/* ============================================
   Successful Code Blog - Modern CSS Theme
   Dark Mode by Default
   ============================================ */

/* CSS Custom Properties - Dark Theme (Default) */
:root {
  /* Colors */
  --color-primary: #818cf8;
  --color-primary-dark: #6366f1;
  --color-primary-light: #a5b4fc;
  --color-secondary: #34d399;
  --color-accent: #a78bfa;
  
  /* Background - Dark Mode Default */
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --bg-card: #1e293b;
  
  /* Text - Dark Mode Default */
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-tertiary: #94a3b8;
  --text-muted: #64748b;
  
  /* Borders */
  --border-color: #334155;
  --border-hover: #475569;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -2px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -4px rgba(0, 0, 0, 0.3);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.5), 0 8px 10px -6px rgba(0, 0, 0, 0.4);
  --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.3);
  
  /* Gradients */
  --gradient-primary: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #a855f7 100%);
  --gradient-secondary: linear-gradient(135deg, #10b981 0%, #06b6d4 100%);
  --gradient-hero: linear-gradient(135deg, #0f172a 0%, #1e1b4b 50%, #0c4a6e 100%);
  --gradient-card: linear-gradient(145deg, rgba(30, 41, 59, 0.8) 0%, rgba(30, 41, 59, 0.4) 100%);
  
  /* Typography */
  --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
  --font-display: 'Plus Jakarta Sans', var(--font-sans);
  
  /* 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;
  --space-4xl: 6rem;
  
  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  --radius-full: 9999px;
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 200ms ease;
  --transition-slow: 300ms ease;
}

/* Light Theme */
[data-theme="light"] {
  --color-primary: #6366f1;
  --color-primary-dark: #4f46e5;
  --color-primary-light: #818cf8;
  
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-tertiary: #f1f5f9;
  --bg-card: #ffffff;
  
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-tertiary: #64748b;
  --text-muted: #94a3b8;
  
  --border-color: #e2e8f0;
  --border-hover: #cbd5e1;
  
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
  --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.15);
  
  --gradient-hero: linear-gradient(135deg, #f8fafc 0%, #e0e7ff 50%, #f0fdfa 100%);
  --gradient-card: linear-gradient(145deg, rgba(255, 255, 255, 0.9) 0%, rgba(248, 250, 252, 0.6) 100%);
}

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

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  min-height: 100vh;
  transition: background-color var(--transition-base), color var(--transition-base);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

/* ============================================
   Typography
   ============================================ */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.25;
  margin-bottom: var(--space-md);
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

h1 { font-size: clamp(2.25rem, 5vw, 3.75rem); font-weight: 800; }
h2 { font-size: clamp(1.75rem, 4vw, 2.75rem); }
h3 { font-size: clamp(1.375rem, 3vw, 1.875rem); }
h4 { font-size: 1.375rem; }
h5 { font-size: 1.125rem; }
h6 { font-size: 1rem; }

p {
  margin-bottom: var(--space-md);
  color: var(--text-secondary);
  font-size: 1.0625rem;
}

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

a:hover {
  color: var(--color-primary-light);
}

code, pre {
  font-family: var(--font-mono);
  background-color: var(--bg-tertiary);
  border-radius: var(--radius-sm);
}

code {
  padding: 0.2em 0.4em;
  font-size: 0.875em;
  color: var(--color-accent);
}

pre {
  padding: var(--space-lg);
  overflow-x: auto;
  margin-bottom: var(--space-lg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
}

pre code {
  padding: 0;
  background: transparent;
  color: var(--text-secondary);
}

/* ============================================
   Layout
   ============================================ */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.container-narrow {
  max-width: 800px;
}

/* ============================================
   Header & Navigation
   ============================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(15, 23, 42, 0.85);
  border-bottom: 1px solid var(--border-color);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

[data-theme="light"] .site-header {
  background-color: rgba(255, 255, 255, 0.85);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  text-decoration: none;
}

.logo-icon {
  flex-shrink: 0;
}

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

.header-right {
  display: flex;
  align-items: center;
  gap: var(--space-xl);
}

.nav-main {
  display: flex;
  align-items: center;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: var(--space-sm);
}

.nav-links a {
  font-weight: 500;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-lg);
  transition: all var(--transition-fast);
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--color-primary);
  background-color: rgba(99, 102, 241, 0.1);
}

/* Theme Toggle */
.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border: 1px solid var(--border-color);
  background-color: var(--bg-secondary);
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition-fast);
  color: var(--text-secondary);
}

.theme-toggle:hover {
  background-color: var(--bg-tertiary);
  color: var(--color-primary);
  border-color: var(--color-primary);
  box-shadow: var(--shadow-glow);
}

.theme-toggle .icon-sun {
  display: block;
}

.theme-toggle .icon-moon {
  display: none;
}

[data-theme="light"] .theme-toggle .icon-sun {
  display: none;
}

[data-theme="light"] .theme-toggle .icon-moon {
  display: block;
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  padding: 10px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  cursor: pointer;
}

.mobile-menu-toggle span {
  display: block;
  height: 2px;
  background-color: var(--text-primary);
  border-radius: 2px;
  transition: all var(--transition-fast);
}

/* ============================================
   Hero Section
   ============================================ */
.hero {
  background: var(--gradient-hero);
  padding: var(--space-4xl) 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-image: 
    radial-gradient(circle at 20% 80%, rgba(99, 102, 241, 0.15) 0%, transparent 50%),
    radial-gradient(circle at 80% 20%, rgba(16, 185, 129, 0.1) 0%, transparent 50%),
    radial-gradient(circle at 50% 50%, rgba(139, 92, 246, 0.1) 0%, transparent 60%);
  pointer-events: none;
}

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

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

.hero-description {
  font-size: 1.25rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto var(--space-xl);
  line-height: 1.8;
}

.hero-cta {
  display: flex;
  gap: var(--space-md);
  justify-content: center;
  flex-wrap: wrap;
}

/* ============================================
   Buttons
   ============================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: 0.75rem 1.5rem;
  font-size: 1rem;
  font-weight: 600;
  font-family: var(--font-sans);
  border-radius: var(--radius-lg);
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
}

.btn-primary {
  background: var(--gradient-primary);
  color: white;
  box-shadow: var(--shadow-md), 0 0 0 0 rgba(99, 102, 241, 0.4);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg), 0 0 20px rgba(99, 102, 241, 0.4);
  color: white;
}

.btn-secondary {
  background-color: var(--bg-card);
  color: var(--text-primary);
  border: 2px solid var(--border-color);
}

.btn-secondary:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background-color: rgba(99, 102, 241, 0.1);
}

/* ============================================
   Blog Cards
   ============================================ */
.posts-section {
  padding: var(--space-4xl) 0;
}

.section-header {
  text-align: center;
  margin-bottom: var(--space-3xl);
}

.section-header h2 {
  margin-bottom: var(--space-sm);
}

.section-header p {
  color: var(--text-tertiary);
  font-size: 1.125rem;
  max-width: 600px;
  margin: 0 auto;
}

.posts-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
  gap: var(--space-xl);
}

.post-card {
  background: var(--gradient-card);
  background-color: var(--bg-card);
  border-radius: var(--radius-2xl);
  border: 1px solid var(--border-color);
  overflow: hidden;
  transition: all var(--transition-base);
  display: flex;
  flex-direction: column;
}

.post-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-xl), var(--shadow-glow);
  border-color: rgba(99, 102, 241, 0.5);
}

.post-card-image {
  position: relative;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background: var(--gradient-primary);
}

.post-card-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-slow);
}

.post-card:hover .post-card-image img {
  transform: scale(1.08);
}

.post-card-category {
  position: absolute;
  top: var(--space-md);
  left: var(--space-md);
  padding: var(--space-xs) var(--space-md);
  background: var(--gradient-primary);
  color: white;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  border-radius: var(--radius-full);
  box-shadow: var(--shadow-md);
}

.post-card-content {
  padding: var(--space-xl);
  display: flex;
  flex-direction: column;
  flex-grow: 1;
}

.post-card-meta {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  margin-bottom: var(--space-md);
  font-size: 0.875rem;
  color: var(--text-muted);
}

.post-card-meta span {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.post-card h3 {
  font-size: 1.375rem;
  margin-bottom: var(--space-sm);
  line-height: 1.3;
}

.post-card h3 a {
  color: var(--text-primary);
  transition: color var(--transition-fast);
}

.post-card h3 a:hover {
  color: var(--color-primary);
}

.post-card-excerpt {
  color: var(--text-tertiary);
  flex-grow: 1;
  margin-bottom: var(--space-lg);
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
  line-height: 1.7;
}

.post-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--space-lg);
  border-top: 1px solid var(--border-color);
}

.post-author {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.post-author-avatar {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-full);
  background: var(--gradient-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 600;
  font-size: 0.875rem;
}

.post-author-name {
  font-weight: 500;
  font-size: 0.9375rem;
  color: var(--text-secondary);
}

.read-more {
  font-weight: 600;
  font-size: 0.9375rem;
  color: var(--color-primary);
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  transition: gap var(--transition-fast);
}

.read-more:hover {
  gap: var(--space-sm);
}

.read-more svg {
  transition: transform var(--transition-fast);
}

.read-more:hover svg {
  transform: translateX(4px);
}

/* ============================================
   Single Post
   ============================================ */
.post-header {
  padding: var(--space-4xl) 0 var(--space-2xl);
  background: var(--gradient-hero);
  text-align: center;
}

.post-header .container {
  max-width: 800px;
}

.post-category {
  display: inline-block;
  padding: var(--space-xs) var(--space-lg);
  background: var(--gradient-primary);
  color: white;
  font-size: 0.875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  border-radius: var(--radius-full);
  margin-bottom: var(--space-xl);
}

.post-title {
  margin-bottom: var(--space-xl);
}

.post-meta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xl);
  color: var(--text-tertiary);
  font-size: 1rem;
}

.post-meta-item {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.post-content {
  padding: var(--space-4xl) 0;
}

.post-content .container {
  max-width: 760px;
}

.post-body {
  font-size: 1.125rem;
  line-height: 1.85;
}

.post-body h2 {
  margin-top: var(--space-3xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--border-color);
}

.post-body h3 {
  margin-top: var(--space-2xl);
}

.post-body img {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-xl);
  margin: var(--space-2xl) 0;
  box-shadow: var(--shadow-lg);
}

.post-body blockquote {
  border-left: 4px solid var(--color-primary);
  padding: var(--space-lg) var(--space-xl);
  margin: var(--space-2xl) 0;
  background-color: var(--bg-secondary);
  border-radius: 0 var(--radius-lg) var(--radius-lg) 0;
  font-style: italic;
  color: var(--text-secondary);
}

.post-body ul, .post-body ol {
  margin-left: var(--space-xl);
  margin-bottom: var(--space-lg);
}

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

.post-body li::marker {
  color: var(--color-primary);
}

/* ============================================
   Footer
   ============================================ */
.site-footer {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: var(--space-4xl) 0 var(--space-2xl);
  margin-top: var(--space-4xl);
}

.footer-content {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: var(--space-3xl);
  margin-bottom: var(--space-3xl);
}

.footer-brand {
  max-width: 360px;
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  margin-bottom: var(--space-lg);
}

.footer-logo span {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
}

.footer-tagline {
  color: var(--text-tertiary);
  font-size: 0.9375rem;
  line-height: 1.7;
  margin: 0;
}

.footer-links h4 {
  font-family: var(--font-display);
  font-size: 0.8125rem;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--text-muted);
  margin-bottom: var(--space-lg);
  font-weight: 600;
}

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

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

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

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

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

.social-links a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  background-color: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.social-links a:hover {
  background-color: var(--color-primary);
  border-color: var(--color-primary);
  color: white;
  transform: translateY(-2px);
  box-shadow: var(--shadow-glow);
}

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

.footer-bottom p {
  color: var(--text-muted);
  font-size: 0.875rem;
  margin: 0;
}

.footer-bottom .powered-by a {
  color: var(--color-primary);
  font-weight: 500;
}

.footer-bottom .powered-by a:hover {
  text-decoration: underline;
}

/* ============================================
   Page Content (Standard Pages)
   ============================================ */
.page-content {
  padding: var(--space-4xl) 0;
}

.page-content .container {
  max-width: 800px;
}

.page-content h1 {
  margin-bottom: var(--space-2xl);
  text-align: center;
}

/* ============================================
   Blog Archive
   ============================================ */
.archive-header {
  padding: var(--space-3xl) 0;
  background: var(--gradient-hero);
  text-align: center;
}

.archive-header h1 {
  margin-bottom: var(--space-md);
}

.archive-header p {
  font-size: 1.125rem;
  max-width: 600px;
  margin: 0 auto;
}

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 1024px) {
  .footer-content {
    grid-template-columns: 1fr 1fr;
  }
  
  .footer-brand {
    grid-column: 1 / -1;
    max-width: 100%;
  }
}

@media (max-width: 768px) {
  .header-inner {
    height: 64px;
  }
  
  .nav-main {
    display: none;
  }
  
  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--bg-primary);
    flex-direction: column;
    padding: var(--space-lg);
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow-lg);
  }
  
  .nav-links.active {
    display: flex;
  }
  
  .mobile-menu-toggle {
    display: flex;
  }
  
  .hero {
    padding: var(--space-3xl) 0;
  }
  
  .posts-grid {
    grid-template-columns: 1fr;
  }
  
  .post-meta {
    flex-direction: column;
    gap: var(--space-sm);
  }
  
  .footer-content {
    grid-template-columns: 1fr;
    gap: var(--space-2xl);
  }
  
  .footer-brand {
    max-width: 100%;
  }
  
  .footer-bottom {
    flex-direction: column;
    text-align: center;
  }
  
  .social-links {
    justify-content: center;
  }
}

@media (max-width: 480px) {
  .posts-grid {
    grid-template-columns: 1fr;
  }
  
  .post-card-content {
    padding: var(--space-lg);
  }
}

/* ============================================
   Animations
   ============================================ */
@keyframes fadeInUp {
  from { 
    opacity: 0; 
    transform: translateY(24px); 
  }
  to { 
    opacity: 1; 
    transform: translateY(0); 
  }
}

.post-card {
  animation: fadeInUp 0.5s ease forwards;
  opacity: 0;
}

.post-card:nth-child(1) { animation-delay: 0.05s; }
.post-card:nth-child(2) { animation-delay: 0.1s; }
.post-card:nth-child(3) { animation-delay: 0.15s; }
.post-card:nth-child(4) { animation-delay: 0.2s; }
.post-card:nth-child(5) { animation-delay: 0.25s; }
.post-card:nth-child(6) { animation-delay: 0.3s; }

/* ============================================
   Utilities
   ============================================ */
.sr-only {
  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; }

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

/* Focus styles for accessibility */
*:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

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