/* ========================================
   CSS Custom Properties (Variables)
   ======================================== */
:root {
  /* Colors - Dark theme with accent */
  --color-bg: #0d1117;
  --color-bg-secondary: #161b22;
  --color-bg-tertiary: #21262d;
  --color-text: #c9d1d9;
  --color-text-muted: #8b949e;
  --color-text-heading: #f0f6fc;
  --color-accent: #58a6ff;
  --color-accent-hover: #79b8ff;
  --color-accent-muted: #1f6feb;
  --color-border: #30363d;
  --color-success: #3fb950;
  --color-warning: #d29922;
  --color-danger: #f85149;

  /* Typography */
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
  --font-mono: 'SF Mono', 'Fira Code', Consolas, monospace;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 2rem;
  --font-size-4xl: 2.5rem;

  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;

  /* Layout */
  --max-width: 1200px;
  --border-radius: 8px;
  --border-radius-lg: 12px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
}

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

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

body {
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

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

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

ul, ol {
  list-style-position: inside;
}

/* ========================================
   Typography
   ======================================== */
h1, h2, h3, h4, h5, h6 {
  color: var(--color-text-heading);
  line-height: 1.3;
  margin-bottom: var(--spacing-md);
}

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

p {
  margin-bottom: var(--spacing-md);
}

strong {
  color: var(--color-text-heading);
}

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

pre {
  background-color: var(--color-bg-tertiary);
  padding: var(--spacing-md);
  border-radius: var(--border-radius);
  overflow-x: auto;
  margin-bottom: var(--spacing-md);
}

pre code {
  background: none;
  padding: 0;
}

blockquote {
  border-left: 4px solid var(--color-accent);
  padding-left: var(--spacing-md);
  margin: var(--spacing-md) 0;
  color: var(--color-text-muted);
  font-style: italic;
}

/* ========================================
   Layout
   ======================================== */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

main {
  flex: 1;
  padding: var(--spacing-2xl) 0;
}

/* ========================================
   Header
   ======================================== */
.site-header {
  background-color: var(--color-bg-secondary);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-md);
}

.site-logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--color-text-heading);
}

.site-logo:hover {
  color: var(--color-accent);
}

.logo-icon {
  font-size: 1.5em;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--spacing-sm);
}

.hamburger {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--color-text);
  position: relative;
}

.hamburger::before,
.hamburger::after {
  content: '';
  position: absolute;
  width: 24px;
  height: 2px;
  background-color: var(--color-text);
  left: 0;
}

.hamburger::before { top: -7px; }
.hamburger::after { top: 7px; }

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

.nav-list a {
  color: var(--color-text);
  font-weight: 500;
  padding: var(--spacing-sm) 0;
  transition: color var(--transition-fast);
}

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

/* Mobile Navigation */
@media (max-width: 768px) {
  .nav-toggle {
    display: block;
  }

  .site-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--color-bg-secondary);
    border-bottom: 1px solid var(--color-border);
    display: none;
    padding: var(--spacing-md);
  }

  .site-nav.is-open {
    display: block;
  }

  .nav-list {
    flex-direction: column;
    gap: 0;
  }

  .nav-list li {
    border-bottom: 1px solid var(--color-border);
  }

  .nav-list li:last-child {
    border-bottom: none;
  }

  .nav-list a {
    display: block;
    padding: var(--spacing-md);
  }
}

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

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

.footer-social {
  display: flex;
  justify-content: center;
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
}

.social-link {
  color: var(--color-text-muted);
  transition: color var(--transition-fast), transform var(--transition-fast);
}

.social-link:hover {
  color: var(--color-accent);
  transform: translateY(-2px);
}

.footer-copyright {
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
  margin: 0;
}

/* ========================================
   Hero Section
   ======================================== */
.hero {
  text-align: center;
  padding: var(--spacing-3xl) 0;
  margin-bottom: var(--spacing-2xl);
  background: linear-gradient(180deg, var(--color-bg-secondary) 0%, var(--color-bg) 100%);
  border-radius: var(--border-radius-lg);
}

.hero h1 {
  font-size: clamp(var(--font-size-2xl), 5vw, var(--font-size-4xl));
  margin-bottom: var(--spacing-md);
}

.hero-subtitle {
  font-size: var(--font-size-lg);
  color: var(--color-text-muted);
  max-width: 600px;
  margin: 0 auto;
}

/* ========================================
   Posts Section
   ======================================== */
.section-title {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--spacing-xl);
  padding-bottom: var(--spacing-sm);
  border-bottom: 2px solid var(--color-border);
}

.posts-grid {
  display: grid;
  gap: var(--spacing-xl);
}

@media (min-width: 768px) {
  .posts-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .posts-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* ========================================
   Post Card
   ======================================== */
.post-card {
  background-color: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-lg);
  overflow: hidden;
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

.post-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.3);
}

.post-card-image {
  display: block;
  aspect-ratio: 16/9;
  overflow: hidden;
}

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

.post-card:hover .post-card-image img {
  transform: scale(1.05);
}

.post-card-content {
  padding: var(--spacing-lg);
}

.post-card-title {
  font-size: var(--font-size-xl);
  margin-bottom: var(--spacing-sm);
}

.post-card-title a {
  color: var(--color-text-heading);
}

.post-card-title a:hover {
  color: var(--color-accent);
}

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

.post-card-categories {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-xs);
}

.post-card-excerpt {
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
  margin-bottom: var(--spacing-md);
}

.read-more {
  font-size: var(--font-size-sm);
  font-weight: 600;
}

/* ========================================
   Category Badge
   ======================================== */
.category-badge {
  display: inline-block;
  background-color: var(--color-accent-muted);
  color: var(--color-text-heading);
  font-size: var(--font-size-sm);
  padding: 0.2em 0.6em;
  border-radius: 4px;
  transition: background-color var(--transition-fast);
}

.category-badge:hover {
  background-color: var(--color-accent);
  color: var(--color-bg);
}

/* ========================================
   Single Post
   ======================================== */
.post {
  max-width: 800px;
  margin: 0 auto;
}

.post-header {
  margin-bottom: var(--spacing-xl);
}

.post-title {
  font-size: clamp(var(--font-size-2xl), 4vw, var(--font-size-4xl));
}

.post-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--spacing-md);
  color: var(--color-text-muted);
}

.post-categories {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-xs);
}

.post-featured-image {
  margin-bottom: var(--spacing-xl);
  border-radius: var(--border-radius-lg);
  overflow: hidden;
}

.post-featured-image img {
  width: 100%;
}

.post-content {
  font-size: var(--font-size-lg);
  line-height: 1.8;
}

.post-content h2,
.post-content h3,
.post-content h4 {
  margin-top: var(--spacing-2xl);
}

.post-content img {
  border-radius: var(--border-radius);
  margin: var(--spacing-lg) 0;
}

.post-content ul,
.post-content ol {
  margin-bottom: var(--spacing-md);
  padding-left: var(--spacing-lg);
}

.post-content li {
  margin-bottom: var(--spacing-sm);
}

.post-footer {
  margin-top: var(--spacing-2xl);
  padding-top: var(--spacing-xl);
  border-top: 1px solid var(--color-border);
}

.back-link {
  font-weight: 600;
}

/* ========================================
   Page
   ======================================== */
.page {
  max-width: 800px;
  margin: 0 auto;
}

.page-content {
  font-size: var(--font-size-lg);
  line-height: 1.8;
}

.page-content h1 {
  margin-bottom: var(--spacing-xl);
}

.page-content h2,
.page-content h3 {
  margin-top: var(--spacing-2xl);
}

.page-content ul,
.page-content ol {
  margin-bottom: var(--spacing-md);
  padding-left: var(--spacing-lg);
}

.page-content li {
  margin-bottom: var(--spacing-sm);
}

/* ========================================
   Category Page
   ======================================== */
.category-page h1 {
  margin-bottom: var(--spacing-sm);
}

.category-description {
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-2xl);
  font-size: var(--font-size-lg);
}

/* ========================================
   Video Container (YouTube Embeds)
   ======================================== */
.video-container {
  position: relative;
  padding-bottom: 56.25%; /* 16:9 aspect ratio */
  height: 0;
  overflow: hidden;
  margin: var(--spacing-xl) 0;
  border-radius: var(--border-radius);
}

.video-container iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: none;
}

/* ========================================
   Download Button
   ======================================== */
.download-button {
  display: inline-block;
  background-color: var(--color-accent);
  color: var(--color-bg);
  font-weight: 600;
  padding: var(--spacing-md) var(--spacing-xl);
  border-radius: var(--border-radius);
  margin: var(--spacing-lg) 0;
  transition: background-color var(--transition-fast), transform var(--transition-fast);
}

.download-button:hover {
  background-color: var(--color-accent-hover);
  color: var(--color-bg);
  transform: translateY(-2px);
}

/* ========================================
   Button
   ======================================== */
.button {
  display: inline-block;
  background-color: var(--color-accent);
  color: var(--color-bg);
  font-weight: 600;
  padding: var(--spacing-md) var(--spacing-xl);
  border-radius: var(--border-radius);
  transition: background-color var(--transition-fast);
}

.button:hover {
  background-color: var(--color-accent-hover);
  color: var(--color-bg);
}

/* ========================================
   Error Page (404)
   ======================================== */
.error-page {
  text-align: center;
  padding: var(--spacing-3xl) 0;
}

.error-page h1 {
  font-size: 8rem;
  color: var(--color-accent);
  margin-bottom: 0;
}

.error-page h2 {
  margin-bottom: var(--spacing-lg);
}

.error-page p {
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-xl);
}

/* ========================================
   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;
}