/**
 * timeinrussia.com - Critical CSS
 * Performance-optimized, mobile-first, zero-CLS stylesheet
 */

/* ========================================
   CSS Variables (Dark/Light Mode Support)
   ======================================== */
:root {
  /* Light mode (default) */
  --bg-primary: #ffffff;
  --bg-secondary: #f8f9fa;
  --bg-tertiary: #e9ecef;
  --text-primary: #212529;
  --text-secondary: #6c757d;
  --text-tertiary: #adb5bd;
  --accent-primary: #0066cc;
  --accent-hover: #0052a3;
  --border-color: #dee2e6;
  --shadow: rgba(0, 0, 0, 0.1);
  --card-bg: #ffffff;

  /* Typography */
  --font-system: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SF Mono", Monaco, "Cascadia Code", "Roboto Mono", Consolas, monospace;

  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-xxl: 3rem;

  /* Layout */
  --max-width: 1200px;
  --header-height: 60px;
  --sidebar-width: 280px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-tertiary: #3a3a3a;
    --text-primary: #e9ecef;
    --text-secondary: #adb5bd;
    --text-tertiary: #6c757d;
    --accent-primary: #4da6ff;
    --accent-hover: #66b3ff;
    --border-color: #495057;
    --shadow: rgba(0, 0, 0, 0.3);
    --card-bg: #2d2d2d;
  }
}

[data-theme="dark"] {
  --bg-primary: #1a1a1a;
  --bg-secondary: #2d2d2d;
  --bg-tertiary: #3a3a3a;
  --text-primary: #e9ecef;
  --text-secondary: #adb5bd;
  --text-tertiary: #6c757d;
  --accent-primary: #4da6ff;
  --accent-hover: #66b3ff;
  --border-color: #495057;
  --shadow: rgba(0, 0, 0, 0.3);
  --card-bg: #2d2d2d;
}

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

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

body {
  font-family: var(--font-system);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
}

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

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

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

/* ========================================
   Header & Navigation
   ======================================== */
.site-header {
  background-color: var(--bg-primary);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 1000;
  height: var(--header-height);
  box-shadow: 0 2px 4px var(--shadow);
}

.header-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 100%;
}

.site-logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
}

.site-logo:hover {
  text-decoration: none;
}

.main-nav ul {
  display: flex;
  list-style: none;
  gap: var(--spacing-lg);
}

.main-nav a {
  color: var(--text-secondary);
  font-weight: 500;
  font-size: 0.9375rem;
}

.main-nav a:hover {
  color: var(--accent-primary);
  text-decoration: none;
}

/* Mobile Navigation */
.mobile-menu-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text-primary);
  font-size: 1.5rem;
  cursor: pointer;
  padding: var(--spacing-sm);
}

@media (max-width: 768px) {
  .mobile-menu-toggle {
    display: block;
  }

  .main-nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    transform: translateY(-100%);
    transition: transform 0.3s ease;
    box-shadow: 0 4px 6px var(--shadow);
  }

  .main-nav.active {
    transform: translateY(0);
  }

  .main-nav ul {
    flex-direction: column;
    padding: var(--spacing-lg);
    gap: var(--spacing-md);
  }
}

/* ========================================
   AdSense Slots (Zero CLS - Reserved Space)
   ======================================== */
.ad-slot {
  background-color: var(--bg-tertiary);
  border: 1px dashed var(--border-color);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: var(--spacing-xl) 0;
  min-height: 90px; /* Standard ad height */
  position: relative;
  overflow: hidden;
}

.ad-slot::before {
  content: 'Advertisement';
  color: var(--text-tertiary);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

/* Header Ad */
.ad-header {
  min-height: 90px;
  margin: var(--spacing-md) auto;
  max-width: 728px;
}

/* Sidebar Ad */
.ad-sidebar {
  min-height: 600px;
  width: 100%;
  margin: var(--spacing-lg) 0;
}

/* In-content Ad */
.ad-content {
  min-height: 280px;
  margin: var(--spacing-xxl) 0;
}

@media (max-width: 768px) {
  .ad-header {
    min-height: 50px;
    max-width: 320px;
  }

  .ad-sidebar {
    min-height: 250px;
  }

  .ad-content {
    min-height: 250px;
  }
}

/* ========================================
   Layout
   ======================================== */
.main-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--spacing-lg);
  min-height: calc(100vh - var(--header-height));
}

.content-wrapper {
  display: grid;
  grid-template-columns: 1fr var(--sidebar-width);
  gap: var(--spacing-xl);
  margin-top: var(--spacing-lg);
}

@media (max-width: 1024px) {
  .content-wrapper {
    grid-template-columns: 1fr;
  }
}

/* ========================================
   Hero Section (Digital Clock)
   ======================================== */
.hero-section {
  text-align: center;
  padding: var(--spacing-xxl) 0;
  background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-tertiary) 100%);
  border-radius: 12px;
  margin-bottom: var(--spacing-xl);
}

.hero-title {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

.hero-subtitle {
  font-size: 1.125rem;
  color: var(--text-secondary);
  margin-bottom: var(--spacing-xl);
}

.city-selector {
  margin-bottom: var(--spacing-xl);
}

.city-selector select {
  font-size: 1.125rem;
  padding: var(--spacing-md) var(--spacing-lg);
  border: 2px solid var(--border-color);
  border-radius: 8px;
  background-color: var(--card-bg);
  color: var(--text-primary);
  cursor: pointer;
  font-family: var(--font-system);
  transition: border-color 0.2s ease;
}

.city-selector select:focus {
  outline: none;
  border-color: var(--accent-primary);
}

.digital-clock {
  font-family: var(--font-mono);
  font-size: 4rem;
  font-weight: 700;
  color: var(--accent-primary);
  letter-spacing: 0.05em;
  margin: var(--spacing-lg) 0;
  text-shadow: 0 2px 10px var(--shadow);
}

.clock-date {
  font-size: 1.25rem;
  color: var(--text-secondary);
  margin-top: var(--spacing-md);
}

.timezone-info {
  font-size: 1rem;
  color: var(--text-tertiary);
  margin-top: var(--spacing-sm);
}

@media (max-width: 768px) {
  .hero-title {
    font-size: 1.75rem;
  }

  .digital-clock {
    font-size: 2.5rem;
  }

  .hero-section {
    padding: var(--spacing-xl) var(--spacing-md);
  }
}

/* ========================================
   Map Section (Reserved space - zero CLS)
   ======================================== */
.map-section {
  margin: var(--spacing-xxl) 0;
}

.section-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: var(--spacing-lg);
  color: var(--text-primary);
}

.map-container {
  width: 100%;
  height: 500px; /* Fixed height to prevent CLS */
  background-color: var(--bg-tertiary);
  border-radius: 12px;
  overflow: hidden;
  position: relative;
  border: 1px solid var(--border-color);
}

.map-placeholder {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: var(--text-tertiary);
  font-size: 1.125rem;
}

#map {
  width: 100%;
  height: 100%;
  z-index: 1;
}

@media (max-width: 768px) {
  .map-container {
    height: 400px;
  }
}

/* ========================================
   Content Section (SEO Article)
   ======================================== */
.content-section {
  margin: var(--spacing-xxl) 0;
}

.content-article {
  background-color: var(--card-bg);
  padding: var(--spacing-xl);
  border-radius: 12px;
  box-shadow: 0 2px 8px var(--shadow);
}

.content-article h2 {
  font-size: 1.75rem;
  font-weight: 700;
  margin-top: var(--spacing-xl);
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

.content-article h3 {
  font-size: 1.375rem;
  font-weight: 600;
  margin-top: var(--spacing-lg);
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

.content-article p {
  margin-bottom: var(--spacing-md);
  line-height: 1.8;
  color: var(--text-primary);
}

.content-article ul, .content-article ol {
  margin: var(--spacing-md) 0;
  padding-left: var(--spacing-xl);
}

.content-article li {
  margin-bottom: var(--spacing-sm);
  line-height: 1.8;
}

.faq-item {
  margin-bottom: var(--spacing-xl);
  padding-bottom: var(--spacing-lg);
  border-bottom: 1px solid var(--border-color);
}

.faq-item:last-child {
  border-bottom: none;
}

.faq-question {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  color: var(--accent-primary);
}

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

/* ========================================
   Sidebar
   ======================================== */
.sidebar {
  position: sticky;
  top: calc(var(--header-height) + var(--spacing-lg));
  height: fit-content;
}

.sidebar-widget {
  background-color: var(--card-bg);
  padding: var(--spacing-lg);
  border-radius: 12px;
  margin-bottom: var(--spacing-lg);
  box-shadow: 0 2px 8px var(--shadow);
}

.widget-title {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

.city-clock-list {
  list-style: none;
}

.city-clock-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-sm) 0;
  border-bottom: 1px solid var(--border-color);
}

.city-clock-item:last-child {
  border-bottom: none;
}

.city-name {
  font-weight: 500;
  color: var(--text-primary);
}

.city-time {
  font-family: var(--font-mono);
  font-weight: 600;
  color: var(--accent-primary);
  font-size: 0.9375rem;
}

.city-offset {
  font-size: 0.75rem;
  color: var(--text-tertiary);
  display: block;
}

/* Search Widget */
.search-widget {
  margin-bottom: var(--spacing-lg);
}

.search-input {
  width: 100%;
  padding: var(--spacing-md);
  border: 2px solid var(--border-color);
  border-radius: 8px;
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  font-family: var(--font-system);
  font-size: 1rem;
  transition: border-color 0.2s ease;
}

.search-input:focus {
  outline: none;
  border-color: var(--accent-primary);
}

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

/* ========================================
   Footer
   ======================================== */
.site-footer {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  margin-top: var(--spacing-xxl);
  padding: var(--spacing-xxl) 0;
}

.footer-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--spacing-xl);
  margin-bottom: var(--spacing-xl);
}

.footer-column h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

.footer-column ul {
  list-style: none;
}

.footer-column li {
  margin-bottom: var(--spacing-sm);
}

.footer-column a {
  color: var(--text-secondary);
  font-size: 0.9375rem;
}

.footer-bottom {
  text-align: center;
  padding-top: var(--spacing-lg);
  border-top: 1px solid var(--border-color);
  color: var(--text-secondary);
  font-size: 0.875rem;
}

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

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

.mt-lg {
  margin-top: var(--spacing-lg);
}

.mb-lg {
  margin-bottom: var(--spacing-lg);
}

/* ========================================
   Loading Spinner (for lazy-loaded elements)
   ======================================== */
.spinner {
  border: 3px solid var(--border-color);
  border-top: 3px solid var(--accent-primary);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  animation: spin 1s linear infinite;
  margin: var(--spacing-lg) auto;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

/* ========================================
   Time Zone Converter Specific Styles
   ======================================== */
.converter-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-lg);
  margin: var(--spacing-xl) 0;
}

.converter-zone {
  background-color: var(--card-bg);
  padding: var(--spacing-lg);
  border-radius: 12px;
  border: 2px solid var(--border-color);
  text-align: center;
  transition: border-color 0.2s ease;
}

.converter-zone:hover {
  border-color: var(--accent-primary);
}

.zone-label {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: var(--spacing-sm);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.zone-time-large {
  font-family: var(--font-mono);
  font-size: 2rem;
  font-weight: 700;
  color: var(--accent-primary);
  margin: var(--spacing-sm) 0;
}

/* ========================================
   Responsive Typography
   ======================================== */
@media (max-width: 768px) {
  html {
    font-size: 14px;
  }

  .section-title {
    font-size: 1.5rem;
  }

  .content-article h2 {
    font-size: 1.375rem;
  }

  .content-article h3 {
    font-size: 1.125rem;
  }
}

/* ========================================
   Print Styles
   ======================================== */
@media print {
  .site-header,
  .site-footer,
  .sidebar,
  .ad-slot,
  .map-container,
  .search-widget {
    display: none;
  }

  .content-wrapper {
    grid-template-columns: 1fr;
  }

  body {
    background-color: #ffffff;
    color: #000000;
  }
}

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

@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;
  }
}

/* Skip to main content link */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background-color: var(--accent-primary);
  color: #ffffff;
  padding: var(--spacing-sm) var(--spacing-md);
  text-decoration: none;
  z-index: 100;
}

.skip-link:focus {
  top: 0;
}