/* ========================================
   Ad Tech Blog - Modern Dark Mode Design
   ======================================== */

/* Import Google Fonts */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=Fira+Code:wght@400;500&display=swap');

/* ========================================
   CSS Variables & Theme System
   ======================================== */

:root {
  /* Dark Theme Colors */
  --bg-primary: #0a0e27;
  --bg-secondary: #161b33;
  --bg-tertiary: #1e2541;
  --bg-gradient: linear-gradient(135deg, #0a0e27 0%, #1a1f3a 100%);

  /* Accent Colors */
  --accent-primary: #00e5ff;
  --accent-secondary: #b026ff;
  --accent-gradient: linear-gradient(135deg, #b026ff 0%, #ff6b9d 100%);
  --accent-glow: rgba(0, 229, 255, 0.3);

  /* Text Colors */
  --text-primary: #ffffff;
  --text-secondary: #b8c5d6;
  --text-muted: #7a8ba3;

  /* UI Elements */
  --border-color: rgba(255, 255, 255, 0.1);
  --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 var(--accent-glow);

  /* Glassmorphism */
  --glass-bg: rgba(30, 37, 65, 0.7);
  --glass-border: rgba(255, 255, 255, 0.18);

  /* Transitions */
  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.5s ease;
}

[data-theme="light"] {
  --bg-primary: #f5f7fa;
  --bg-secondary: #ffffff;
  --bg-tertiary: #e8ecf1;
  --bg-gradient: linear-gradient(135deg, #f5f7fa 0%, #e8ecf1 100%);

  --accent-primary: #0099ff;
  --accent-secondary: #8b21d1;

  --text-primary: #1a1f36;
  --text-secondary: #4a5568;
  --text-muted: #718096;

  --border-color: rgba(0, 0, 0, 0.1);
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.15);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.2);

  --glass-bg: rgba(255, 255, 255, 0.7);
  --glass-border: rgba(0, 0, 0, 0.1);
}

/* ========================================
   Reset & Base Styles
   ======================================== */

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg-gradient);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  transition: background var(--transition-normal);
}

/* ========================================
   Typography
   ======================================== */

h1,
h2,
h3,
h4,
h5,
h6 {
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 1rem;
}

h1 {
  font-size: 3rem;
}

h2 {
  font-size: 2.25rem;
}

h3 {
  font-size: 1.75rem;
}

h4 {
  font-size: 1.5rem;
}

h5 {
  font-size: 1.25rem;
}

h6 {
  font-size: 1rem;
}

p {
  margin-bottom: 1rem;
  color: var(--text-secondary);
}

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

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

code {
  font-family: 'Fira Code', monospace;
  background: var(--bg-tertiary);
  padding: 0.2em 0.4em;
  border-radius: 4px;
  font-size: 0.9em;
}

pre {
  background: var(--bg-tertiary);
  padding: 1.5rem;
  border-radius: 8px;
  overflow-x: auto;
  margin-bottom: 1rem;
  border: 1px solid var(--border-color);
}

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

/* ========================================
   Header & Navigation
   ======================================== */

header {
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--glass-border);
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: var(--shadow-sm);
}

nav {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.5rem;
  font-weight: 800;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.nav-content {
  display: flex;
  align-items: center;
  gap: 2rem;
  flex: 1;
  justify-content: flex-end;
}

.nav-links {
  display: flex;
  gap: 2rem;
  align-items: center;
  list-style: none;
}

.nav-links a {
  color: var(--text-secondary);
  font-weight: 500;
  transition: color var(--transition-fast);
}

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

.nav-links a.active {
  color: var(--accent-primary);
  position: relative;
}

.nav-links a.active::after {
  content: "";
  position: absolute;
  bottom: -4px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--accent-primary);
  border-radius: 1px;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.btn-demo {
  padding: 0.5rem 1rem;
  background: rgba(0, 229, 255, 0.1);
  border: 1px solid var(--accent-primary);
  border-radius: 8px;
  color: var(--accent-primary);
  font-weight: 600;
  font-size: 0.9rem;
  transition: all var(--transition-fast);
}

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

/* Theme Toggle Button */
.theme-toggle {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 0.5rem 1rem;
  border-radius: 8px;
  cursor: pointer;
  font-size: 1.2rem;
  transition: all var(--transition-fast);
}

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

/* ========================================
   Container & Layout
   ======================================== */

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

.section {
  padding: 4rem 0;
}

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

.hero {
  text-align: center;
  padding: 6rem 0 4rem;
  background: radial-gradient(circle at 50% 0%, rgba(176, 38, 255, 0.15) 0%, transparent 50%);
}

.hero h1 {
  font-size: 3.5rem;
  margin-bottom: 1rem;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: fadeInUp 0.8s ease;
}

.hero p {
  font-size: 1.25rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto 2rem;
  animation: fadeInUp 0.8s ease 0.2s both;
}

/* ========================================
   Search & Filter Bar
   ======================================== */

.search-filter-bar {
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  padding: 2rem;
  margin-bottom: 3rem;
  box-shadow: var(--shadow-md);
  animation: fadeInUp 0.8s ease 0.4s both;
}

.search-box {
  position: relative;
  margin-bottom: 1.5rem;
}

.search-box input {
  width: 100%;
  padding: 1rem 1rem 1rem 3rem;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  color: var(--text-primary);
  font-size: 1rem;
  transition: all var(--transition-fast);
}

.search-box input:focus {
  outline: none;
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.search-box::before {
  content: "\1F50D";
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  font-size: 1.1rem;
  color: var(--text-muted);
  pointer-events: none;
  z-index: 1;
}

.filter-section h4 {
  font-size: 0.875rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

/* Category Navigation */
.category-nav {
  padding: 0.5rem 0 1.5rem;
}

.category-tabs {
  display: flex;
  justify-content: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.category-tab {
  padding: 0.65rem 1.4rem;
  color: var(--text-muted);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  border-radius: 12px;
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--glass-border);
  position: relative;
  letter-spacing: 0.02em;
}

.category-tab:hover {
  color: var(--text-primary);
  border-color: var(--accent-primary);
  transform: translateY(-2px);
  box-shadow: 0 4px 20px rgba(233, 69, 163, 0.15);
}

.category-tab.active {
  color: white;
  background: linear-gradient(135deg, rgba(233, 69, 163, 0.2), rgba(104, 109, 224, 0.2));
  border-color: var(--accent-primary);
  box-shadow: 0 0 20px rgba(233, 69, 163, 0.2), inset 0 0 20px rgba(233, 69, 163, 0.05);
}

.filter-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.filter-tag {
  padding: 0.5rem 1rem;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 20px;
  color: var(--text-secondary);
  font-size: 0.875rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  font-weight: 500;
}

.filter-tag:hover {
  background: var(--accent-primary);
  color: var(--bg-primary);
  border-color: var(--accent-primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow-glow);
}

.filter-tag.active {
  background: var(--accent-gradient);
  color: white;
  border-color: transparent;
  box-shadow: var(--shadow-glow);
}

/* ========================================
   Blog Posts Grid
   ======================================== */


/* ========================================
   Posts Grid (unchanged definition)
   ======================================== */

.posts-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
  gap: 2rem;
  margin-bottom: 3rem;
}

.post-card {
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  padding: 2rem;
  transition: all var(--transition-normal);
  cursor: pointer;
  animation: fadeInUp 0.6s ease both;
  display: flex;
  flex-direction: column;
}

.post-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-lg);
  border-color: var(--accent-primary);
}

.post-card-category {
  display: inline-block;
  padding: 0.25rem 0.7rem;
  background: var(--accent-gradient);
  border-radius: 20px;
  font-size: 0.7rem;
  font-weight: 600;
  color: white;
  letter-spacing: 0.03em;
  width: fit-content;
  margin-bottom: 0.85rem;
}

.post-card-excerpt {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 1.25rem;
  flex: 1;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.post-card-footer {
  margin-top: auto;
  padding-top: 0.75rem;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
}

.post-meta {
  display: flex;
  gap: 0.4rem;
  margin-bottom: 0.75rem;
  align-items: center;
}

.post-meta-sep {
  color: var(--text-muted);
  font-size: 0.75rem;
}

.post-date,
.post-read-time {
  color: var(--text-muted);
  font-size: 0.75rem;
  display: flex;
  align-items: center;
}

.post-card h3 {
  font-size: 1.2rem;
  margin-bottom: 0.65rem;
  color: var(--text-primary);
  transition: color var(--transition-fast);
  line-height: 1.45;
  font-weight: 700;
}

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

.post-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 0;
}

.tag {
  padding: 0.25rem 0.75rem;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  font-size: 0.75rem;
  color: var(--accent-primary);
  font-weight: 500;
  transition: all var(--transition-fast);
  cursor: pointer;
}

.tag:hover {
  background: var(--accent-primary);
  color: var(--bg-primary);
  transform: scale(1.05);
}

/* ========================================
   Post Detail Page
   ======================================== */

.post-header {
  text-align: center;
  padding: 4rem 0 0.5rem;
  max-width: 1100px;
  margin: 0 auto;
}

.post-header h1 {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.post-categories {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
  margin-bottom: 1rem;
  flex-wrap: wrap;
}

.category-badge {
  padding: 0.5rem 1rem;
  background: var(--accent-gradient);
  border-radius: 20px;
  font-size: 0.875rem;
  font-weight: 600;
  color: white;
}

/* Post header tag pills (replaces category badge, styled same but clickable) */
.post-header-tags {
  display: flex;
  gap: 0.6rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-top: 0.85rem;
  margin-bottom: 0.5rem;
}

.post-header-tag {
  display: inline-block;
  padding: 0.4rem 1rem;
  background: var(--accent-gradient);
  border-radius: 20px;
  font-size: 0.8rem;
  font-weight: 600;
  color: white;
  cursor: pointer;
  transition: opacity var(--transition-fast), transform var(--transition-fast);
}

.post-header-tag:hover {
  opacity: 0.8;
  transform: translateY(-1px);
}

.post-content {
  max-width: 1100px;
  margin: 0 auto;
  padding: 3rem 2.5rem;
  background: rgba(22, 27, 51, 0.92);
  backdrop-filter: blur(10px);
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  box-shadow: var(--shadow-md);
}

[data-theme="light"] .post-content {
  background: rgba(255, 255, 255, 0.92);
}

/* --- Improved Markdown Styling --- */

.post-content h1,
.post-content h2,
.post-content h3,
.post-content h4,
.post-content h5,
.post-content h6 {
  margin-bottom: 1rem;
  color: var(--text-primary);
}

.post-content h2 {
  font-size: 1.75rem;
  border-bottom: 1px solid var(--border-color);
  border-left: 4px solid var(--accent-primary);
  padding: 0.5rem 0 0.6rem 1rem;
  color: var(--accent-primary);
  margin-left: -1rem;
  margin-top: 3.5rem;
}

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

.post-content h3 {
  font-size: 1.3rem;
  color: #b8c5d6;
  border-left: 3px solid rgba(176, 38, 255, 0.6);
  padding-left: 0.75rem;
  margin-left: -0.75rem;
  margin-top: 2.5rem;
  font-weight: 600;
}

.post-content h4 {
  font-size: 1.1rem;
  color: var(--text-primary);
  font-weight: 600;
  margin-top: 2rem;
}

[data-theme="light"] .post-content h3 {
  color: #4a5568;
}

.post-content p {
  margin-bottom: 1.25rem;
  line-height: 1.85;
  font-size: 1.0625rem;
  color: #b8c0d0;
}

[data-theme="light"] .post-content p {
  color: var(--text-secondary);
}

.post-content ul,
.post-content ol {
  margin-bottom: 1.4rem;
  padding-left: 2rem;
  color: #b8c0d0;
}

[data-theme="light"] .post-content ul,
[data-theme="light"] .post-content ol {
  color: var(--text-secondary);
}

.post-content li {
  margin-bottom: 0.5rem;
  line-height: 1.75;
}

.post-content li > ul,
.post-content li > ol {
  margin-top: 0.4rem;
  margin-bottom: 0.4rem;
}

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

.post-content blockquote {
  border-left: 4px solid var(--accent-primary);
  padding: 1.1rem 1.5rem;
  margin: 2rem 0;
  background: linear-gradient(90deg, rgba(0, 229, 255, 0.08) 0%, rgba(30, 37, 65, 0.8) 100%);
  border-radius: 0 8px 8px 0;
  color: #d0d8e4;
  font-style: normal;
}

[data-theme="light"] .post-content blockquote {
  background: linear-gradient(90deg, rgba(0, 153, 255, 0.06) 0%, var(--bg-tertiary) 100%);
  color: var(--text-secondary);
}

.post-content blockquote p {
  margin-bottom: 0;
}

.post-content .code-block-wrapper {
  position: relative;
  margin: 2rem 0;
}

.post-content .code-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: #21222c;
  border: 1px solid var(--border-color);
  border-bottom: none;
  border-radius: 8px 8px 0 0;
  padding: 0.5rem 1rem;
}

.post-content .code-lang {
  font-family: 'Fira Code', monospace;
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.post-content .copy-btn {
  background: transparent;
  border: 1px solid var(--border-color);
  border-radius: 4px;
  color: var(--text-muted);
  font-size: 0.75rem;
  padding: 0.25rem 0.6rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  font-family: 'Inter', sans-serif;
}

.post-content .copy-btn:hover {
  background: var(--accent-primary);
  color: var(--bg-primary);
  border-color: var(--accent-primary);
}

.post-content .copy-btn.copied {
  color: #4ade80;
  border-color: #4ade80;
}

.post-content pre {
  background: #1a1b26;
  padding: 1.5rem;
  border-radius: 8px;
  overflow-x: auto;
  margin: 0;
  border: 1px solid var(--border-color);
  box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.3);
}

.post-content .code-block-wrapper pre {
  border-radius: 0 0 8px 8px;
}

[data-theme="light"] .post-content .code-header {
  background: #e8ecf1;
}

[data-theme="light"] .post-content pre {
  background: #fafbfc !important;
  box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.06);
}

[data-theme="light"] .post-content pre code {
  background: transparent;
  color: #383a42;
}

[data-theme="light"] .post-content pre code.hljs {
  background: transparent !important;
  color: #383a42;
}

[data-theme="light"] .post-content .hljs-keyword,
[data-theme="light"] .post-content .hljs-selector-tag,
[data-theme="light"] .post-content .hljs-type { color: #a626a4; }

[data-theme="light"] .post-content .hljs-string,
[data-theme="light"] .post-content .hljs-attr { color: #50a14f; }

[data-theme="light"] .post-content .hljs-number,
[data-theme="light"] .post-content .hljs-literal { color: #986801; }

[data-theme="light"] .post-content .hljs-comment { color: #a0a1a7; }

[data-theme="light"] .post-content .hljs-built_in,
[data-theme="light"] .post-content .hljs-title { color: #4078f2; }

[data-theme="light"] .post-content .hljs-function { color: #4078f2; }

[data-theme="light"] .post-content .hljs-params { color: #383a42; }

[data-theme="light"] .post-content code {
  background: rgba(0, 0, 0, 0.06);
}

[data-theme="light"] .post-content .copy-btn {
  color: var(--text-muted);
  border-color: var(--border-color);
}

[data-theme="light"] .post-content .code-lang {
  color: var(--text-muted);
}

.post-content code {
  font-family: 'Fira Code', monospace;
  background: rgba(255, 255, 255, 0.12);
  padding: 0.2em 0.45em;
  border-radius: 4px;
  font-size: 0.875em;
  color: #e2b96f;
  border: 1px solid rgba(255, 255, 255, 0.1);
}

.post-content pre code {
  background: none;
  padding: 0;
  color: inherit;
  font-size: 0.9rem;
  border: none;
}

/* Mermaid Diagrams */
.post-content pre.mermaid {
  background: transparent;
  border: none;
  box-shadow: none;
  text-align: center;
  margin: 2rem 0;
  padding: 1.5rem 1rem;
  overflow-x: auto;
}

.post-content img {
  max-width: 100%;
  height: auto;
  border-radius: 8px;
  margin: 2rem auto;
  display: block;
  box-shadow: var(--shadow-md);
}

.post-content .table-wrapper {
  overflow-x: auto;
  margin: 2rem 0;
  border-radius: 8px;
  border: 1px solid var(--border-color);
}

.post-content table {
  width: 100%;
  border-collapse: collapse;
  background: var(--bg-tertiary);
  border-radius: 8px;
  overflow: hidden;
  margin: 0;
}

.post-content th,
.post-content td {
  padding: 0.875rem 1rem;
  border-bottom: 1px solid var(--border-color);
  text-align: left;
}

.post-content td {
  white-space: normal;
  color: #d0d8e4;
}

[data-theme="light"] .post-content td {
  color: var(--text-secondary);
}

.post-content th {
  background: rgba(0, 229, 255, 0.07);
  font-weight: 600;
  color: var(--accent-primary);
  font-size: 0.875rem;
  letter-spacing: 0.02em;
}

.post-content tr:nth-child(even) td {
  background: rgba(255, 255, 255, 0.025);
}

.post-content tr:hover td {
  background: rgba(0, 229, 255, 0.05);
}

.post-content tr:last-child td {
  border-bottom: none;
}

.post-content hr {
  border: 0;
  height: 1px;
  background: var(--border-color);
  margin: 3rem 0;
}

.post-content strong {
  color: var(--text-primary);
  font-weight: 700;
}

.post-content a {
  text-decoration: underline;
  text-underline-offset: 4px;
}

/* ========================================
   Post Navigation (Prev / Next)
   ======================================== */

.post-nav {
  display: flex;
  justify-content: space-between;
  gap: 1.5rem;
  max-width: 1100px;
  margin: 3rem auto 0;
  padding: 0 2rem;
}

.post-nav-link {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  padding: 1.25rem 1.5rem;
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  flex: 1;
  max-width: 48%;
  transition: all var(--transition-fast);
  text-decoration: none;
}

.post-nav-link:hover {
  border-color: var(--accent-primary);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

.post-nav-next {
  text-align: right;
  margin-left: auto;
}

.post-nav-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  font-weight: 600;
}

.post-nav-title {
  font-size: 0.95rem;
  color: var(--accent-primary);
  font-weight: 600;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* ========================================
   Related Posts
   ======================================== */

.related-posts {
  max-width: 1100px;
  margin: 3rem auto 0;
  padding: 0 2rem;
}

.related-posts-title {
  font-size: 1.25rem;
  color: var(--text-primary);
  margin-bottom: 1.25rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border-color);
}

.related-posts-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
}

.related-post-card {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  padding: 1.25rem;
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  transition: all var(--transition-fast);
  text-decoration: none;
}

.related-post-card:hover {
  border-color: var(--accent-primary);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

.related-post-date {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.related-post-name {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--accent-primary);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.related-post-excerpt {
  font-size: 0.8rem;
  color: var(--text-secondary);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* ========================================
   Reading Progress Bar
   ======================================== */

.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  width: 0%;
  background: var(--accent-gradient);
  z-index: 1100;
  transition: width 0.1s linear;
  box-shadow: 0 0 8px var(--accent-glow);
}

/* ========================================
   Post TOC Sidebar
   ======================================== */

.toc-back-link {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 1.5rem;
  color: var(--text-muted);
  font-size: 0.85rem;
  font-weight: 500;
  transition: color var(--transition-fast);
  margin-bottom: 0.5rem;
}

.toc-back-link:hover {
  color: var(--accent-primary);
  text-decoration: none;
}

.toc-list {
  padding: 0 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.toc-item {
  display: block;
  padding: 0.45rem 0.75rem;
  color: #c0c8d8;
  font-size: 0.82rem;
  border-radius: 6px;
  transition: all var(--transition-fast);
  line-height: 1.4;
  border-left: 2px solid transparent;
  word-break: break-word;
}

[data-theme="light"] .toc-item {
  color: var(--text-secondary);
}

.toc-item:hover {
  color: var(--accent-primary);
  background: rgba(255, 255, 255, 0.06);
  text-decoration: none;
  border-left-color: var(--accent-primary);
}

[data-theme="light"] .toc-item:hover {
  background: var(--bg-tertiary);
}

.toc-item.active {
  color: var(--accent-primary);
  background: rgba(255, 255, 255, 0.06);
  border-left-color: var(--accent-primary);
  font-weight: 600;
}

[data-theme="light"] .toc-item.active {
  background: var(--bg-tertiary);
}

.toc-item.toc-h3 {
  padding-left: 1.5rem;
  font-size: 0.78rem;
  color: #a0aabb;
}

[data-theme="light"] .toc-item.toc-h3 {
  color: var(--text-muted);
}

.toc-item.toc-h3:hover,
.toc-item.toc-h3.active {
  color: var(--accent-primary);
}


/* ========================================
   About Page
   ======================================== */

.about-content {
  max-width: 1100px;
  margin: 0 auto;
  padding: 3rem 2rem;
}

.about-hero {
  text-align: center;
  padding: 4rem 0 2rem;
}

.about-section {
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  padding: 2.5rem 3rem;
  margin-bottom: 2rem;
  box-shadow: var(--shadow-md);
  transition: all var(--transition-normal);
}

.about-section:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--accent-primary);
}

.about-section h2 {
  color: var(--accent-primary);
  margin-bottom: 1.25rem;
}

.about-section p {
  line-height: 1.8;
  color: var(--text-secondary);
  margin-bottom: 0.75rem;
}

.about-section ul {
  padding-left: 1.5rem;
  margin-top: 0.75rem;
}

.about-section li {
  margin-bottom: 0.6rem;
  line-height: 1.7;
  color: var(--text-secondary);
}

@media (max-width: 768px) {
  .about-section {
    padding: 1.75rem 1.5rem;
  }
}

.contact-links {
  display: flex;
  gap: 1rem;
  margin-top: 1.5rem;
  flex-wrap: wrap;
}

.contact-btn {
  padding: 0.75rem 1.5rem;
  background: var(--accent-gradient);
  border-radius: 8px;
  color: white;
  font-weight: 600;
  transition: all var(--transition-fast);
  display: inline-block;
  text-decoration: none;
}

.contact-btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-glow);
  color: white;
}

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

footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 3rem 0;
  margin-top: 4rem;
  text-align: center;
}

.footer-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-bottom: 1rem;
  flex-wrap: wrap;
}

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

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

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulse {

  0%,
  100% {
    opacity: 1;
  }

  50% {
    opacity: 0.5;
  }
}

.loading {
  animation: pulse 1.5s ease-in-out infinite;
  text-align: center;
  padding: 2rem;
  color: var(--accent-primary);
  font-size: 1.2rem;
}

/* ========================================
   Sidebar Navigation
   ======================================== */

.sidebar {
  position: fixed;
  left: 0;
  top: 70px;
  /* Below header */
  width: 280px;
  height: calc(100vh - 70px);
  background: rgba(22, 27, 51, 0.95);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-right: 1px solid var(--glass-border);
  overflow-y: auto;
  z-index: 900;
  transition: transform var(--transition-normal);
  padding: 2rem 0;
}

[data-theme="light"] .sidebar {
  background: rgba(255, 255, 255, 0.95);
}

.sidebar::-webkit-scrollbar {
  width: 6px;
}

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

.sidebar::-webkit-scrollbar-thumb {
  background: var(--accent-primary);
  border-radius: 3px;
}

.sidebar-header {
  padding: 0 1.5rem 1rem;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 1rem;
}

.sidebar-header h3 {
  font-size: 1.125rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--text-primary);
  margin: 0;
}

.sidebar-nav {
  padding: 0 1rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.sidebar-category {
  margin-bottom: 0;
  display: block;
  width: 100%;
  background: var(--bg-secondary);
  border-radius: 10px;
  overflow: hidden;
  transition: all var(--transition-normal);
  border: 1px solid var(--border-color);
}

.sidebar-category:hover {
  box-shadow: var(--shadow-sm);
}

.category-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1rem 1rem;
  color: var(--text-primary);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  user-select: none;
  background: transparent;
  letter-spacing: 0.02em;
}

.category-header:hover {
  background: var(--bg-tertiary);
  color: var(--accent-primary);
}

.category-icon {
  font-size: 0.7rem;
  transition: transform var(--transition-fast);
  display: inline-block;
  color: var(--text-muted);
  min-width: 12px;
}

.sidebar-category.collapsed .category-icon {
  transform: rotate(-90deg);
}

.category-posts {
  margin-left: 0;
  padding: 0 1rem 1rem 1rem;
  max-height: 1000px;
  overflow: hidden;
  transition: max-height var(--transition-normal), opacity var(--transition-normal), padding var(--transition-normal);
}

.sidebar-category.collapsed .category-posts {
  max-height: 0;
  opacity: 0;
  padding: 0 1rem;
}

.sidebar-post-link {
  display: block;
  padding: 0.7rem 1rem;
  color: var(--text-secondary);
  font-size: 0.85rem;
  border-radius: 6px;
  transition: all var(--transition-fast);
  margin-bottom: 0.5rem;
  position: relative;
  word-wrap: break-word;
  overflow-wrap: break-word;
  white-space: normal;
  line-height: 1.5;
  border: 1px solid transparent;
  background: transparent;
  font-weight: 400;
}

.sidebar-post-link:hover {
  background: var(--bg-tertiary);
  color: var(--accent-primary);
  border-color: var(--border-color);
  transform: translateX(4px);
  font-weight: 500;
}

.sidebar-post-link.active {
  background: var(--bg-tertiary);
  color: var(--accent-primary);
  font-weight: 600;
  border-color: var(--accent-primary);
}

.sidebar-post-link.active::before {
  display: none;
}

/* Sidebar Toggle Button (Mobile) */
.sidebar-toggle {
  position: fixed;
  left: 1rem;
  bottom: 1rem;
  width: 50px;
  height: 50px;
  background: var(--accent-gradient);
  border: none;
  border-radius: 50%;
  color: white;
  font-size: 1.5rem;
  cursor: pointer;
  box-shadow: var(--shadow-lg);
  z-index: 1001;
  display: none;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
}

.sidebar-toggle:hover {
  transform: scale(1.1);
  box-shadow: var(--shadow-glow);
}

/* ========================================
   Media Queries
   ======================================== */

@media (max-width: 1024px) {
  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.visible {
    transform: translateX(0);
  }

  .with-sidebar {
    margin-left: 0;
    width: 100%;
  }

  .sidebar-toggle {
    display: flex;
  }
}

@media (min-width: 1025px) {
  .with-sidebar {
    margin-left: 280px;
    width: calc(100% - 280px);
  }

  .sidebar {
    transform: translateX(0);
  }
}

@media (max-width: 768px) {
  h1 {
    font-size: 2.5rem;
  }

  h2 {
    font-size: 2rem;
  }

  h3 {
    font-size: 1.4rem;
  }

  h4 {
    font-size: 1.25rem;
  }

  h5 {
    font-size: 1.1rem;
  }

  h6 {
    font-size: 0.95rem;
  }

  .hero {
    padding: 4rem 0 2rem;
  }

  .hero h1 {
    font-size: 2.5rem;
  }

  .search-filter-bar {
    padding: 1.5rem;
  }

  .posts-grid {
    grid-template-columns: 1fr;
  }

  .post-content {
    padding: 2rem 1.5rem;
  }

  .nav-links {
    gap: 1rem;
  }

  .nav-content {
    gap: 1rem;
  }

  .btn-demo {
    padding: 0.4rem 0.8rem;
    font-size: 0.8rem;
  }

  .post-nav {
    flex-direction: column;
  }

  .post-nav-link {
    max-width: 100%;
  }

  .related-posts-grid {
    grid-template-columns: 1fr;
  }

  .post-content img {
    margin: 1rem auto;
  }
}

/* ========================================
   Accessibility
   ======================================== */

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

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

/* ========================================
   Custom Chart Components
   ======================================== */

/* --- Layer Diagram (Architecture) --- */
.chart-layer {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 24px;
  background: var(--bg-secondary);
  border-radius: 16px;
  border: 1px solid var(--border-color);
  margin: 2rem 0;
  overflow-x: auto;
}

.chart-layer-title {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.chart-layer-row {
  display: flex;
  gap: 10px;
  align-items: stretch;
  min-height: 64px;
}

.chart-layer-group {
  flex: 1;
  min-width: 0;
  background: var(--bg-tertiary);
  border-radius: 12px;
  padding: 14px 16px;
  border: 1px solid var(--border-color);
  transition: var(--transition-fast);
  position: relative;
}

.chart-layer-group:hover {
  border-color: var(--accent-primary);
  box-shadow: 0 0 12px rgba(0, 229, 255, 0.15);
  transform: translateY(-1px);
}

.chart-layer-group-label {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.chart-layer-items {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.chart-layer-item {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  border-radius: 8px;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text-primary);
  white-space: nowrap;
}

.chart-layer-item.blue { background: rgba(54, 162, 235, 0.2); border: 1px solid rgba(54, 162, 235, 0.4); }
.chart-layer-item.cyan { background: rgba(0, 229, 255, 0.15); border: 1px solid rgba(0, 229, 255, 0.3); }
.chart-layer-item.purple { background: rgba(176, 38, 255, 0.2); border: 1px solid rgba(176, 38, 255, 0.4); }
.chart-layer-item.pink { background: rgba(255, 99, 132, 0.2); border: 1px solid rgba(255, 99, 132, 0.4); }
.chart-layer-item.orange { background: rgba(255, 159, 64, 0.2); border: 1px solid rgba(255, 159, 64, 0.4); }
.chart-layer-item.yellow { background: rgba(255, 206, 86, 0.2); border: 1px solid rgba(255, 206, 86, 0.5); color: var(--text-primary); }
.chart-layer-item.green { background: rgba(75, 192, 192, 0.2); border: 1px solid rgba(75, 192, 192, 0.4); }

.chart-layer-arrow {
  display: flex;
  justify-content: center;
  align-items: center;
  color: var(--text-muted);
  font-size: 1.4rem;
  padding: 2px 0;
}

/* --- Timeline (Horizontal) --- */
.chart-timeline {
  padding: 24px;
  background: var(--bg-secondary);
  border-radius: 16px;
  border: 1px solid var(--border-color);
  margin: 2rem 0;
  overflow-x: auto;
}

.chart-timeline-bar {
  position: relative;
  height: 52px;
  background: var(--bg-tertiary);
  border-radius: 10px;
  margin: 16px 0 8px;
  display: flex;
  align-items: center;
  overflow: hidden;
}

.chart-timeline-segment {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 600;
  color: #fff;
  padding: 0 8px;
  position: relative;
  white-space: nowrap;
  transition: var(--transition-fast);
  cursor: default;
}

.chart-timeline-segment:hover {
  filter: brightness(1.2);
}

.chart-timeline-segment.blue { background: rgba(54, 162, 235, 0.7); }
.chart-timeline-segment.cyan { background: rgba(0, 229, 255, 0.5); }
.chart-timeline-segment.purple { background: rgba(176, 38, 255, 0.6); }
.chart-timeline-segment.pink { background: rgba(255, 99, 132, 0.6); }
.chart-timeline-segment.orange { background: rgba(255, 159, 64, 0.6); }
.chart-timeline-segment.green { background: rgba(75, 192, 192, 0.6); }

.chart-timeline-labels {
  display: flex;
  justify-content: space-between;
  font-size: 0.7rem;
  color: var(--text-muted);
  padding: 0 4px;
}

.chart-timeline-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 16px;
  padding-top: 12px;
  border-top: 1px solid var(--border-color);
}

.chart-timeline-legend-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.78rem;
  color: var(--text-secondary);
}

.chart-timeline-legend-dot {
  width: 10px;
  height: 10px;
  border-radius: 3px;
  flex-shrink: 0;
}

/* --- Comparison Cards --- */
.chart-cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin: 2rem 0;
}

.chart-card {
  background: var(--bg-secondary);
  border-radius: 16px;
  border: 1px solid var(--border-color);
  padding: 20px;
  transition: var(--transition-fast);
  display: flex;
  flex-direction: column;
}

.chart-card:hover {
  border-color: var(--accent-primary);
  box-shadow: 0 0 16px rgba(0, 229, 255, 0.1);
  transform: translateY(-2px);
}

.chart-card-header {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
}

.chart-card-icon {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  flex-shrink: 0;
}

.chart-card-icon.yellow { background: rgba(255, 206, 86, 0.2); }
.chart-card-icon.orange { background: rgba(255, 159, 64, 0.2); }
.chart-card-icon.green { background: rgba(75, 192, 192, 0.2); }
.chart-card-icon.blue { background: rgba(54, 162, 235, 0.2); }
.chart-card-icon.pink { background: rgba(255, 99, 132, 0.2); }

.chart-card-name {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-primary);
}

.chart-card-subtitle {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.chart-card-body {
  flex: 1;
}

.chart-card-row {
  display: flex;
  justify-content: space-between;
  padding: 8px 0;
  border-bottom: 1px solid var(--border-color);
  font-size: 0.82rem;
}

.chart-card-row:last-child {
  border-bottom: none;
}

.chart-card-row-label {
  color: var(--text-muted);
  font-weight: 500;
}

.chart-card-row-value {
  color: var(--text-primary);
  font-weight: 600;
  text-align: right;
}

.chart-card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  margin-top: 12px;
}

.chart-card-tag {
  font-size: 0.7rem;
  padding: 3px 8px;
  border-radius: 6px;
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
}

/* --- Step Flow (Vertical) --- */
.chart-steps {
  display: flex;
  flex-direction: column;
  gap: 0;
  margin: 2rem 0;
  padding: 24px;
  background: var(--bg-secondary);
  border-radius: 16px;
  border: 1px solid var(--border-color);
}

.chart-step {
  display: flex;
  gap: 16px;
  align-items: flex-start;
  padding: 16px 0;
  position: relative;
}

.chart-step:not(:last-child) {
  border-bottom: none;
}

.chart-step-indicator {
  display: flex;
  flex-direction: column;
  align-items: center;
  flex-shrink: 0;
  width: 40px;
}

.chart-step-dot {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.85rem;
  font-weight: 700;
  color: #fff;
  flex-shrink: 0;
}

.chart-step-dot.green { background: rgba(75, 192, 192, 0.8); }
.chart-step-dot.yellow { background: rgba(255, 206, 86, 0.8); color: #333; }
.chart-step-dot.orange { background: rgba(255, 159, 64, 0.8); }
.chart-step-dot.pink { background: rgba(255, 99, 132, 0.8); }
.chart-step-dot.blue { background: rgba(54, 162, 235, 0.8); }

.chart-step-line {
  width: 2px;
  flex: 1;
  min-height: 16px;
  background: var(--border-color);
  margin-top: 4px;
}

.chart-step-content {
  flex: 1;
  min-width: 0;
}

.chart-step-title {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.chart-step-desc {
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.chart-step-badge {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 6px;
  margin-top: 6px;
}

.chart-step-badge.green { background: rgba(75, 192, 192, 0.2); color: #4bc0c0; }
.chart-step-badge.yellow { background: rgba(255, 206, 86, 0.2); color: #ffd740; }
.chart-step-badge.orange { background: rgba(255, 159, 64, 0.2); color: #ff9f40; }
.chart-step-badge.pink { background: rgba(255, 99, 132, 0.2); color: #ff6384; }
.chart-step-badge.blue { background: rgba(54, 162, 235, 0.2); color: #36a2eb; }

/* --- Architecture Diagram --- */
.chart-arch {
  padding: 24px;
  background: var(--bg-secondary);
  border-radius: 16px;
  border: 1px solid var(--border-color);
  margin: 2rem 0;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.chart-arch-section {
  background: var(--bg-tertiary);
  border-radius: 12px;
  padding: 16px;
  border: 1px solid var(--border-color);
  transition: var(--transition-fast);
}

.chart-arch-section:hover {
  border-color: var(--accent-primary);
  box-shadow: 0 0 12px rgba(0, 229, 255, 0.1);
}

.chart-arch-section-header {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
}

.chart-arch-section-icon {
  font-size: 1.1rem;
}

.chart-arch-section-title {
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.chart-arch-section-title.purple { color: #b026ff; }
.chart-arch-section-title.blue { color: #36a2eb; }
.chart-arch-section-title.orange { color: #ff9f40; }
.chart-arch-section-title.pink { color: #ff6384; }

.chart-arch-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 8px;
}

.chart-arch-node {
  background: var(--bg-secondary);
  border-radius: 8px;
  padding: 10px 12px;
  border: 1px solid var(--border-color);
  text-align: center;
}

.chart-arch-node-name {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-primary);
}

.chart-arch-node-desc {
  font-size: 0.7rem;
  color: var(--text-muted);
  margin-top: 2px;
}

.chart-arch-connector {
  display: flex;
  justify-content: center;
  align-items: center;
  color: var(--text-muted);
  font-size: 1.2rem;
  padding: 2px 0;
}

/* --- Chart.js Container --- */
.chart-js-container {
  background: var(--bg-secondary);
  border-radius: 16px;
  border: 1px solid var(--border-color);
  padding: 24px;
  margin: 2rem 0;
}

.chart-js-container canvas {
  max-height: 350px;
}

/* --- Responsive --- */
@media (max-width: 768px) {
  .chart-cards {
    grid-template-columns: 1fr;
  }

  .chart-layer-row {
    flex-direction: column;
  }

  .chart-timeline {
    min-width: 500px;
  }

  .chart-arch-grid {
    grid-template-columns: 1fr 1fr;
  }
}