/* ============================================
   CFO54.ru - Main Styles
   Управленческий учёт: от теории к практике
   ============================================ */

/* ============================================
   CSS Custom Properties (Design System)
   ============================================ */

:root {
  /* Primary Colors - профессиональный синий */
  --primary-color: #2563eb;
  --primary-dark: #1e40af;
  --primary-light: #60a5fa;
  
  /* Secondary Colors - акцентный зелёный (рост, прибыль) */
  --secondary-color: #10b981;
  --secondary-dark: #059669;
  --secondary-light: #34d399;
  
  /* Neutral Colors */
  --background: #ffffff;
  --surface: #f8f9fa;
  --surface-dark: #e9ecef;
  --text-primary: #1a1a1a;
  --text-secondary: #6c757d;
  --text-muted: #adb5bd;
  --border: #dee2e6;
  
  /* Semantic Colors */
  --success: #10b981;
  --warning: #f59e0b;
  --error: #ef4444;
  --info: #3b82f6;
  
  /* Font Families */
  --font-heading: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'Fira Code', 'Courier New', monospace;
  
  /* Font Sizes */
  --text-xs: 0.75rem;    /* 12px */
  --text-sm: 0.875rem;   /* 14px */
  --text-base: 1rem;     /* 16px */
  --text-lg: 1.125rem;   /* 18px */
  --text-xl: 1.25rem;    /* 20px */
  --text-2xl: 1.5rem;    /* 24px */
  --text-3xl: 2rem;      /* 32px */
  --text-4xl: 2.5rem;    /* 40px */
  --text-5xl: 3rem;      /* 48px */
  
  /* Line Heights */
  --leading-tight: 1.25;
  --leading-normal: 1.5;
  --leading-relaxed: 1.75;
  
  /* Font Weights */
  --font-normal: 400;
  --font-medium: 500;
  --font-semibold: 600;
  --font-bold: 700;
  
  /* Spacing System */
  --space-xs: 0.25rem;   /* 4px */
  --space-sm: 0.5rem;    /* 8px */
  --space-md: 1rem;      /* 16px */
  --space-lg: 1.5rem;    /* 24px */
  --space-xl: 2rem;      /* 32px */
  --space-2xl: 3rem;     /* 48px */
  --space-3xl: 4rem;     /* 64px */
  --space-4xl: 6rem;     /* 96px */
  
  /* Breakpoints (for reference in media queries) */
  --breakpoint-mobile: 768px;
  --breakpoint-tablet: 1024px;
  --breakpoint-desktop: 1200px;
}

/* ============================================
   Reset & Base Styles
   ============================================ */

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--font-normal);
  line-height: var(--leading-relaxed);
  color: var(--text-primary);
  background-color: var(--background);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ============================================
   Typography
   ============================================ */

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: var(--font-bold);
  line-height: var(--leading-tight);
  color: var(--text-primary);
  margin-bottom: var(--space-lg);
}

h1 {
  font-size: var(--text-4xl);
  font-weight: var(--font-bold);
  letter-spacing: -0.02em;
}

h2 {
  font-size: var(--text-3xl);
  font-weight: var(--font-semibold);
}

h3 {
  font-size: var(--text-2xl);
  font-weight: var(--font-semibold);
  line-height: var(--leading-normal);
}

h4 {
  font-size: var(--text-xl);
  font-weight: var(--font-semibold);
}

h5 {
  font-size: var(--text-lg);
  font-weight: var(--font-medium);
}

h6 {
  font-size: var(--text-base);
  font-weight: var(--font-medium);
}

p {
  margin-bottom: var(--space-md);
  line-height: var(--leading-relaxed);
}

a {
  color: var(--primary-color);
  text-decoration: none;
  transition: all 0.2s ease;
}

a:hover {
  color: var(--primary-dark);
  text-decoration: underline;
}

a:focus {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
  border-radius: 2px;
}

a:focus:not(:focus-visible) {
  outline: none;
}

a:focus-visible {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
  border-radius: 2px;
}

strong, b {
  font-weight: var(--font-semibold);
}

em, i {
  font-style: italic;
}

code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background-color: var(--surface);
  padding: 0.2em 0.4em;
  border-radius: 4px;
}

/* ============================================
   Layout
   ============================================ */

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

section {
  padding: var(--space-3xl) 0;
}

/* ============================================
   Lists
   ============================================ */

ul, ol {
  margin-bottom: var(--space-md);
  padding-left: var(--space-xl);
}

li {
  margin-bottom: var(--space-sm);
  line-height: var(--leading-relaxed);
}

/* ============================================
   Images
   ============================================ */

img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* ============================================
   Utility Classes
   ============================================ */

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

.text-left {
  text-align: left;
}

.text-right {
  text-align: right;
}

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

.text-secondary {
  color: var(--text-secondary);
}

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

.bg-surface {
  background-color: var(--surface);
}

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

.mt-sm { margin-top: var(--space-sm); }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mt-xl { margin-top: var(--space-xl); }

.mb-sm { margin-bottom: var(--space-sm); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }
.mb-xl { margin-bottom: var(--space-xl); }

.pt-sm { padding-top: var(--space-sm); }
.pt-md { padding-top: var(--space-md); }
.pt-lg { padding-top: var(--space-lg); }
.pt-xl { padding-top: var(--space-xl); }

.pb-sm { padding-bottom: var(--space-sm); }
.pb-md { padding-bottom: var(--space-md); }
.pb-lg { padding-bottom: var(--space-lg); }
.pb-xl { padding-bottom: var(--space-xl); }

/* ============================================
   Animations
   ============================================ */

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

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.7; }
}

.animate-fade-in-up {
  animation: fadeInUp 0.6s ease-out;
}

.animate-fade-in {
  animation: fadeIn 0.4s ease-out;
}

/* Scroll-triggered animations */
.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: all 0.6s ease-out;
}

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

/* ============================================
   Accessibility - Focus Indicators
   ============================================ */

button:focus,
input:focus,
textarea:focus,
select:focus {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
  border-radius: 4px;
}

button:focus:not(:focus-visible),
input:focus:not(:focus-visible),
textarea:focus:not(:focus-visible),
select:focus:not(:focus-visible) {
  outline: none;
}

button:focus-visible,
input:focus-visible,
textarea:focus-visible,
select:focus-visible {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
}

/* Skip to main content link */
.skip-to-main {
  position: absolute;
  top: -100px;
  left: 0;
  background: var(--primary-color);
  color: white;
  padding: var(--space-md) var(--space-lg);
  text-decoration: none;
  z-index: 9999;
  border-radius: 0 0 4px 0;
  font-weight: var(--font-semibold);
}

.skip-to-main:focus {
  top: 0;
  outline: 2px solid white;
  outline-offset: -4px;
}

/* ============================================
   Accessibility - Screen Reader Only
   ============================================ */

.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-focusable:focus,
.sr-only-focusable:active {
  position: static;
  width: auto;
  height: auto;
  overflow: visible;
  clip: auto;
  white-space: normal;
}

/* ============================================
   Accessibility - Reduced Motion
   ============================================ */

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  
  .reveal {
    opacity: 1;
    transform: none;
  }
}