/* ========================================
   CYBER TECH BLOG - Design System
   现代极简主义 + 技术感 + 双主题支持
   ======================================== */

/* ========================================
   Light Theme (default)
   ======================================== */

:root {
  /* Colors - Light Theme */
  --color-bg-primary: #fafafa;
  --color-bg-secondary: #f4f4f5;
  --color-bg-tertiary: #e4e4e7;
  --color-bg-card: #ffffff;
  --color-bg-hover: #f0f0f3;
  
  --color-text-primary: #18181b;
  --color-text-secondary: #52525b;
  --color-text-muted: #a1a1aa;
  
  --color-brand: #059669;
  --color-brand-dim: #047857;
  --color-brand-glow: rgba(5, 150, 105, 0.1);
  --color-brand-subtle: rgba(5, 150, 105, 0.05);
  
  --color-accent-blue: #3b82f6;
  --color-accent-purple: #a855f7;
  --color-accent-orange: #f97316;
  --color-accent-pink: #ec4899;
  
  --color-border: rgba(0, 0, 0, 0.08);
  --color-border-hover: rgba(0, 0, 0, 0.12);
  --color-border-brand: rgba(5, 150, 105, 0.25);

  --header-bg: rgba(250, 250, 250, 0.8);
  
  /* Typography */
  --font-display: 'Space Grotesk', -apple-system, sans-serif;
  --font-body: 'Space Grotesk', -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  
  /* Spacing */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  --space-3xl: 64px;
  --space-4xl: 96px;
  
  /* Radius */
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;
  
  /* Shadows */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.1);
  --shadow-glow: 0 0 20px rgba(5, 150, 105, 0.15);
  
  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-base: 0.25s ease;
  --transition-slow: 0.4s ease;
}

/* ========================================
   Dark Theme
   ======================================== */

[data-theme="dark"] {
  --color-bg-primary: #0a0a0f;
  --color-bg-secondary: #12121a;
  --color-bg-tertiary: #1a1a24;
  --color-bg-card: #16161f;
  --color-bg-hover: #1e1e2a;
  
  --color-text-primary: #e4e4e7;
  --color-text-secondary: #a1a1aa;
  --color-text-muted: #71717a;
  
  --color-brand: #00ff88;
  --color-brand-dim: #00cc6a;
  --color-brand-glow: rgba(0, 255, 136, 0.15);
  --color-brand-subtle: rgba(0, 255, 136, 0.05);
  
  --color-border: rgba(255, 255, 255, 0.08);
  --color-border-hover: rgba(255, 255, 255, 0.15);
  --color-border-brand: rgba(0, 255, 136, 0.3);

  --header-bg: rgba(10, 10, 15, 0.8);
  
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 20px rgba(0, 255, 136, 0.2);
}

/* ========================================
   Base Styles
   ======================================== */

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

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

body {
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.7;
  color: var(--color-text-primary);
  background: var(--color-bg-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  transition: background var(--transition-base), color var(--transition-base);
}

body::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: 
    radial-gradient(circle at 20% 20%, var(--color-brand-glow) 0%, transparent 50%),
    radial-gradient(circle at 80% 80%, rgba(59, 130, 246, 0.03) 0%, transparent 50%);
  pointer-events: none;
  z-index: -1;
}

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

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

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

.container-narrow {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

/* ========================================
   Header
   ======================================== */

.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--header-bg);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-md) 0;
  transition: background var(--transition-base), border-color var(--transition-base);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-lg);
}

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

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

.logo {
  font-family: var(--font-mono);
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--color-text-primary);
  text-decoration: none;
  letter-spacing: -0.5px;
  position: relative;
  padding-left: var(--space-md);
}

.logo::before {
  content: '>';
  position: absolute;
  left: 0;
  color: var(--color-brand);
  font-weight: 700;
  animation: blink 1.5s infinite;
}

@keyframes blink {
  0%, 50% { opacity: 1; }
  51%, 100% { opacity: 0; }
}

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

.nav {
  display: flex;
  gap: var(--space-xs);
}

.nav a {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  text-decoration: none;
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  position: relative;
}

.nav a:hover {
  color: var(--color-text-primary);
  background: var(--color-bg-hover);
}

.nav a.active {
  color: var(--color-brand);
  background: var(--color-brand-subtle);
}

/* Theme Toggle */
.theme-toggle {
  background: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  padding: var(--space-sm);
  color: var(--color-text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
  line-height: 1;
}

.theme-toggle:hover {
  border-color: var(--color-brand);
  color: var(--color-brand);
}

.theme-toggle svg {
  width: 18px;
  height: 18px;
}

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

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

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

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

.mobile-menu-btn {
  display: none;
  background: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  padding: var(--space-sm);
  color: var(--color-text-primary);
  transition: all var(--transition-fast);
}

.mobile-menu-btn:hover {
  border-color: var(--color-brand);
  color: var(--color-brand);
}

/* ========================================
   Hero Section
   ======================================== */

.hero {
  padding: var(--space-4xl) 0;
  text-align: center;
  position: relative;
}

.hero::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, var(--color-brand-glow) 0%, transparent 70%);
  pointer-events: none;
  z-index: -1;
}

.hero h1 {
  font-family: var(--font-display);
  font-size: 3.5rem;
  font-weight: 700;
  letter-spacing: -2px;
  line-height: 1.1;
  margin-bottom: var(--space-lg);
  background: linear-gradient(135deg, var(--color-text-primary) 0%, var(--color-brand) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

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

/* ========================================
   Buttons
   ======================================== */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-lg);
  font-family: var(--font-body);
  font-size: 0.875rem;
  font-weight: 600;
  line-height: 1;
  text-decoration: none;
  border-radius: var(--radius-sm);
  border: none;
  cursor: pointer;
  transition: all var(--transition-base);
}

.btn-primary {
  background: var(--color-brand);
  color: var(--color-bg-primary);
  box-shadow: var(--shadow-glow);
}

.btn-primary:hover {
  background: var(--color-brand-dim);
  transform: translateY(-2px);
  box-shadow: 0 0 30px var(--color-brand-glow);
}

.btn-secondary {
  background: var(--color-bg-tertiary);
  color: var(--color-text-primary);
  border: 1px solid var(--color-border);
}

.btn-secondary:hover {
  border-color: var(--color-brand);
  color: var(--color-brand);
}

.btn-ghost {
  background: transparent;
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
}

.btn-ghost:hover {
  border-color: var(--color-brand);
  color: var(--color-brand);
  background: var(--color-brand-subtle);
}

/* ========================================
   Cards
   ======================================== */

.card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  transition: all var(--transition-base);
}

.card:hover {
  border-color: var(--color-border-hover);
  box-shadow: var(--shadow-md);
}

.card-title {
  font-family: var(--font-display);
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--space-md);
  color: var(--color-text-primary);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.card-text {
  color: var(--color-text-secondary);
  line-height: 1.8;
  font-size: 0.95rem;
}

/* Skills Grid */
.skills-grid {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.skill-group {
  display: flex;
  align-items: flex-start;
  gap: var(--space-md);
}

.skill-group-label {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-brand);
  min-width: 70px;
  padding: var(--space-xs) 0;
  text-align: right;
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
}

/* Timeline */
.timeline {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.timeline-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-md);
  padding: var(--space-md);
  border-radius: var(--radius-md);
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  transition: all var(--transition-base);
}

.timeline-item:hover {
  border-color: var(--color-border-brand);
}

.timeline-year {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-brand);
  white-space: nowrap;
  padding: var(--space-xs) var(--space-sm);
  background: var(--color-brand-subtle);
  border-radius: var(--radius-sm);
  line-height: 1.5;
}

.timeline-content {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-xs);
}

/* Project List */
.project-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.project-item {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-md);
  border-radius: var(--radius-md);
  text-decoration: none;
  color: inherit;
  border: 1px solid var(--color-border);
  transition: all var(--transition-base);
}

.project-item:hover {
  border-color: var(--color-brand);
  background: var(--color-bg-hover);
}

.project-item-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  background: var(--color-bg-tertiary);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-brand);
  flex-shrink: 0;
  border: 1px solid var(--color-border);
}

.project-item:hover .project-item-icon {
  background: var(--color-brand);
  color: var(--color-bg-primary);
  border-color: var(--color-brand);
}

.project-item-content {
  flex: 1;
  min-width: 0;
}

.project-item-title {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-text-primary);
  margin-bottom: 2px;
  font-family: var(--font-mono);
}

.project-item-desc {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  line-height: 1.5;
}

/* Contact List */
.contact-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.contact-item {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-md);
  border-radius: var(--radius-md);
  text-decoration: none;
  color: inherit;
  border: 1px solid var(--color-border);
  transition: all var(--transition-base);
}

.contact-item:hover {
  border-color: var(--color-brand);
  background: var(--color-bg-hover);
}

.contact-icon {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  background: var(--color-bg-tertiary);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-secondary);
  flex-shrink: 0;
}

.contact-item:hover .contact-icon {
  color: var(--color-brand);
}

.contact-label {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  font-family: var(--font-mono);
  min-width: 48px;
}

.contact-value {
  font-size: 0.9rem;
  color: var(--color-brand);
  font-family: var(--font-mono);
}

/* ========================================
   Article Cards
   ======================================== */

.article-card {
  display: block;
  text-decoration: none;
  color: inherit;
  padding: var(--space-lg);
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.article-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 3px;
  height: 100%;
  background: var(--color-brand);
  transform: scaleY(0);
  transition: transform var(--transition-base);
}

.article-card:hover {
  border-color: var(--color-border-brand);
  transform: translateX(4px);
  box-shadow: var(--shadow-md);
}

.article-card:hover::before {
  transform: scaleY(1);
}

.article-card h3 {
  font-family: var(--font-display);
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  letter-spacing: -0.3px;
  color: var(--color-text-primary);
}

.article-card p {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.article-meta {
  display: flex;
  gap: var(--space-md);
  margin-top: var(--space-md);
  font-size: 0.75rem;
  color: var(--color-text-muted);
  font-family: var(--font-mono);
}

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

/* ========================================
   Tags & Categories
   ======================================== */

.tag {
  display: inline-flex;
  align-items: center;
  padding: var(--space-xs) var(--space-sm);
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  background: var(--color-brand-subtle);
  color: var(--color-brand);
  font-family: var(--font-mono);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.category-pills {
  display: flex;
  gap: var(--space-sm);
  flex-wrap: wrap;
  margin-bottom: var(--space-xl);
}

.category-pill {
  padding: var(--space-sm) var(--space-md);
  font-size: 0.875rem;
  font-weight: 500;
  border-radius: var(--radius-full);
  border: 1px solid var(--color-border);
  background: var(--color-bg-secondary);
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-family: var(--font-mono);
}

.category-pill:hover {
  border-color: var(--color-brand);
  color: var(--color-brand);
  background: var(--color-brand-subtle);
}

.category-pill.active {
  background: var(--color-brand);
  color: var(--color-bg-primary);
  border-color: var(--color-brand);
  box-shadow: var(--shadow-glow);
}

/* ========================================
   Article List
   ======================================== */

.article-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

/* ========================================
   Article Detail Page
   ======================================== */

.article-header {
  padding: var(--space-3xl) 0;
  border-bottom: 1px solid var(--color-border);
  margin-bottom: var(--space-xl);
}

.article-header h1 {
  font-family: var(--font-display);
  font-size: 2.5rem;
  font-weight: 700;
  letter-spacing: -1px;
  line-height: 1.2;
  margin-bottom: var(--space-lg);
  color: var(--color-text-primary);
}

.article-stats {
  display: flex;
  gap: var(--space-md);
  font-size: 0.875rem;
  color: var(--color-text-muted);
  font-family: var(--font-mono);
}

.article-stats .stat-item {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.article-content {
  font-size: 1rem;
  line-height: 1.8;
  color: var(--color-text-primary);
}

.article-content h1,
.article-content h2,
.article-content h3,
.article-content h4 {
  font-family: var(--font-display);
  margin-top: var(--space-2xl);
  margin-bottom: var(--space-md);
  letter-spacing: -0.5px;
  color: var(--color-text-primary);
}

.article-content h1 { font-size: 2rem; }
.article-content h2 { 
  font-size: 1.5rem;
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--color-border);
}
.article-content h3 { font-size: 1.25rem; }
.article-content h4 { font-size: 1.125rem; }

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

.article-content a {
  color: var(--color-brand);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition-fast);
}

.article-content a:hover {
  border-bottom-color: var(--color-brand);
}

.article-content code {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  background: var(--color-bg-tertiary);
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  color: var(--color-brand);
}

.article-content pre {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  padding: var(--space-lg);
  border-radius: var(--radius-md);
  overflow-x: auto;
  margin: var(--space-lg) 0;
  position: relative;
}

.article-content pre::before {
  content: attr(data-lang);
  position: absolute;
  top: var(--space-sm);
  right: var(--space-sm);
  font-size: 0.75rem;
  color: var(--color-text-muted);
  font-family: var(--font-mono);
  text-transform: uppercase;
}

.article-content pre code {
  background: none;
  padding: 0;
  color: var(--color-text-primary);
}

.article-content blockquote {
  border-left: 3px solid var(--color-brand);
  padding-left: var(--space-lg);
  margin: var(--space-lg) 0;
  color: var(--color-text-secondary);
  font-style: italic;
  background: var(--color-brand-subtle);
  padding: var(--space-md) var(--space-lg);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

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

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

.article-content li::marker {
  color: var(--color-brand);
}

/* ========================================
   Tools Page
   ======================================== */

.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-md);
}

.tool-category {
  margin-bottom: var(--space-2xl);
}

.tool-category h2 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--color-border);
  color: var(--color-text-primary);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.tool-category h2::before {
  content: '#';
  color: var(--color-brand);
  font-family: var(--font-mono);
}

.tool-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-md);
  padding: var(--space-md);
  border-radius: var(--radius-md);
  text-decoration: none;
  color: inherit;
  transition: all var(--transition-base);
  border: 1px solid var(--color-border);
  background: var(--color-bg-card);
}

.tool-item:hover {
  border-color: var(--color-brand);
  background: var(--color-bg-hover);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.tool-item-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  background: var(--color-bg-tertiary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.875rem;
  font-weight: 700;
  flex-shrink: 0;
  color: var(--color-text-secondary);
  font-family: var(--font-mono);
  border: 1px solid var(--color-border);
}

.tool-item:hover .tool-item-icon {
  background: var(--color-brand);
  color: var(--color-bg-primary);
  border-color: var(--color-brand);
}

.tool-item-content {
  flex: 1;
  min-width: 0;
}

.tool-item-title {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-text-primary);
  margin-bottom: 2px;
}

.tool-item-desc {
  font-size: 0.75rem;
  color: var(--color-text-secondary);
  line-height: 1.5;
}

/* ========================================
   GitHub Projects
   ======================================== */

.github-projects-section {
  margin-top: var(--space-2xl);
}

.github-projects-section h2 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--color-border);
}

.github-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--space-md);
}

.github-card {
  display: block;
  padding: var(--space-lg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  text-decoration: none;
  color: inherit;
  transition: all var(--transition-base);
  background: var(--color-bg-card);
}

.github-card:hover {
  border-color: var(--color-brand);
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.github-card-header {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  margin-bottom: var(--space-md);
}

.github-card-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  background: var(--color-bg-tertiary);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-primary);
  font-size: 0.75rem;
  font-weight: 700;
  flex-shrink: 0;
  font-family: var(--font-mono);
  border: 1px solid var(--color-border);
}

.github-card:hover .github-card-icon {
  background: var(--color-brand);
  color: var(--color-bg-primary);
  border-color: var(--color-brand);
}

.github-card-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text-primary);
}

.github-card-desc {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.github-card-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  margin-top: var(--space-md);
  font-size: 0.875rem;
  color: var(--color-brand);
  font-weight: 500;
}

/* ========================================
   AI Platform Cards
   ======================================== */

.ai-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--space-md);
}

.ai-card {
  display: block;
  padding: var(--space-lg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  text-decoration: none;
  color: inherit;
  transition: all var(--transition-base);
  background: var(--color-bg-card);
}

.ai-card:hover {
  border-color: var(--color-brand);
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.ai-card-header {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  margin-bottom: var(--space-md);
}

.ai-card-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 0.75rem;
  font-weight: 700;
  flex-shrink: 0;
  font-family: var(--font-mono);
}

.ai-card:hover .ai-card-icon {
  background: var(--color-brand) !important;
}

.ai-card-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text-primary);
}

.ai-card-desc {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

/* ========================================
   Footer
   ======================================== */

.footer {
  padding: var(--space-2xl) 0;
  border-top: 1px solid var(--color-border);
  margin-top: var(--space-4xl);
  text-align: center;
  color: var(--color-text-muted);
  font-size: 0.875rem;
  font-family: var(--font-mono);
  transition: border-color var(--transition-base);
}

.footer p::before {
  content: '// ';
  color: var(--color-brand);
}

/* ========================================
   Section
   ======================================== */

.section {
  padding: var(--space-2xl) 0;
}

.section-title {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: var(--space-lg);
  letter-spacing: -0.5px;
  color: var(--color-text-primary);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.section-title::before {
  content: '#';
  color: var(--color-brand);
  font-family: var(--font-mono);
}

/* ========================================
   Empty State
   ======================================== */

.empty-state {
  text-align: center;
  padding: var(--space-4xl) var(--space-lg);
  color: var(--color-text-secondary);
}

.empty-state h3 {
  font-size: 1.25rem;
  margin-bottom: var(--space-sm);
  color: var(--color-text-primary);
}

/* ========================================
   Responsive Design
   ======================================== */

@media (max-width: 768px) {
  :root {
    font-size: 14px;
  }
  
  .header {
    padding: var(--space-sm) 0;
  }

  .header-inner {
    flex-direction: row;
    justify-content: space-between;
    align-items: center;
  }

  .logo {
    font-size: 1rem;
  }

  .mobile-menu-btn {
    display: flex;
  }

  .nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-bg-primary);
    flex-direction: column;
    gap: 0;
    padding: 0;
    border-top: 1px solid var(--color-border);
    box-shadow: var(--shadow-lg);
    display: none;
    z-index: 99;
  }

  .nav.active {
    display: flex;
  }

  .nav a {
    display: block;
    padding: var(--space-md);
    font-size: 0.875rem;
    border-bottom: 1px solid var(--color-border);
    text-align: left;
  }

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

  .nav a:hover {
    background: var(--color-bg-hover);
  }

  .hero {
    padding: var(--space-2xl) 0;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .hero p {
    font-size: 1rem;
  }

  .article-header h1 {
    font-size: 1.75rem;
  }

  .tools-grid,
  .github-grid,
  .ai-grid {
    grid-template-columns: 1fr;
  }
  
  .category-pills {
    gap: var(--space-xs);
  }
  
  .category-pill {
    padding: var(--space-xs) var(--space-sm);
    font-size: 0.75rem;
  }
}

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

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

@keyframes slideInRight {
  from {
    opacity: 0;
    transform: translateX(-20px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.article-card {
  animation: fadeInUp 0.4s ease forwards;
}

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

/* ========================================
   Scrollbar
   ======================================== */

::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: var(--color-bg-secondary);
}

::-webkit-scrollbar-thumb {
  background: var(--color-bg-tertiary);
  border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-text-muted);
}

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

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

.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); }