/* ============================================
   Linux OS Insider - Terminal Green Design
   クラシックターミナル × モダンコードエディタ
   ============================================ */

/* ===== CSS Variables ===== */
:root {
  /* Terminal Green Color Palette */
  --terminal-black: #0d1117;
  --terminal-dark: #161b22;
  --terminal-mid: #21262d;
  --terminal-light: #30363d;
  --terminal-border: #3d444d;
  
  --neon-green: #00ff88;
  --neon-green-dim: #00cc6a;
  --neon-cyan: #00bcd4;
  --neon-blue: #58a6ff;
  
  --text-primary: #e6edf3;
  --text-secondary: #8b949e;
  --text-muted: #6e7681;
  --text-link: #00ff88;
  
  /* Fonts */
  --font-heading: 'JetBrains Mono', 'Fira Code', 'Noto Sans JP', monospace;
  --font-body: 'Noto Sans JP', 'Inter', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  
  /* 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;
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 400ms ease;
  
  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  
  /* Shadows & Glows */
  --glow-green: 0 0 20px rgba(0, 255, 136, 0.3);
  --glow-cyan: 0 0 20px rgba(0, 188, 212, 0.3);
  --shadow-card: 0 4px 6px rgba(0, 0, 0, 0.4);
}

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

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

body {
  font-family: var(--font-body);
  background: var(--terminal-black);
  color: var(--text-primary);
  line-height: 1.7;
  min-height: 100vh;
  overflow-x: hidden;
}

a {
  color: var(--neon-green);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--neon-cyan);
  text-shadow: 0 0 8px rgba(0, 255, 136, 0.5);
}

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

/* ===== Utilities ===== */
.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

/* ===== Scanline Effect (Subtle) ===== */
body::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 9999;
  background: repeating-linear-gradient(
    0deg,
    transparent,
    transparent 2px,
    rgba(0, 0, 0, 0.03) 2px,
    rgba(0, 0, 0, 0.03) 4px
  );
}

/* ===== Navigation ===== */
.main-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(13, 17, 23, 0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--terminal-border);
  padding: var(--space-md) 0;
}

.nav-container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  display: flex;
  flex-direction: column;
}

.logo-text {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--neon-green);
  letter-spacing: -0.02em;
}

.logo-text::before {
  content: '> ';
  color: var(--neon-cyan);
}

.logo-sub {
  font-size: 0.7rem;
  color: var(--text-muted);
  margin-top: 2px;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  list-style: none;
  flex-wrap: wrap;
}

.nav-item a {
  display: block;
  padding: var(--space-sm) var(--space-md);
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-secondary);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.nav-item a:hover,
.nav-item a.active {
  color: var(--neon-green);
  background: rgba(0, 255, 136, 0.1);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-sm);
}

.nav-toggle span {
  width: 24px;
  height: 2px;
  background: var(--neon-green);
  transition: all var(--transition-fast);
}

/* ===== Hero Section ===== */
.hero {
  position: relative;
  min-height: 80vh;
  display: flex;
  align-items: center;
  margin-top: 60px;
  overflow: hidden;
}

.hero-background {
  position: absolute;
  inset: 0;
  z-index: 0;
}

.hero-background img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: none;
}

.hero-background::after {
  content: '';
  position: absolute;
  inset: 0;
  background: 
    linear-gradient(135deg, rgba(13, 17, 23, 0.9) 0%, rgba(13, 17, 23, 0.7) 50%, rgba(13, 17, 23, 0.85) 100%),
    radial-gradient(ellipse at 20% 50%, rgba(0, 255, 136, 0.1) 0%, transparent 50%);
}

.hero-content {
  position: relative;
  z-index: 1;
  width: 100%;
  padding: var(--space-3xl) 0;
}

.hero-text {
  max-width: 800px;
}

.hero-text h1 {
  font-family: var(--font-heading);
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 700;
  line-height: 1.2;
  color: #ffffff;
  margin-bottom: var(--space-lg);
  text-shadow: 
    2px 2px 0 #000,
    -2px 2px 0 #000,
    2px -2px 0 #000,
    -2px -2px 0 #000,
    0 4px 8px rgba(0,0,0,0.5);
}

.hero-text h1::before {
  content: '$ ';
  color: var(--neon-green);
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-xl);
  line-height: 1.6;
}

.hero-keywords {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

.keyword-tag {
  display: inline-block;
  padding: var(--space-sm) var(--space-md);
  background: rgba(0, 255, 136, 0.1);
  border: 1px solid rgba(0, 255, 136, 0.3);
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  font-size: 0.875rem;
  color: var(--neon-green);
}

/* ===== Main Layout ===== */
.main-container {
  padding: var(--space-3xl) 0;
}

.content-wrapper {
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: var(--space-2xl);
}

/* ===== Main Content ===== */
.main-content {
  min-width: 0;
}

.main-content h2 {
  font-family: var(--font-heading);
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-sm);
  border-bottom: 2px solid var(--neon-green);
}

.main-content h2::before {
  content: '## ';
  color: var(--neon-green);
  font-weight: 400;
}

.main-content h3 {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--neon-cyan);
  margin: var(--space-xl) 0 var(--space-md);
}

.main-content h3::before {
  content: '### ';
  color: var(--text-muted);
}

.main-content p {
  color: var(--text-secondary);
  margin-bottom: var(--space-md);
  line-height: 1.8;
}

.overview {
  background: var(--terminal-dark);
  border: 1px solid var(--terminal-border);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  margin-bottom: var(--space-2xl);
}

/* ===== CTA Section ===== */
.cta-section {
  margin-top: var(--space-2xl);
}

.cta-section h2 {
  text-align: center;
}

.cta-section > p {
  text-align: center;
  max-width: 600px;
  margin: 0 auto var(--space-xl);
}

.cta-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
}

.cta-card {
  display: block;
  background: var(--terminal-dark);
  border: 1px solid var(--terminal-border);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.cta-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--neon-green), var(--neon-cyan));
  opacity: 0;
  transition: opacity var(--transition-base);
}

.cta-card:hover {
  border-color: var(--neon-green);
  transform: translateY(-4px);
  box-shadow: var(--glow-green);
}

.cta-card:hover::before {
  opacity: 1;
}

.cta-card h3 {
  font-family: var(--font-heading);
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--neon-green);
  margin-bottom: var(--space-sm);
}

.cta-card h3::before {
  content: '→ ';
  color: var(--text-muted);
}

.cta-card p {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin: 0;
}

/* ===== Sidebar ===== */
.sidebar {
  display: flex;
  flex-direction: column;
  gap: var(--space-xl);
}

.sidebar-section {
  background: var(--terminal-dark);
  border: 1px solid var(--terminal-border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
}

.sidebar-section h3 {
  font-family: var(--font-heading);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--neon-green);
  margin-bottom: var(--space-md);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--terminal-border);
}

.sidebar-section h3::before {
  content: '# ';
  color: var(--text-muted);
}

.toc {
  list-style: none;
}

.toc li {
  margin-bottom: var(--space-sm);
}

.toc a {
  display: block;
  padding: var(--space-xs) var(--space-sm);
  font-size: 0.875rem;
  color: var(--text-secondary);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.toc a::before {
  content: '├─ ';
  color: var(--terminal-border);
}

.toc li:last-child a::before {
  content: '└─ ';
}

.toc a:hover {
  color: var(--neon-green);
  background: rgba(0, 255, 136, 0.05);
}

.ad-space {
  background: var(--terminal-mid);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  text-align: center;
}

.ad-space p {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin: var(--space-xs) 0;
}

.related-sites {
  list-style: none;
}

.related-sites li {
  margin-bottom: var(--space-sm);
}

.related-sites a {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.related-sites a:hover {
  color: var(--neon-green);
}

/* ===== News Section ===== */
.news-section {
  margin-top: var(--space-2xl);
  padding: var(--space-2xl);
  background: var(--terminal-dark);
  border: 1px solid var(--terminal-border);
  border-radius: var(--radius-lg);
}

.news-section h2 {
  text-align: center;
  margin-bottom: var(--space-xl);
}

.news-list {
  list-style: none;
}

.news-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-lg);
  padding: var(--space-md) 0;
  border-bottom: 1px solid var(--terminal-border);
}

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

.news-item time {
  flex-shrink: 0;
  font-family: var(--font-mono);
  font-size: 0.875rem;
  color: var(--neon-cyan);
}

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

.news-item a:hover {
  color: var(--neon-green);
}

/* ===== Footer ===== */
footer {
  background: var(--terminal-dark);
  border-top: 1px solid var(--terminal-border);
  padding: var(--space-3xl) 0 var(--space-xl);
  margin-top: var(--space-3xl);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr repeat(4, 1fr);
  gap: var(--space-2xl);
  margin-bottom: var(--space-2xl);
}

.footer-brand .logo-text {
  font-size: 1.5rem;
  margin-bottom: var(--space-md);
  display: block;
}

.footer-description {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.7;
  margin-bottom: var(--space-lg);
}

.footer-social {
  display: flex;
  gap: var(--space-md);
}

.social-link {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--terminal-mid);
  border: 1px solid var(--terminal-border);
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.social-link:hover {
  border-color: var(--neon-green);
  color: var(--neon-green);
  box-shadow: var(--glow-green);
}

.social-link svg {
  width: 18px;
  height: 18px;
}

.footer-links h4 {
  font-family: var(--font-heading);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--neon-green);
  margin-bottom: var(--space-md);
}

.footer-links h4::before {
  content: '$ ';
  color: var(--text-muted);
}

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

.footer-links li {
  margin-bottom: var(--space-sm);
}

.footer-links a {
  font-size: 0.875rem;
  color: var(--text-muted);
}

.footer-links a:hover {
  color: var(--neon-green);
}

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: var(--space-xl);
  border-top: 1px solid var(--terminal-border);
}

.footer-copyright {
  font-size: 0.8125rem;
  color: var(--text-muted);
}

.footer-legal {
  display: flex;
  gap: var(--space-lg);
}

.footer-legal a {
  font-size: 0.8125rem;
  color: var(--text-muted);
}

/* ===== Mobile Menu Overlay ===== */
.mobile-menu-overlay {
  position: fixed;
  inset: 0;
  z-index: 2000;
  background: rgba(13, 17, 23, 0.98);
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-base);
}

.mobile-menu-overlay.active {
  opacity: 1;
  visibility: visible;
}

.mobile-menu {
  position: absolute;
  top: 0;
  right: 0;
  width: 100%;
  max-width: 320px;
  height: 100%;
  background: var(--terminal-dark);
  border-left: 1px solid var(--neon-green);
  padding: var(--space-lg);
  transform: translateX(100%);
  transition: transform var(--transition-base);
  overflow-y: auto;
}

.mobile-menu-overlay.active .mobile-menu {
  transform: translateX(0);
}

.mobile-menu-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-xl);
  padding-bottom: var(--space-md);
  border-bottom: 1px solid var(--terminal-border);
}

.mobile-menu-close {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: none;
  border: 1px solid var(--terminal-border);
  border-radius: var(--radius-md);
  font-size: 1.5rem;
  color: var(--neon-green);
  cursor: pointer;
}

.mobile-nav-link {
  display: block;
  padding: var(--space-sm) 0;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--terminal-border);
}

.mobile-nav-link:hover {
  color: var(--neon-green);
}

/* ===== Page Hero (Subpages) ===== */
.page-hero {
  position: relative;
  padding: calc(80px + var(--space-3xl)) 0 var(--space-2xl);
  background: linear-gradient(135deg, var(--terminal-dark) 0%, var(--terminal-black) 100%);
  border-bottom: 1px solid var(--terminal-border);
}

.page-hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at 30% 50%, rgba(0, 255, 136, 0.05) 0%, transparent 50%);
}

.page-hero .container {
  position: relative;
  z-index: 1;
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--text-muted);
  margin-bottom: var(--space-lg);
}

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

.breadcrumb span {
  color: var(--neon-green);
}

.page-title {
  font-family: var(--font-heading);
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--space-md);
}

.page-title::before {
  content: '$ cat ';
  color: var(--neon-green);
  font-weight: 400;
}

.page-description {
  font-size: 1.125rem;
  color: var(--text-secondary);
  max-width: 700px;
}

/* ===== Article Content ===== */
.article-content {
  background: var(--terminal-dark);
  border: 1px solid var(--terminal-border);
  border-radius: var(--radius-lg);
  padding: var(--space-2xl);
}

.article-content h2 {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: var(--space-2xl) 0 var(--space-md);
  padding-bottom: var(--space-sm);
  border-bottom: 2px solid var(--neon-green);
}

.article-content h2:first-child {
  margin-top: 0;
}

.article-content h2::before {
  content: '## ';
  color: var(--neon-green);
}

.article-content h3 {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--neon-cyan);
  margin: var(--space-xl) 0 var(--space-md);
}

.article-content p {
  color: var(--text-secondary);
  margin-bottom: var(--space-md);
}

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

.article-content li {
  margin-bottom: var(--space-sm);
}

.article-content blockquote {
  background: var(--terminal-mid);
  border-left: 4px solid var(--neon-green);
  padding: var(--space-lg);
  margin: var(--space-xl) 0;
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

.article-content blockquote p {
  color: var(--text-primary);
  font-style: italic;
  margin: 0;
}

.article-content code {
  font-family: var(--font-mono);
  background: var(--terminal-mid);
  padding: 0.2em 0.4em;
  border-radius: var(--radius-sm);
  font-size: 0.9em;
  color: var(--neon-green);
}

.article-content pre {
  background: var(--terminal-black);
  border: 1px solid var(--terminal-border);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  overflow-x: auto;
  margin: var(--space-xl) 0;
}

.article-content pre code {
  background: none;
  padding: 0;
}

/* ===== Responsive ===== */
@media (max-width: 1024px) {
  .content-wrapper {
    grid-template-columns: 1fr;
  }
  
  .sidebar {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
  }
  
  .cta-grid {
    grid-template-columns: 1fr;
  }
  
  .footer-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  
  .footer-brand {
    grid-column: 1 / -1;
  }
}

@media (max-width: 768px) {
  .nav-menu {
    display: none;
  }
  
  .nav-toggle {
    display: flex;
  }
  
  .hero {
    min-height: 70vh;
  }
  
  .hero-text h1 {
    font-size: 1.75rem;
  }
  
  .hero-subtitle {
    font-size: 1rem;
  }
  
  .sidebar {
    grid-template-columns: 1fr;
  }
  
  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .footer-bottom {
    flex-direction: column;
    gap: var(--space-md);
    text-align: center;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--space-md);
  }
  
  .footer-grid {
    grid-template-columns: 1fr;
  }
  
  .hero-keywords {
    flex-direction: column;
  }
  
  .keyword-tag {
    text-align: center;
  }
}