/* blog.css - Notion Design System for ai-literacy */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap');

:root {
  /* Notion Color Palette */
  --bg-primary: #f6f5f4; /* Warm White */
  --bg-surface: #ffffff; /* Pure White */
  --text-primary: rgba(0, 0, 0, 0.95); /* Near-Black */
  --text-secondary: rgba(0, 0, 0, 0.65);
  --text-tertiary: rgba(0, 0, 0, 0.45);
  --accent: #0075de; /* Notion Blue */
  --accent-hover: #005fb8;
  --border: rgba(0, 0, 0, 0.1); /* Whisper Border */
  --border-hover: rgba(0, 0, 0, 0.2);
  
  /* Shadows - 4-5 layer low opacity stack */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 2px 4px rgba(0, 0, 0, 0.04), 0 4px 8px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 4px 8px rgba(0, 0, 0, 0.04), 0 8px 16px rgba(0, 0, 0, 0.04), 0 16px 32px rgba(0, 0, 0, 0.04);
  --shadow-card: 0 1px 2px rgba(0, 0, 0, 0.04), 0 2px 4px rgba(0, 0, 0, 0.04), 0 4px 8px rgba(0, 0, 0, 0.04);
  
  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  --base-size: 16px;
  --line-height: 1.6;
  
  /* Spacing */
  --space-xs: 8px;
  --space-sm: 16px;
  --space-md: 24px;
  --space-lg: 32px;
  --space-xl: 48px;
  --space-2xl: 64px;
  --space-3xl: 96px;
  
  /* Layout */
  --max-width: 1200px;
  --content-width: 720px;
  --sidebar-width: 280px;
  
  /* Borders */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  
  /* Transitions */
  --transition: 0.2s ease;
}

/* ---- Dark Mode ---- */
@media (prefers-color-scheme: dark) {
  :root {
    --bg-primary: #1e1e1e;
    --bg-surface: #2a2a2a;
    --text-primary: rgba(255, 255, 255, 0.95);
    --text-secondary: rgba(255, 255, 255, 0.65);
    --text-tertiary: rgba(255, 255, 255, 0.45);
    --border: rgba(255, 255, 255, 0.1);
    --border-hover: rgba(255, 255, 255, 0.2);
  }
}

/* ---- Reset ---- */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; font-size: var(--base-size); }

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: var(--line-height);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

/* ---- Reading Progress Bar ---- */
.reading-progress {
  position: fixed; top: 0; left: 0;
  width: 0%; height: 3px;
  background: var(--accent);
  z-index: 1000;
  transition: width 0.1s linear;
}

/* ---- Container ---- */
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 var(--space-md); }

/* ============ HEADER ============ */
.header {
  position: sticky; top: 0; z-index: 100;
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border);
  padding: 0;
}

.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 56px;
}

.logo { display: flex; flex-direction: column; text-decoration: none; }
.logo:hover { text-decoration: none; }

.logo-main {
  font-family: var(--font-sans);
  font-size: 1.1rem; font-weight: 600;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}
.logo-main span { color: var(--accent); }

.logo-sub {
  font-family: var(--font-sans);
  font-size: 0.65rem; color: var(--text-tertiary);
  letter-spacing: 0.05em; text-transform: uppercase;
}

.nav { display: flex; gap: var(--space-xs); align-items: center; }
.nav-link {
  font-family: var(--font-sans);
  font-size: 0.875rem; font-weight: 500;
  color: var(--text-secondary);
  padding: 0.4rem 0.75rem; border-radius: var(--radius-sm);
  transition: all var(--transition);
  text-decoration: none;
}
.nav-link:hover {
  color: var(--text-primary);
  background: var(--bg-primary);
  text-decoration: none;
}
.nav-link.active {
  color: var(--text-primary);
  background: var(--bg-primary);
}

.hamburger {
  display: none; flex-direction: column; gap: 5px;
  cursor: pointer; padding: 8px; z-index: 200;
}
.hamburger span {
  width: 24px; height: 2px;
  background: var(--text-primary); border-radius: 2px;
  transition: all var(--transition);
}
.hamburger.active span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.hamburger.active span:nth-child(2) { opacity: 0; }
.hamburger.active span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

/* ============ BREADCRUMB ============ */
.breadcrumb {
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  color: var(--text-tertiary);
  padding: var(--space-sm) 0;
  border-bottom: 1px solid var(--border);
  background: var(--bg-surface);
}
.breadcrumb a { color: var(--text-secondary); text-decoration: none; }
.breadcrumb a:hover { color: var(--accent); text-decoration: underline; }
.breadcrumb span { color: var(--text-tertiary); }

/* ============ BLOG LIST PAGE ============ */
.blog-list {
  padding: var(--space-3xl) 0;
}

.blog-list h1 {
  font-family: var(--font-sans);
  font-size: 2rem; font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--space-sm);
  letter-spacing: -0.02em;
}

.blog-list .section-desc {
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-2xl);
}

/* Blog Grid */
.blog-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-md);
}

/* Blog Card - Notion Style */
.blog-card {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  transition: all var(--transition);
  text-decoration: none;
  color: inherit;
  display: block;
}

.blog-card:hover {
  border-color: var(--border-hover);
  box-shadow: var(--shadow-card);
  transform: translateY(-2px);
  text-decoration: none;
}

.blog-card img {
  width: 100%;
  aspect-ratio: 16/9;
  object-fit: cover;
  border-radius: var(--radius-sm);
  margin-bottom: var(--space-sm);
  background: var(--bg-primary);
}

.blog-card h3 {
  font-family: var(--font-sans);
  font-size: 1rem; font-weight: 600;
  color: var(--text-primary);
  line-height: 1.5;
  margin-bottom: 0.5rem;
  letter-spacing: -0.01em;
}

.blog-card time {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  color: var(--text-tertiary);
  display: block;
  margin-bottom: 0.5rem;
}

.blog-card p {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.6;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* Pagination */
.pagination {
  display: flex; justify-content: center; gap: 0.5rem;
  margin: var(--space-2xl) 0;
}

.page-link {
  display: inline-flex; align-items: center; justify-content: center;
  min-width: 40px; height: 40px;
  padding: 0 0.75rem;
  font-family: var(--font-sans);
  font-size: 0.875rem; font-weight: 500;
  color: var(--text-secondary);
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  transition: all var(--transition);
}

.page-link:hover {
  color: var(--text-primary);
  border-color: var(--border-hover);
  background: var(--bg-primary);
  text-decoration: none;
}

.page-link.active {
  color: #fff;
  background: var(--accent);
  border-color: var(--accent);
}

/* ============ ARTICLE PAGE LAYOUT ============ */
.content-wrapper {
  display: grid;
  grid-template-columns: var(--content-width) var(--sidebar-width);
  gap: var(--space-2xl);
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-2xl) var(--space-md);
}

.main-content { min-width: 0; }

/* Article Styles */
article {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-2xl);
}

.blog-hero-image {
  width: 100%;
  aspect-ratio: 16/9;
  object-fit: cover;
  border-radius: var(--radius-md);
  margin-bottom: var(--space-lg);
  background: var(--bg-primary);
}

.article-content h1 {
  font-family: var(--font-sans);
  font-size: 1.75rem; font-weight: 700;
  color: var(--text-primary);
  line-height: 1.4;
  margin-bottom: var(--space-sm);
  letter-spacing: -0.02em;
}

.article-content time {
  color: var(--text-tertiary);
  font-size: 0.875rem;
  display: block;
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-md);
  border-bottom: 1px solid var(--border);
}

.article-content h2 {
  font-family: var(--font-sans);
  font-size: 1.375rem; font-weight: 600;
  color: var(--text-primary);
  margin: var(--space-2xl) 0 var(--space-md);
  letter-spacing: -0.01em;
}

.article-content h3 {
  font-family: var(--font-sans);
  font-size: 1.125rem; font-weight: 600;
  color: var(--text-primary);
  margin: var(--space-lg) 0 var(--space-sm);
}

.article-content p {
  font-size: 1rem;
  color: var(--text-primary);
  line-height: 1.75;
  margin-bottom: var(--space-md);
}

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

.article-content li {
  margin-bottom: 0.5rem;
  color: var(--text-primary);
}

.article-content a {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}

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

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

.article-content code {
  font-family: 'SF Mono', 'Fira Code', monospace;
  font-size: 0.875em;
  background: var(--bg-primary);
  padding: 0.15em 0.4em;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
}

.article-content pre {
  background: #1e1e1e;
  color: #d4d4d4;
  padding: var(--space-md);
  border-radius: var(--radius-md);
  overflow-x: auto;
  margin: var(--space-lg) 0;
  font-size: 0.875rem;
  line-height: 1.6;
  border: 1px solid var(--border);
}

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

/* Sidebar */
.sidebar {
  position: sticky;
  top: 80px;
  height: fit-content;
}

.sidebar-section {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  margin-bottom: var(--space-md);
}

.sidebar-section.sidebar-ad {
  padding: var(--space-sm);
  text-align: center;
}

.amazon-ad {
  min-height: 100px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: repeating-linear-gradient(
    45deg,
    var(--bg-secondary),
    var(--bg-secondary) 10px,
    rgba(0, 0, 0, 0.02) 10px,
    rgba(0, 0, 0, 0.02) 20px
  );
  border-radius: var(--radius-md);
  font-size: 0.8rem;
  color: var(--text-tertiary);
  font-weight: 500;
}

.sitenavi-block {
  text-align: center;
}

.sitenavi-block h3 {
  text-align: left;
}

.sitenavi-block a {
  display: block;
  margin: var(--space-xs) auto;
  border-radius: var(--radius-md);
  overflow: hidden;
}

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

.sidebar-section h3 {
  font-family: var(--font-sans);
  font-size: 0.75rem; font-weight: 600;
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-sm);
  padding-bottom: var(--space-xs);
  border-bottom: 1px solid var(--border);
}

.sidebar-nav { list-style: none; }
.sidebar-nav li { margin-bottom: 0.5rem; }
.sidebar-nav a {
  color: var(--text-secondary);
  font-size: 0.875rem;
  line-height: 1.5;
  display: block;
  padding: 0.25rem 0;
  text-decoration: none;
  transition: color var(--transition);
}
.sidebar-nav a:hover {
  color: var(--accent);
  text-decoration: none;
}

/* TOC List */
.toc-list {
  list-style: none;
}

.toc-list li {
  margin-bottom: 0.25rem;
}

.toc-list a {
  color: var(--text-secondary);
  font-size: 0.8125rem;
  line-height: 1.6;
  display: block;
  padding: 0.25rem 0.5rem;
  border-radius: var(--radius-sm);
  transition: all var(--transition);
}

.toc-list a:hover {
  color: var(--accent);
  background: var(--bg-primary);
}

/* Popular List (template) */
.popular-list li {
  margin-bottom: 0.5rem;
}

.popular-list a {
  font-size: 0.8125rem;
  line-height: 1.5;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.popular-list a::before {
  content: '';
  display: inline-block;
  width: 4px;
  height: 4px;
  background: var(--accent);
  border-radius: 50%;
  flex-shrink: 0;
}

/* Category Nav (template) */
.category-nav li {
  margin-bottom: 0.35rem;
}

.category-nav a {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.8125rem;
  padding: 0.35rem 0;
}

.nav-count {
  font-size: 0.6875rem;
  color: var(--text-tertiary);
  background: var(--bg-primary);
  padding: 0.1rem 0.4rem;
  border-radius: 10px;
  margin-left: 0.5rem;
}

/* Sidebar Search */
.sidebar-search-form {
  display: flex;
  gap: var(--space-xs);
}

.sidebar-search-input {
  flex: 1;
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  padding: 0.4rem 0.6rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-primary);
  color: var(--text-primary);
  transition: border-color var(--transition);
}

.sidebar-search-input:focus {
  outline: none;
  border-color: var(--accent);
}

.sidebar-search-input::placeholder {
  color: var(--text-tertiary);
}

.sidebar-search-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition);
  flex-shrink: 0;
}

.sidebar-search-btn:hover {
  background: var(--accent-hover);
}

/* Share Links */
.share-links {
  margin-top: var(--space-2xl);
  padding-top: var(--space-lg);
  border-top: 1px solid var(--border);
}

.share-links p {
  font-size: 0.875rem;
  color: var(--text-tertiary);
  margin-bottom: var(--space-sm);
}

.share-buttons { display: flex; gap: var(--space-sm); flex-wrap: wrap; }

.share-twitter, .share-facebook {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 0.5rem 1rem;
  border-radius: var(--radius-sm);
  color: white;
  text-decoration: none;
  font-size: 0.8125rem;
  font-weight: 500;
  transition: all var(--transition);
}

.share-twitter { background: #1da1f2; }
.share-twitter:hover { background: #1a91da; text-decoration: none; }

.share-facebook { background: #3b5998; }
.share-facebook:hover { background: #344e86; text-decoration: none; }

/* ============ FOOTER ============ */
.footer {
  background: var(--text-primary);
  color: rgba(255, 255, 255, 0.7);
  padding: var(--space-2xl) 0 var(--space-lg);
  margin-top: var(--space-3xl);
}

.footer-inner {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-lg);
}

.footer-brand .logo-main { color: #fff; font-size: 1.1rem; }
.footer-brand .logo-main span { color: var(--accent); }
.footer-brand p {
  font-size: 0.875rem; line-height: 1.6;
  margin-top: var(--space-sm); color: rgba(255, 255, 255, 0.5);
}

.footer h4 {
  font-family: var(--font-sans);
  font-size: 0.6875rem; font-weight: 600;
  letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--accent);
  margin-bottom: var(--space-sm);
}

.footer ul { list-style: none; }
.footer li { margin-bottom: 0.4rem; }
.footer a {
  color: rgba(255, 255, 255, 0.6);
  font-size: 0.875rem;
  transition: color var(--transition);
  text-decoration: none;
}
.footer a:hover { color: #fff; text-decoration: none; }

.footer-bottom {
  margin-top: var(--space-lg);
  padding-top: var(--space-md);
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  text-align: center;
  font-family: var(--font-sans);
  font-size: 0.75rem;
  color: rgba(255, 255, 255, 0.4);
}

.footer-legal { list-style: none !important; padding: 0 !important; display: flex; flex-wrap: wrap; gap: 1rem; justify-content: center; margin-bottom: 0.5rem; }
.footer-legal a { color: rgba(255, 255, 255, 0.6); font-size: 0.8125rem; }
.footer-legal a:hover { color: #fff; }

/* ============ BLOG LIST PAGE - 2 COLUMN LAYOUT ============ */
.blog-hero {
  padding: var(--space-3xl) 0 var(--space-xl);
  text-align: center;
}

.blog-hero h1 {
  font-family: var(--font-sans);
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--space-sm);
  letter-spacing: -0.03em;
}

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

/* 2 Column Layout */
.blog-layout {
  display: grid;
  grid-template-columns: 1fr var(--sidebar-width);
  gap: var(--space-2xl);
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-md) var(--space-3xl);
}

.blog-main {
  min-width: 0;
}

/* Sidebar Styles */
.blog-sidebar {
  position: sticky;
  top: 80px;
  height: fit-content;
}

.sidebar-section {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  margin-bottom: var(--space-md);
}

.sidebar-section h3 {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-sm);
  padding-bottom: var(--space-xs);
  border-bottom: 1px solid var(--border);
}

.sidebar-text {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
}

/* Search Form */
.search-form {
  display: flex;
  gap: var(--space-xs);
}

.search-input {
  flex: 1;
  font-family: var(--font-sans);
  font-size: 0.875rem;
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-primary);
  color: var(--text-primary);
  transition: border-color var(--transition);
}

.search-input:focus {
  outline: none;
  border-color: var(--accent);
}

.search-input::placeholder {
  color: var(--text-tertiary);
}

.search-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition);
}

.search-btn:hover {
  background: var(--accent-hover);
}

/* Popular Articles */
.popular-articles {
  list-style: none;
}

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

.popular-articles a {
  display: flex;
  gap: var(--space-sm);
  align-items: flex-start;
  text-decoration: none;
  color: inherit;
  padding: var(--space-xs);
  border-radius: var(--radius-sm);
  transition: background var(--transition);
}

.popular-articles a:hover {
  background: var(--bg-primary);
}

.popular-rank {
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 24px;
  height: 24px;
  background: var(--accent);
  color: #fff;
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
}

.popular-title {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.popular-articles a:hover .popular-title {
  color: var(--accent);
}

/* Category List */
.category-list {
  list-style: none;
}

.category-list li {
  margin-bottom: 0.25rem;
}

.category-list a {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.875rem;
  color: var(--text-secondary);
  padding: 0.5rem var(--space-xs);
  border-radius: var(--radius-sm);
  text-decoration: none;
  transition: all var(--transition);
}

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

.category-list .count {
  font-size: 0.75rem;
  color: var(--text-tertiary);
  background: var(--bg-primary);
  padding: 0.15rem 0.5rem;
  border-radius: 10px;
}

/* Subscribe Form */
.subscribe-form {
  display: flex;
  gap: var(--space-xs);
}

.subscribe-input {
  flex: 1;
  font-family: var(--font-sans);
  font-size: 0.875rem;
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-primary);
  color: var(--text-primary);
}

.subscribe-input:focus {
  outline: none;
  border-color: var(--accent);
}

.subscribe-btn {
  font-family: var(--font-sans);
  font-size: 0.875rem;
  font-weight: 500;
  padding: 0.5rem 1rem;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition);
}

.subscribe-btn:hover {
  background: var(--accent-hover);
}

/* ============ BACK TO TOP ============ */
.back-to-top {
  position: fixed; bottom: 2rem; right: 2rem;
  width: 44px; height: 44px;
  background: var(--accent);
  color: #fff;
  border: none; border-radius: 50%;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  opacity: 0; visibility: hidden;
  transition: all var(--transition);
  box-shadow: var(--shadow-md);
  z-index: 50;
}

.back-to-top.visible { opacity: 1; visibility: visible; }
.back-to-top:hover { background: var(--accent-hover); transform: translateY(-2px); }
.back-to-top svg { width: 20px; height: 20px; }

/* Scroll to top (alternative) */
.scroll-to-top {
  position: fixed; bottom: 2rem; right: 2rem;
  width: 44px; height: 44px;
  background: var(--accent);
  color: #fff;
  border: none; border-radius: 50%;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  opacity: 0; visibility: hidden;
  transition: all var(--transition);
  box-shadow: var(--shadow-md);
  z-index: 50;
  font-size: 1.25rem;
}

.scroll-to-top.visible { opacity: 1; visibility: visible; }
.scroll-to-top:hover { background: var(--accent-hover); transform: translateY(-2px); }

/* ============ RESPONSIVE ============ */
@media (max-width: 1024px) {
  .content-wrapper {
    grid-template-columns: 1fr;
  }
  .sidebar {
    position: static;
  }

  /* Blog list 2-column to 1-column */
  .blog-layout {
    grid-template-columns: 1fr;
  }
  .blog-sidebar {
    position: static;
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-md);
  }
  .sidebar-section {
    margin-bottom: 0;
  }
}

@media (max-width: 768px) {
  .blog-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-sm);
  }

  .blog-sidebar {
    grid-template-columns: 1fr;
  }

  .content-wrapper {
    padding: var(--space-md) var(--space-sm);
  }

  article {
    padding: var(--space-md);
  }

  .footer-inner {
    grid-template-columns: 1fr 1fr;
  }

  .container { padding: 0 var(--space-sm); }

  .nav {
    display: none;
    position: fixed; top: 56px; left: 0;
    width: 100%; background: var(--bg-surface);
    flex-direction: column;
    padding: var(--space-sm);
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow-lg);
  }

  .nav.open { display: flex; }
  .hamburger { display: flex; }

  .blog-hero h1 { font-size: 1.75rem; }
  .blog-hero-desc { font-size: 1rem; }
}

@media (max-width: 480px) {
  .blog-grid {
    grid-template-columns: 1fr;
  }

  .footer-inner {
    grid-template-columns: 1fr;
  }

  .article-content h1 { font-size: 1.375rem; }
}

/* ============ PRINT ============ */
@media print {
  .header, .footer, .sidebar, .back-to-top, .scroll-to-top, .reading-progress, .hamburger { display: none !important; }
  body { background: #fff; color: #000; font-size: 11pt; }
  .content-wrapper { display: block; max-width: 100%; }
  article { border: none; padding: 0; }
  a { color: #000; text-decoration: underline; }
}