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-lg);
  font-size: var(--font-size-sm);
  font-weight: 600;
  border-radius: var(--radius-lg);
  border: none;
  cursor: pointer;
  transition: all var(--transition-base);
  text-decoration: none;
}

.btn-primary {
  background: var(--color-accent);
  color: white;
}

.btn-primary:hover {
  background: var(--color-accent-hover);
  transform: translateY(-1px);
}

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

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

.btn-app-store {
  background: var(--color-text-primary);
  color: var(--color-bg-primary);
}

.btn-app-store:hover {
  opacity: 0.9;
}

/* Hero Section */
.hero {
  padding: 8rem 0 4rem;
  text-align: center;
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  background: rgba(99, 102, 241, 0.1);
  border: 1px solid rgba(99, 102, 241, 0.2);
  border-radius: 9999px;
  font-size: var(--font-size-xs);
  font-weight: 600;
  color: var(--color-accent);
  margin-bottom: var(--space-lg);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.hero-title {
  font-size: clamp(2.5rem, 5vw, 4rem);
  font-weight: 700;
  max-width: 800px;
  margin: 0 auto var(--space-lg);
}

.hero-subtitle {
  font-size: var(--font-size-xl);
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 0 auto var(--space-2xl);
}

.hero-cta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-md);
  flex-wrap: wrap;
}

.hero-visual {
  margin-top: var(--space-3xl);
  position: relative;
}

/* Before/After Comparison */
.before-after {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md);
  max-width: 900px;
  margin: var(--space-3xl) auto;
}

.before-after-item {
  position: relative;
  border-radius: var(--radius-xl);
  overflow: hidden;
  background: var(--color-bg-secondary);
}

.before-after-label {
  position: absolute;
  top: var(--space-md);
  left: var(--space-md);
  padding: var(--space-xs) var(--space-sm);
  background: rgba(0, 0, 0, 0.7);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.before-after-image {
  width: 100%;
  aspect-ratio: 1;
  object-fit: cover;
}

/* Features Grid */
.features {
  padding: var(--space-4xl) 0;
}

.features-header {
  text-align: center;
  margin-bottom: var(--space-3xl);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-lg);
}

.feature-card {
  padding: var(--space-xl);
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  transition: all var(--transition-base);
}

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

.feature-icon {
  width: 3rem;
  height: 3rem;
  background: linear-gradient(135deg, var(--color-accent), #a855f7);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-md);
  font-size: var(--font-size-xl);
}

.feature-title {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: var(--space-sm);
}

.feature-description {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
}

/* Use Cases */
.use-cases {
  padding: var(--space-4xl) 0;
  background: var(--color-bg-secondary);
}

.use-cases-header {
  text-align: center;
  margin-bottom: var(--space-3xl);
}

.use-cases-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-md);
}

.use-case-item {
  padding: var(--space-lg);
  background: var(--color-bg-primary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  text-align: center;
  font-weight: 500;
  transition: all var(--transition-base);
}

.use-case-item:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* Platforms */
.platforms {
  padding: var(--space-4xl) 0;
}

.platforms-header {
  text-align: center;
  margin-bottom: var(--space-3xl);
}

.platforms-grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-xl);
}

.platform-item {
  padding: var(--space-md) var(--space-xl);
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  font-weight: 600;
  color: var(--color-text-secondary);
}

/* CTA Section */
.cta-section {
  padding: var(--space-4xl) 0;
  text-align: center;
}

.cta-title {
  font-size: var(--font-size-3xl);
  margin-bottom: var(--space-md);
}

.cta-subtitle {
  font-size: var(--font-size-lg);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-xl);
}

/* FAQ */
.faq {
  padding: var(--space-4xl) 0;
  background: var(--color-bg-secondary);
}

.faq-header {
  text-align: center;
  margin-bottom: var(--space-3xl);
}

.faq-list {
  max-width: 700px;
  margin: 0 auto;
}

.faq-item {
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-lg) 0;
}

.faq-question {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: var(--space-sm);
}

.faq-answer {
  color: var(--color-text-secondary);
  font-size: var(--font-size-base);
}

/* Footer */
.footer {
  padding: var(--space-3xl) 0;
  border-top: 1px solid var(--color-border);
}

.footer-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-lg);
  text-align: center;
}

.footer-links {
  display: flex;
  gap: var(--space-xl);
  flex-wrap: wrap;
  justify-content: center;
}

.footer-link {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  transition: color var(--transition-fast);
}

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

.footer-copyright {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
}

/* Language Selector */
.lang-selector {
  position: relative;
}

.lang-selector select {
  appearance: none;
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-sm) var(--space-xl) var(--space-sm) var(--space-md);
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  cursor: pointer;
}

/* Section spacing */
.section {
  padding: var(--space-4xl) 0;
}

/* Mobile Responsive */
@media (max-width: 768px) {
  :root {
    --container-padding: 1rem;
  }
  
  h1 { font-size: var(--font-size-4xl); }
  h2 { font-size: var(--font-size-3xl); }
  
  .nav-links {
    display: none;
  }
  
  .hero {
    padding: 6rem 0 3rem;
  }
  
  .before-after {
    grid-template-columns: 1fr;
  }
  
  .hero-cta {
    flex-direction: column;
  }
  
  .features-grid {
    grid-template-columns: 1fr;
  }
}

/* Accessibility */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

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