/* ============================================
   VARIABLES
   ============================================ */
:root {
  /* Colors - Deep Navy & Electric Accents */
  --color-bg-primary: #0a192f;
  --color-bg-secondary: #112240;
  --color-bg-tertiary: #1d2d50;
  --color-text-primary: #f8fafc;
  --color-text-secondary: #94a3b8;
  --color-text-muted: #64748b;
  --color-accent-primary: #00d4ff;
  --color-accent-secondary: #38bdf8;
  --color-accent-hover: #7dd3fc;
  --color-success: #10b981;
  --color-warning: #f59e0b;
  --color-danger: #ef4444;
  --color-border: rgba(148, 163, 184, 0.15);
  
  /* Typography - Cyrillic/Ukrainian Support */
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'Noto Sans', sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol', 'Noto Color Emoji';
  --font-mono: 'SF Mono', 'Fira Code', 'Fira Mono', 'Roboto Mono', monospace;
  
  /* Fluid Type Scale */
  --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
  --text-sm: clamp(0.875rem, 0.8rem + 0.25vw, 1rem);
  --text-base: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);
  --text-lg: clamp(1.125rem, 1rem + 0.5vw, 1.25rem);
  --text-xl: clamp(1.25rem, 1.1rem + 0.75vw, 1.5rem);
  --text-2xl: clamp(1.5rem, 1.3rem + 1vw, 2rem);
  --text-3xl: clamp(1.875rem, 1.6rem + 1.25vw, 2.5rem);
  --text-4xl: clamp(2.25rem, 1.9rem + 1.75vw, 3rem);
  --text-5xl: clamp(3rem, 2.5rem + 2.5vw, 4rem);
  
  /* Line Heights */
  --leading-tight: 1.2;
  --leading-snug: 1.375;
  --leading-normal: 1.6;
  --leading-relaxed: 1.75;
  
  /* Spacing Scale (0-96px) */
  --space-0: 0;
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;
  
  /* Radius */
  --radius-sm: 0.25rem;
  --radius-md: 0.375rem;
  --radius-lg: 0.5rem;
  --radius-xl: 0.75rem;
  --radius-2xl: 1rem;
  --radius-full: 9999px;
  
  /* Shadows - Sophisticated Corporate */
  --shadow-sm: 0 1px 2px 0 rgba(2, 6, 23, 0.5);
  --shadow-md: 0 4px 6px -1px rgba(2, 6, 23, 0.5), 0 2px 4px -2px rgba(2, 6, 23, 0.4);
  --shadow-lg: 0 10px 15px -3px rgba(2, 6, 23, 0.5), 0 4px 6px -4px rgba(2, 6, 23, 0.4);
  --shadow-xl: 0 20px 25px -5px rgba(2, 6, 23, 0.5), 0 8px 10px -6px rgba(2, 6, 23, 0.4);
  --shadow-glow: 0 0 20px rgba(0, 212, 255, 0.15);
  
  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
  
  /* Layout */
  --container-max: 1280px;
  --container-padding: clamp(1rem, 5vw, 3rem);
}

/* ============================================
   RESET & NORMALIZE
   ============================================ */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

body {
  min-height: 100vh;
  line-height: var(--leading-normal);
  font-family: var(--font-sans);
  font-size: var(--text-base);
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
}

img,
picture,
video,
canvas,
svg {
  display: block;
  max-width: 100%;
  height: auto;
}

input,
button,
textarea,
select {
  font: inherit;
  color: inherit;
}

p,
h1,
h2,
h3,
h4,
h5,
h6 {
  overflow-wrap: break-word;
}

ul,
ol {
  list-style: none;
}

/* ============================================
   BASE STYLES
   ============================================ */
body {
  background-color: var(--color-bg-primary);
  color: var(--color-text-primary);
  font-family: var(--font-sans);
  line-height: var(--leading-normal);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* Headings */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: var(--leading-tight);
  letter-spacing: -0.02em;
  color: var(--color-text-primary);
  margin-bottom: var(--space-4);
}

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

/* Paragraphs */
p {
  margin-bottom: var(--space-4);
  color: var(--color-text-secondary);
  }

/* Links */
a {
  color: var(--color-accent-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-accent-hover);
}

/* ============================================
   UTILITIES
   ============================================ */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--container-padding);
}

.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;
}

/* Flex Helpers */
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }

/* Grid Helpers */
.grid { display: grid; }

/* ============================================
   COMPONENTS
   ============================================ */

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  font-size: var(--text-sm);
  font-weight: 500;
  line-height: 1;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all var(--transition-base);
  white-space: nowrap;
  letter-spacing: 0.01em;
}

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

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn--primary {
  background-color: var(--color-accent-primary);
  color: var(--color-bg-primary)!important;
  box-shadow: var(--shadow-glow);
}

.btn--primary:hover:not(:disabled) {
  background-color: var(--color-accent-hover);
  transform: translateY(-1px);
  box-shadow: 0 0 30px rgba(0, 212, 255, 0.25);
}

.btn--secondary {
  background-color: transparent;
  border-color: var(--color-accent-primary);
  color: var(--color-accent-primary);
}

.btn--secondary:hover:not(:disabled) {
  background-color: rgba(0, 212, 255, 0.1);
  color: var(--color-accent-hover);
}

.btn--ghost {
  background-color: transparent;
  color: var(--color-text-secondary);
}

.btn--ghost:hover:not(:disabled) {
  background-color: rgba(148, 163, 184, 0.1);
  color: var(--color-text-primary);
}

/* Inputs */
.input {
  width: 100%;
  padding: var(--space-3) var(--space-4);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--color-text-primary);
  background-color: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  transition: all var(--transition-base);
}

.input::placeholder {
  color: var(--color-text-muted);
}

.input:hover {
  border-color: var(--color-text-muted);
}

.input:focus {
  outline: none;
  border-color: var(--color-accent-primary);
  box-shadow: 0 0 0 3px rgba(0, 212, 255, 0.1);
}

.input:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* Cards */
.card {
  background-color: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  box-shadow: var(--shadow-md);
  transition: transform var(--transition-base), box-shadow var(--transition-base);
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg), var(--shadow-glow);
  border-color: rgba(148, 163, 184, 0.25);
}

/* ============================================
   ACCESSIBILITY
   ============================================ */
:focus-visible {
  outline: 2px solid var(--color-accent-primary);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  .btn,
  .card,
  .input,
  a {
    transition: none;
  }
  
  .card:hover,
  .btn:hover {
    transform: none;
  }
}

/* High Contrast Mode Support */
@media (prefers-contrast: high) {
  :root {
    --color-border: rgba(148, 163, 184, 0.5);
  }
  
  .card {
    border-width: 2px;
  }
}