/* ===== CSS Variables ===== */
:root {
  --primary: #1a8cff;
  --primary-dark: #0d6efd;
  --primary-light: #e8f4ff;
  --primary-bg: #f0f7ff;
  --text: #1a1a2e;
  --text-secondary: #6b7280;
  --text-muted: #9ca3af;
  --border: #e5e7eb;
  --bg: #ffffff;
  --bg-gray: #f8fafc;
  --footer-bg: #0f172a;
  --shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.08);
  --radius: 12px;
  --radius-lg: 16px;
  --font: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --container: 1200px;
  --header-h: 64px;
}

/* ===== Reset ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font);
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
ul { list-style: none; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0,0,0,0); }

.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 24px;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 500;
  border: 2px solid transparent;
  cursor: pointer;
  transition: all 0.2s;
  white-space: nowrap;
}
.btn-primary {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}
.btn-primary:hover { background: var(--primary-dark); border-color: var(--primary-dark); }
.btn-outline {
  background: #fff;
  color: var(--primary);
  border-color: var(--primary);
}
.btn-outline:hover { background: var(--primary-light); }
.btn-sm { padding: 6px 16px; font-size: 13px; }
.btn-block { width: 100%; }

/* ===== Header ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  height: var(--header-h);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-h);
  gap: 24px;
}
.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}
.logo-icon {
  width: 36px;
  height: 36px;
  background: linear-gradient(135deg, var(--primary), #4db8ff);
  color: #fff;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 16px;
}
.logo-text { display: flex; flex-direction: column; line-height: 1.2; }
.logo-text strong { font-size: 15px; font-weight: 600; }
.logo-text small { font-size: 10px; color: var(--text-muted); letter-spacing: 1px; }
.main-nav {
  display: flex;
  align-items: center;
  gap: 4px;
}
.nav-link {
  padding: 8px 14px;
  font-size: 14px;
  color: var(--text-secondary);
  border-radius: 6px;
  transition: color 0.2s;
  position: relative;
}
.nav-link:hover { color: var(--primary); }
.nav-link.active {
  color: var(--primary);
  font-weight: 500;
}
.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: 2px;
  left: 14px;
  right: 14px;
  height: 2px;
  background: var(--primary);
  border-radius: 1px;
}
.header-actions { display: flex; align-items: center; gap: 8px; }
.search-btn {
  width: 40px;
  height: 40px;
  border: none;
  background: transparent;
  color: var(--text-secondary);
  border-radius: 8px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
}
.search-btn:hover { background: var(--bg-gray); color: var(--primary); }
.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}
.menu-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text);
  border-radius: 1px;
}

/* ===== Hero ===== */
.hero {
  background: linear-gradient(135deg, #f0f7ff 0%, #e8f4ff 50%, #f5f9ff 100%);
  padding: 60px 0 40px;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image: radial-gradient(circle, rgba(26,140,255,0.08) 1px, transparent 1px);
  background-size: 24px 24px;
}
.hero-inner {
  display: grid;
  grid-template-columns: 1fr 380px;
  gap: 48px;
  align-items: center;
  position: relative;
}
.hero-title {
  font-size: 42px;
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 12px;
  color: var(--text);
}
.hero-subtitle {
  font-size: 18px;
  color: var(--primary);
  font-weight: 500;
  margin-bottom: 16px;
}
.hero-desc {
  font-size: 15px;
  color: var(--text-secondary);
  line-height: 1.8;
  margin-bottom: 28px;
  max-width: 520px;
}
.hero-actions {
  display: flex;
  gap: 12px;
  margin-bottom: 24px;
}
.hero-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.tag-pill {
  display: inline-block;
  padding: 4px 14px;
  background: rgba(255,255,255,0.8);
  border: 1px solid rgba(26,140,255,0.2);
  border-radius: 20px;
  font-size: 13px;
  color: var(--text-secondary);
}
.hero-visual {
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
}
.hero-bg-circle {
  position: absolute;
  width: 320px;
  height: 320px;
  background: linear-gradient(135deg, rgba(26,140,255,0.15), rgba(77,184,255,0.1));
  border-radius: 50%;
}
.hero-portrait {
  width: 280px;
  height: 340px;
  object-fit: cover;
  border-radius: var(--radius-lg);
  position: relative;
  z-index: 1;
  box-shadow: var(--shadow-lg);
}
.hero-signature {
  position: absolute;
  bottom: 20px;
  right: -10px;
  font-size: 28px;
  font-weight: 300;
  color: rgba(26,140,255,0.3);
  font-style: italic;
  z-index: 2;
  writing-mode: vertical-rl;
}

/* ===== Stats ===== */
.stats-bar {
  margin-top: -30px;
  position: relative;
  z-index: 2;
  padding-bottom: 40px;
}
.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}
.stat-card {
  background: #fff;
  border-radius: var(--radius);
  padding: 20px 24px;
  display: flex;
  align-items: center;
  gap: 16px;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
}
.stat-icon {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  flex-shrink: 0;
}
.stat-icon-note { background: #e0f7fa url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24' fill='none' stroke='%2300acc1' stroke-width='2'%3E%3Cpath d='M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8z'/%3E%3Cpolyline points='14 2 14 8 20 8'/%3E%3C/svg%3E") center/24px no-repeat; }
.stat-icon-review { background: #e3f2fd url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24' fill='none' stroke='%231a8cff' stroke-width='2'%3E%3Cpath d='M16 4h2a2 2 0 0 1 2 2v14a2 2 0 0 1-2 2H6a2 2 0 0 1-2-2V6a2 2 0 0 1 2-2h2'/%3E%3Crect x='8' y='2' width='8' height='4' rx='1'/%3E%3C/svg%3E") center/24px no-repeat; }
.stat-icon-topic { background: #e8f5e9 url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24' fill='none' stroke='%2343a047' stroke-width='2'%3E%3Cpath d='M12 2L2 7l10 5 10-5-10-5z'/%3E%3Cpath d='M2 17l10 5 10-5'/%3E%3Cpath d='M2 12l10 5 10-5'/%3E%3C/svg%3E") center/24px no-repeat; }
.stat-icon-update { background: #fff3e0 url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24' fill='none' stroke='%23ff9800' stroke-width='2'%3E%3Crect x='3' y='4' width='18' height='18' rx='2'/%3E%3Cline x1='16' y1='2' x2='16' y2='6'/%3E%3Cline x1='8' y1='2' x2='8' y2='6'/%3E%3Cline x1='3' y1='10' x2='21' y2='10'/%3E%3C/svg%3E") center/24px no-repeat; }
.stat-info strong {
  display: block;
  font-size: 22px;
  font-weight: 700;
  color: var(--text);
  line-height: 1.2;
}
.stat-info span {
  font-size: 13px;
  color: var(--text-secondary);
}

/* ===== Layout Grid ===== */
.main-content { padding: 20px 0 60px; }
.content-grid {
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: 32px;
  align-items: start;
}
.section-block { margin-bottom: 48px; }
.section-header { margin-bottom: 24px; }
.section-header h1,
.section-header h2 {
  font-size: 22px;
  font-weight: 700;
  margin-bottom: 4px;
}
.section-header p {
  font-size: 14px;
  color: var(--text-secondary);
}
.section-footer { text-align: center; margin-top: 24px; }

/* ===== Article Cards ===== */
.article-list { display: flex; flex-direction: column; gap: 20px; }
.article-card {
  display: flex;
  gap: 20px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  transition: box-shadow 0.2s;
}
.article-card:hover { box-shadow: var(--shadow); }
.article-thumb {
  flex-shrink: 0;
  width: 200px;
  height: 130px;
  border-radius: 8px;
  overflow: hidden;
}
.article-thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.3s;
}
.article-card:hover .article-thumb img { transform: scale(1.05); }
.article-body { flex: 1; min-width: 0; }
.article-tag {
  display: inline-block;
  padding: 2px 10px;
  border-radius: 4px;
  font-size: 12px;
  font-weight: 500;
  margin-bottom: 8px;
}
.tag-blue { background: #e3f2fd; color: #1565c0; }
.tag-green { background: #e8f5e9; color: #2e7d32; }
.tag-purple { background: #f3e5f5; color: #7b1fa2; }
.tag-orange { background: #fff3e0; color: #e65100; }
.article-body h3 {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 8px;
  line-height: 1.4;
}
.article-body h3 a:hover { color: var(--primary); }
.article-excerpt {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 10px;
  line-height: 1.6;
}
.article-meta {
  display: flex;
  gap: 16px;
  font-size: 13px;
  color: var(--text-muted);
}

/* ===== Topic Cards ===== */
.topic-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}
.topic-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  transition: box-shadow 0.2s, border-color 0.2s;
}
.topic-card:hover {
  box-shadow: var(--shadow);
  border-color: var(--primary);
}
.topic-icon {
  width: 44px;
  height: 44px;
  border-radius: 10px;
  margin-bottom: 16px;
}
.topic-icon-book { background: #e3f2fd url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='22' height='22' viewBox='0 0 24 24' fill='none' stroke='%231a8cff' stroke-width='2'%3E%3Cpath d='M4 19.5A2.5 2.5 0 0 1 6.5 17H20'/%3E%3Cpath d='M6.5 2H20v20H6.5A2.5 2.5 0 0 1 4 19.5v-15A2.5 2.5 0 0 1 6.5 2z'/%3E%3C/svg%3E") center/22px no-repeat; }
.topic-icon-ai { background: #f3e5f5 url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='22' height='22' viewBox='0 0 24 24' fill='none' stroke='%237b1fa2' stroke-width='2'%3E%3Cpath d='M12 2a4 4 0 0 1 4 4v1h1a3 3 0 0 1 0 6h-1v1a4 4 0 0 1-8 0v-1H7a3 3 0 0 1 0-6h1V6a4 4 0 0 1 4-4z'/%3E%3C/svg%3E") center/22px no-repeat; }
.topic-icon-platform { background: #e8f5e9 url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='22' height='22' viewBox='0 0 24 24' fill='none' stroke='%2343a047' stroke-width='2'%3E%3Crect x='2' y='3' width='20' height='14' rx='2'/%3E%3Cline x1='8' y1='21' x2='16' y2='21'/%3E%3Cline x1='12' y1='17' x2='12' y2='21'/%3E%3C/svg%3E") center/22px no-repeat; }
.topic-card h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 8px;
}
.topic-card p {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 16px;
}
.topic-link {
  font-size: 13px;
  color: var(--primary);
  font-weight: 500;
}
.topic-link:hover { text-decoration: underline; }

/* ===== Timeline ===== */
.timeline {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
  position: relative;
}
.timeline-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: 0 12px;
}
.timeline-marker {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin-bottom: 12px;
  position: relative;
  width: 100%;
}
.timeline-dot {
  width: 14px;
  height: 14px;
  background: var(--primary);
  border: 3px solid var(--primary-light);
  border-radius: 50%;
  z-index: 1;
}
.timeline-line {
  position: absolute;
  top: 7px;
  left: 50%;
  width: 100%;
  height: 2px;
  background: var(--border);
}
.timeline-content time {
  font-size: 13px;
  color: var(--primary);
  font-weight: 600;
  display: block;
  margin-bottom: 4px;
}
.timeline-content h4 {
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 4px;
}
.timeline-content p {
  font-size: 12px;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* ===== Sidebar ===== */
.sidebar { display: flex; flex-direction: column; gap: 20px; }
.widget {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
}
.widget-title {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
}
.widget-desc {
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 12px;
}
.author-widget { text-align: center; }
.author-avatar {
  width: 80px;
  height: 80px;
  border-radius: 50%;
  overflow: hidden;
  margin: 0 auto 12px;
  border: 3px solid var(--primary-light);
}
.author-avatar img { width: 100%; height: 100%; object-fit: cover; }
.author-name { font-size: 18px; font-weight: 600; margin-bottom: 8px; }
.author-bio {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 16px;
}
.author-actions { display: flex; gap: 8px; justify-content: center; }
.category-list li { border-bottom: 1px solid var(--border); }
.category-list li:last-child { border-bottom: none; }
.category-list a {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 0;
  font-size: 14px;
  transition: color 0.2s;
}
.category-list a:hover { color: var(--primary); }
.cat-count {
  background: var(--bg-gray);
  padding: 2px 8px;
  border-radius: 10px;
  font-size: 12px;
  color: var(--text-muted);
}
.learning-path { display: flex; flex-direction: column; gap: 0; }
.path-item {
  display: flex;
  gap: 12px;
  padding: 10px 0;
  position: relative;
}
.path-item:not(:last-child)::after {
  content: '';
  position: absolute;
  left: 11px;
  top: 32px;
  width: 2px;
  height: calc(100% - 12px);
  background: var(--border);
}
.path-dot {
  width: 24px;
  height: 24px;
  background: var(--primary-light);
  color: var(--primary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  font-weight: 600;
  flex-shrink: 0;
}
.path-content { display: flex; flex-direction: column; }
.path-content strong { font-size: 14px; font-weight: 500; }
.path-content span { font-size: 12px; color: var(--text-muted); }
.recent-list li {
  padding: 8px 0;
  border-bottom: 1px solid var(--border);
}
.recent-list li:last-child { border-bottom: none; }
.recent-list a {
  font-size: 14px;
  display: block;
  margin-bottom: 2px;
  line-height: 1.4;
}
.recent-list a:hover { color: var(--primary); }
.recent-list time {
  font-size: 12px;
  color: var(--text-muted);
}
.subscribe-form input {
  width: 100%;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
  margin-bottom: 10px;
  outline: none;
  font-family: var(--font);
}
.subscribe-form input:focus { border-color: var(--primary); }

/* ===== Post Page ===== */
.post-page, .page-content, .archive-page { padding: 40px 0 60px; }
.post-header { margin-bottom: 32px; }
.post-title {
  font-size: 32px;
  font-weight: 700;
  line-height: 1.3;
  margin: 12px 0;
}
.post-meta {
  display: flex;
  gap: 16px;
  font-size: 14px;
  color: var(--text-muted);
}
.post-content {
  font-size: 16px;
  line-height: 1.8;
  color: var(--text);
}
.post-content h2 { font-size: 24px; margin: 32px 0 16px; }
.post-content h3 { font-size: 20px; margin: 24px 0 12px; }
.post-content p { margin-bottom: 16px; }
.post-content ul, .post-content ol { margin: 0 0 16px 24px; }
.post-content li { margin-bottom: 6px; }
.post-content blockquote {
  border-left: 4px solid var(--primary);
  padding: 12px 20px;
  margin: 16px 0;
  background: var(--bg-gray);
  color: var(--text-secondary);
}
.post-content code {
  background: var(--bg-gray);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 14px;
}
.post-content pre {
  background: #1e293b;
  color: #e2e8f0;
  padding: 16px;
  border-radius: 8px;
  overflow-x: auto;
  margin: 16px 0;
}
.post-content pre code { background: none; padding: 0; color: inherit; }
.post-tags { margin-top: 32px; display: flex; gap: 8px; flex-wrap: wrap; }

/* ===== Pagination ===== */
.pagination {
  display: flex;
  justify-content: center;
  gap: 8px;
  margin-top: 32px;
}
.pagination a, .pagination span {
  padding: 8px 16px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 14px;
}
.pagination a:hover { border-color: var(--primary); color: var(--primary); }
.pagination .current {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

/* ===== Footer ===== */
.site-footer {
  background: var(--footer-bg);
  color: #cbd5e1;
  padding-top: 48px;
}
.footer-top {
  display: grid;
  grid-template-columns: 1.2fr 1fr 1fr;
  gap: 40px;
  padding-bottom: 40px;
}
.footer-logo .logo-text strong { color: #fff; }
.footer-logo .logo-text small { color: #64748b; }
.footer-slogan {
  margin-top: 12px;
  font-size: 14px;
  color: #94a3b8;
}
.footer-contact h4,
.footer-social h4 {
  color: #fff;
  font-size: 15px;
  margin-bottom: 16px;
}
.footer-contact li {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 14px;
  margin-bottom: 10px;
  color: #94a3b8;
}
.footer-contact svg { flex-shrink: 0; color: var(--primary); }
.social-icons { display: flex; gap: 12px; }
.social-icon {
  width: 40px;
  height: 40px;
  border-radius: 8px;
  background: rgba(255,255,255,0.08);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s;
}
.social-icon:hover { background: var(--primary); }
.social-wechat { background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='20' height='20' viewBox='0 0 24 24' fill='%2394a3b8'%3E%3Cpath d='M8.5 13.5c-.83 0-1.5-.67-1.5-1.5s.67-1.5 1.5-1.5 1.5.67 1.5 1.5-.67 1.5-1.5 1.5zm7 0c-.83 0-1.5-.67-1.5-1.5s.67-1.5 1.5-1.5 1.5.67 1.5 1.5-.67 1.5-1.5 1.5z'/%3E%3Cpath d='M12 2C6.48 2 2 5.82 2 10.5c0 2.67 1.47 5.06 3.78 6.68-.1.92-.58 3.22-.66 3.72 0 0 .01.08.05.1.06.04.14.02.2-.02.47-.32 2.78-1.83 3.27-2.17.77.11 1.56.17 2.36.17 5.52 0 10-3.82 10-8.5S17.52 2 12 2z'/%3E%3C/svg%3E"); background-repeat: no-repeat; background-position: center; }
.social-xiaohongshu { background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='20' height='20' viewBox='0 0 24 24' fill='%23ff2442'%3E%3Crect x='3' y='3' width='18' height='18' rx='4'/%3E%3C/svg%3E"); background-repeat: no-repeat; background-position: center; }
.social-juejin { background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='20' height='20' viewBox='0 0 24 24' fill='%23007fff'%3E%3Cpath d='M12 2L2 7l10 5 10-5-10-5z'/%3E%3C/svg%3E"); background-repeat: no-repeat; background-position: center; }
.social-zhihu { background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='20' height='20' viewBox='0 0 24 24' fill='%230066ff'%3E%3Ccircle cx='12' cy='12' r='10'/%3E%3C/svg%3E"); background-repeat: no-repeat; background-position: center; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.08);
  padding: 20px 0;
}
.footer-bottom-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 13px;
  color: #64748b;
}
.footer-links { display: flex; gap: 20px; align-items: center; }
.footer-links a:hover { color: #fff; }

/* ===== Responsive ===== */
@media (max-width: 1024px) {
  .hero-inner { grid-template-columns: 1fr; text-align: center; }
  .hero-desc { margin-left: auto; margin-right: auto; }
  .hero-actions { justify-content: center; }
  .hero-tags { justify-content: center; }
  .hero-visual { margin-top: 20px; }
  .hero-signature { display: none; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .content-grid { grid-template-columns: 1fr; }
  .topic-grid { grid-template-columns: 1fr; }
  .timeline { grid-template-columns: repeat(2, 1fr); gap: 24px; }
  .timeline-line { display: none; }
  .footer-top { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
  .main-nav {
    display: none;
    position: absolute;
    top: var(--header-h);
    left: 0;
    right: 0;
    background: #fff;
    flex-direction: column;
    padding: 16px;
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow);
  }
  .main-nav.open { display: flex; }
  .menu-toggle { display: flex; }
  .hero-title { font-size: 28px; }
  .hero-portrait { width: 220px; height: 270px; }
  .stats-grid { grid-template-columns: 1fr 1fr; }
  .article-card { flex-direction: column; }
  .article-thumb { width: 100%; height: 180px; }
  .timeline { grid-template-columns: 1fr; }
  .footer-bottom-inner { flex-direction: column; gap: 8px; text-align: center; }
}