/* Critical CSS - Above the fold content for Russian version
   Optimized for fast initial render */

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

:root {
  /* Color palette */
  --color-primary: #4f46e5;
  --color-primary-dark: #4338ca;
  --color-primary-light: #6366f1;
  --color-accent: #06b6d4;
  --color-accent-dark: #0891b2;
  --color-success: #10b981;
  --color-warning: #f59e0b;
  --color-danger: #ef4444;
  
  /* Neutral colors */
  --color-slate-50: #f8fafc;
  --color-slate-100: #f1f5f9;
  --color-slate-200: #e2e8f0;
  --color-slate-300: #cbd5e1;
  --color-slate-400: #94a3b8;
  --color-slate-500: #64748b;
  --color-slate-600: #475569;
  --color-slate-700: #334155;
  --color-slate-800: #1e293b;
  --color-slate-900: #0f172a;
  
  /* Gradients */
  --gradient-primary: linear-gradient(135deg, #4f46e5 0%, #06b6d4 100%);
  --gradient-hero: linear-gradient(135deg, #f8fafc 0%, #e0e7ff 100%);
  
  /* Typography */
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', 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;
  --font-size-6xl: 3.75rem;
  
  /* Spacing */
  --spacing-1: 0.25rem;
  --spacing-2: 0.5rem;
  --spacing-3: 0.75rem;
  --spacing-4: 1rem;
  --spacing-5: 1.25rem;
  --spacing-6: 1.5rem;
  --spacing-8: 2rem;
  --spacing-10: 2.5rem;
  --spacing-12: 3rem;
  --spacing-16: 4rem;
  --spacing-20: 5rem;
  --spacing-24: 6rem;
  
  /* Border radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  --radius-3xl: 2rem;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
  
  /* Transitions */
  --transition-fast: 150ms ease-in-out;
  --transition-base: 200ms ease-in-out;
  --transition-slow: 300ms ease-in-out;
}

/* Base styles */
html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

body {
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--color-slate-800);
  background-color: var(--color-slate-50);
  margin: 0;
  padding: 0;
}

/* Header - Critical above the fold */
header {
  position: sticky;
  top: 0;
  z-index: 40;
  background-color: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-slate-200);
  box-shadow: var(--shadow-sm);
}

.header .container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--spacing-4);
}

.header nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-4) 0;
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-3);
  text-decoration: none;
  color: inherit;
}

.logo-icon {
  width: 2.5rem;
  height: 2.5rem;
  border-radius: var(--radius-xl);
  background: var(--gradient-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 700;
  font-size: var(--font-size-lg);
  box-shadow: var(--shadow-lg);
}

.logo span {
  font-size: var(--font-size-xl);
  font-weight: 800;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Navigation */
.nav-links {
  display: none;
  list-style: none;
  gap: var(--spacing-2);
}

.nav-link {
  padding: var(--spacing-2) var(--spacing-4);
  border-radius: var(--radius-xl);
  text-decoration: none;
  color: var(--color-slate-700);
  font-weight: 500;
  transition: background-color var(--transition-base);
}

.nav-link:hover {
  background-color: var(--color-slate-100);
}

/* Language switcher */
.lang-switcher {
  display: flex;
  align-items: center;
  gap: var(--spacing-1);
  border: 1px solid var(--color-slate-200);
  border-radius: var(--radius-xl);
  padding: var(--spacing-1);
  background-color: white;
  box-shadow: var(--shadow-sm);
}

.lang-link {
  display: flex;
  align-items: center;
  gap: var(--spacing-2);
  padding: var(--spacing-2) var(--spacing-3);
  border-radius: var(--radius-xl);
  text-decoration: none;
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-slate-700);
  background-color: var(--color-slate-100);
  transition: all var(--transition-base);
}

.lang-link.active,
.lang-link:hover {
  background-color: white;
  outline: 2px solid var(--color-primary);
  outline-offset: -2px;
}

/* Mobile menu button */
.mobile-menu-btn {
  display: block;
  padding: var(--spacing-2);
  border: none;
  background: none;
  cursor: pointer;
  color: var(--color-slate-700);
  border-radius: var(--radius-lg);
  transition: background-color var(--transition-base);
}

.mobile-menu-btn:hover {
  background-color: var(--color-slate-100);
}

/* Hero section - Critical */
.hero {
  background: var(--gradient-hero);
  padding: var(--spacing-16) 0;
}

.hero .container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--spacing-4);
}

.hero-content {
  display: grid;
  gap: var(--spacing-12);
  align-items: center;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-2);
  padding: var(--spacing-2) var(--spacing-4);
  border-radius: 9999px;
  background-color: white;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--color-slate-200);
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-slate-700);
}

.hero-badge-dot {
  width: 0.75rem;
  height: 0.75rem;
  border-radius: 50%;
  background-color: var(--color-success);
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% {
    opacity: 1;
  }
  50% {
    opacity: 0.5;
  }
}

.hero h1 {
  font-size: var(--font-size-4xl);
  font-weight: 800;
  line-height: 1.1;
  color: var(--color-slate-900);
  margin-bottom: var(--spacing-6);
}

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

.hero p {
  font-size: var(--font-size-xl);
  color: var(--color-slate-600);
  line-height: 1.7;
  margin-bottom: var(--spacing-6);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-4) var(--spacing-8);
  border-radius: var(--radius-2xl);
  font-size: var(--font-size-lg);
  font-weight: 600;
  text-decoration: none;
  border: none;
  cursor: pointer;
  transition: all var(--transition-base);
}

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

.btn-primary:hover {
  box-shadow: var(--shadow-xl);
  transform: translateY(-2px);
}

.btn-secondary {
  background-color: white;
  color: var(--color-slate-800);
  border: 2px solid var(--color-slate-300);
}

.btn-secondary:hover {
  border-color: var(--color-primary-light);
  background-color: var(--color-slate-50);
}

/* Utility classes */
.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--spacing-4);
}

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

.sr-only:focus {
  position: static;
  width: auto;
  height: auto;
  padding: var(--spacing-2) var(--spacing-4);
  margin: 0;
  overflow: visible;
  clip: auto;
  white-space: normal;
}

/* Mobile first - show mobile menu button */
@media (min-width: 1024px) {
  .nav-links {
    display: flex;
  }
  
  .mobile-menu-btn {
    display: none;
  }
  
  .hero h1 {
    font-size: var(--font-size-6xl);
  }
  
  .hero-content {
    grid-template-columns: 1fr 1fr;
  }
}