/* ============================================
   xaan.cn - GEO Research Institute Styles
   专业智库风 · 低营销感 · B端知识库质感
   ============================================ */

:root {
  --primary: #1a365d;
  --primary-light: #2b6cb0;
  --accent: #2c5282;
  --accent-light: #4299e1;
  --text-dark: #1a202c;
  --text-body: #2d3748;
  --text-muted: #718096;
  --bg-white: #ffffff;
  --bg-light: #f7fafc;
  --bg-gray: #edf2f7;
  --border: #e2e8f0;
  --border-light: #f1f5f9;
  --success: #38a169;
  --warning: #d69e2e;
  --code-bg: #f6f8fa;
  --max-width: 1200px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
  --shadow-lg: 0 10px 30px rgba(0,0,0,0.1);
  --radius: 6px;
  --radius-lg: 10px;
}

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

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
               "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Helvetica,
               Arial, sans-serif;
  color: var(--text-body);
  background: var(--bg-white);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--primary-light);
  text-decoration: none;
  transition: color 0.2s;
}
a:hover { color: var(--primary); }

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

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

/* ========== Header / Nav ========== */
.site-header {
  background: #fff;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow-sm);
}
.nav-wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.nav-logo {
  display: flex;
  align-items: center;
  gap: 0;
  color: var(--primary);
  font-weight: 700;
  font-size: 20px;
  letter-spacing: 1px;
  text-decoration: none;
  line-height: 1.1;
}
.nav-logo .logo-sub {
  display: block;
  font-size: 11px;
  color: var(--accent-light);
  font-weight: 500;
  letter-spacing: 2px;
  margin-top: 4px;
  text-transform: uppercase;
}
.nav-menu {
  display: flex;
  list-style: none;
  gap: 4px;
}
.nav-menu li a {
  display: block;
  padding: 8px 14px;
  color: var(--text-body);
  font-size: 14px;
  border-radius: var(--radius);
  transition: all 0.2s;
}
.nav-menu li a:hover,
.nav-menu li a.active {
  background: var(--bg-light);
  color: var(--primary);
}
.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 24px;
  cursor: pointer;
  color: var(--text-dark);
}

/* ========== Hero / Page Banner ========== */
.hero {
  background: linear-gradient(135deg, #1a365d 0%, #2c5282 50%, #2b6cb0 100%);
  color: #fff;
  padding: 80px 0 70px;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0; bottom: 0;
  background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
}
.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
}
.hero-tag {
  display: inline-block;
  background: rgba(255,255,255,0.15);
  border: 1px solid rgba(255,255,255,0.25);
  padding: 4px 14px;
  border-radius: 20px;
  font-size: 13px;
  margin-bottom: 20px;
  letter-spacing: 1px;
}
.hero h1 {
  font-size: 36px;
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 16px;
}
.hero p {
  font-size: 17px;
  opacity: 0.9;
  line-height: 1.7;
}
.hero-single {
  padding: 60px 0 50px;
}
.hero-single h1 { font-size: 28px; margin-bottom: 10px; }
.hero-breadcrumb {
  font-size: 13px;
  opacity: 0.8;
}
.hero-breadcrumb a { color: rgba(255,255,255,0.9); }
.hero-breadcrumb a:hover { color: #fff; }

/* ========== Section Common ========== */
.section { padding: 60px 0; }
.section-alt { background: var(--bg-light); }
.section-header {
  text-align: center;
  margin-bottom: 40px;
}
.section-header h2 {
  font-size: 26px;
  color: var(--text-dark);
  margin-bottom: 10px;
  font-weight: 700;
}
.section-header p {
  color: var(--text-muted);
  font-size: 15px;
}

/* ========== Homepage Specific ========== */
.research-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}
.research-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: all 0.3s;
}
.research-card:hover {
  border-color: var(--accent-light);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}
.research-card .card-tag {
  display: inline-block;
  font-size: 12px;
  color: var(--accent-light);
  background: rgba(66,153,225,0.1);
  padding: 3px 10px;
  border-radius: 4px;
  margin-bottom: 14px;
}
.research-card h3 {
  font-size: 17px;
  color: var(--text-dark);
  margin-bottom: 10px;
  line-height: 1.5;
}
.research-card p {
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.6;
}

.category-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
.category-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 24px 22px;
  display: flex;
  align-items: center;
  gap: 18px;
  text-decoration: none;
  color: inherit;
  transition: all 0.25s ease;
  position: relative;
  overflow: hidden;
}
.category-card::after {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 4px; height: 100%;
  background: linear-gradient(180deg, var(--primary), var(--accent-light));
  opacity: 0;
  transition: opacity 0.25s ease;
}
.category-card:hover {
  border-color: var(--accent-light);
  box-shadow: 0 6px 20px rgba(43, 108, 176, 0.12);
  transform: translateY(-2px);
}
.category-card:hover::after { opacity: 1; }
.category-card:hover .cat-icon {
  background: linear-gradient(135deg, #e8f0fa, #d6e6f7);
  transform: scale(1.05);
}
.category-card:hover h4 { color: var(--primary); }
.category-card .cat-icon {
  flex-shrink: 0;
  width: 52px;
  height: 52px;
  background: #f0f4f8;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  transition: all 0.25s ease;
}
.category-card .cat-text {
  flex: 1;
  min-width: 0;
}
.category-card h4 {
  font-size: 15px;
  color: var(--text-dark);
  margin-bottom: 4px;
  font-weight: 600;
  transition: color 0.2s ease;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.category-card span {
  font-size: 12.5px;
  color: var(--text-muted);
  line-height: 1.5;
}

.featured-list {
  display: grid;
  gap: 12px;
}
.featured-item {
  display: flex;
  gap: 16px;
  padding: 20px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: all 0.2s;
}
.featured-item:hover {
  border-color: var(--accent-light);
  background: var(--bg-light);
}
.featured-item .fi-num {
  flex-shrink: 0;
  width: 32px;
  height: 32px;
  background: var(--primary);
  color: #fff;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
  font-weight: 600;
}
.featured-item h4 {
  font-size: 15px;
  color: var(--text-dark);
  margin-bottom: 4px;
}
.featured-item p {
  font-size: 13px;
  color: var(--text-muted);
}

/* ========== Breadcrumb ========== */
.breadcrumb {
  padding: 16px 0;
  background: var(--bg-light);
  border-bottom: 1px solid var(--border-light);
  font-size: 13px;
}
.breadcrumb ol {
  list-style: none;
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}
.breadcrumb li { color: var(--text-muted); }
.breadcrumb li:not(:last-child)::after {
  content: '›';
  margin-left: 6px;
  color: var(--text-muted);
}
.breadcrumb a { color: var(--text-muted); }
.breadcrumb a:hover { color: var(--primary); }

/* ========== Article ========== */
.article-main {
  display: grid;
  grid-template-columns: 1fr;
  gap: 40px;
}
.article-content {
  background: #fff;
  padding: 40px;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
}
.article-header {
  margin-bottom: 30px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--border);
}
.article-header h1 {
  font-size: 26px;
  color: var(--text-dark);
  line-height: 1.4;
  margin-bottom: 12px;
}
.article-meta {
  font-size: 13px;
  color: var(--text-muted);
  display: flex;
  gap: 16px;
}
.article-summary {
  background: var(--bg-light);
  border-left: 3px solid var(--primary);
  padding: 16px 20px;
  margin-bottom: 30px;
  font-size: 14px;
  color: var(--text-body);
  border-radius: 0 var(--radius) var(--radius) 0;
}
.article-body h2 {
  font-size: 20px;
  color: var(--text-dark);
  margin: 36px 0 16px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border-light);
}

/* ========== Checklist Article ========== */
.checklist-stats {
  display: flex;
  gap: 12px;
  margin: 24px 0 32px;
  flex-wrap: wrap;
}
.stat-card {
  flex: 1;
  min-width: 120px;
  background: #f8fafc;
  border: 1px solid #e2e8f0;
  border-radius: 8px;
  padding: 16px 12px;
  text-align: center;
  transition: all 0.25s;
}
.stat-card:hover {
  background: #fff;
  box-shadow: 0 4px 16px rgba(0,0,0,0.06);
  border-color: var(--primary-light);
}
.stat-num {
  display: block;
  font-size: 28px;
  font-weight: 700;
  color: var(--primary);
  line-height: 1.2;
}
.stat-num.stat-red { color: #dc2626; }
.stat-num.stat-orange { color: #ea580c; }
.stat-num.stat-blue { color: #0ea5e9; }
.stat-label {
  display: block;
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 4px;
}

.checklist-table {
  width: 100%;
  border-collapse: collapse;
  margin: 16px 0 28px;
  font-size: 14px;
  background: #fff;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 1px 3px rgba(0,0,0,0.06);
}
.checklist-table thead th {
  background: #1e3a8a;
  color: #fff;
  font-weight: 600;
  text-align: left;
  padding: 12px 14px;
  font-size: 13px;
  white-space: nowrap;
}
.checklist-table tbody td {
  padding: 12px 14px;
  border-bottom: 1px solid #eef2f7;
  vertical-align: top;
  line-height: 1.55;
}
.checklist-table tbody tr:nth-child(even) {
  background: #f8fafc;
}
.checklist-table tbody tr:hover {
  background: #eff6ff;
}
.checklist-table td:first-child {
  text-align: center;
  color: var(--text-muted);
  font-weight: 500;
}
.checklist-table td strong {
  color: var(--text-dark);
}
.checklist-table td:nth-child(4),
.checklist-table td:nth-child(5) {
  font-size: 13px;
  color: var(--text-secondary);
}
.checklist-table tbody tr:last-child td {
  border-bottom: none;
}

.tag-req, .tag-sug, .tag-if {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 4px;
  font-size: 12px;
  font-weight: 600;
  line-height: 1.2;
}
.tag-req {
  background: #fee2e2;
  color: #991b1b;
}
.tag-sug {
  background: #ffedd5;
  color: #9a3412;
}
.tag-if {
  background: #dbeafe;
  color: #1e40af;
}

@media (max-width: 720px) {
  .checklist-stats { gap: 8px; }
  .stat-card { min-width: 80px; padding: 12px 8px; }
  .stat-num { font-size: 22px; }
  .checklist-table { font-size: 13px; }
  .checklist-table thead th,
  .checklist-table tbody td { padding: 10px 10px; }
  .checklist-table td:nth-child(4),
  .checklist-table td:nth-child(5) { font-size: 12px; }
}
.article-body h3 {
  font-size: 17px;
  color: var(--text-dark);
  margin: 24px 0 12px;
}
.article-body p {
  margin-bottom: 16px;
  font-size: 15px;
  line-height: 1.85;
}
.article-body ul, .article-body ol {
  margin: 16px 0;
  padding-left: 24px;
}
.article-body li {
  margin-bottom: 8px;
  font-size: 15px;
  line-height: 1.75;
}
.article-body blockquote {
  background: var(--code-bg);
  border-left: 3px solid var(--accent-light);
  padding: 14px 20px;
  margin: 20px 0;
  border-radius: 0 var(--radius) var(--radius) 0;
  font-size: 14px;
  color: var(--text-body);
}
.article-body code {
  background: var(--code-bg);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 13px;
  font-family: "Fira Code", "Consolas", monospace;
  color: var(--primary);
}
.article-body table {
  width: 100%;
  border-collapse: collapse;
  margin: 20px 0;
  font-size: 14px;
}
.article-body th, .article-body td {
  padding: 12px 14px;
  border: 1px solid var(--border);
  text-align: left;
}
.article-body th {
  background: var(--bg-light);
  font-weight: 600;
  color: var(--text-dark);
}
.article-body tr:nth-child(even) td { background: var(--bg-light); }

/* FAQ styling */
.faq-list { margin: 20px 0; }
.faq-item {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 12px;
  overflow: hidden;
}
.faq-q {
  padding: 16px 20px;
  background: var(--bg-light);
  font-weight: 600;
  color: var(--text-dark);
  font-size: 15px;
  display: flex;
  align-items: center;
  gap: 10px;
}
.faq-q::before {
  content: 'Q';
  width: 24px;
  height: 24px;
  background: var(--primary);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  flex-shrink: 0;
}
.faq-a {
  padding: 16px 20px;
  font-size: 14px;
  line-height: 1.8;
  border-top: 1px solid var(--border-light);
}
.faq-a::before {
  content: 'A';
  display: inline-block;
  width: 24px;
  height: 24px;
  background: var(--success);
  color: #fff;
  border-radius: 50%;
  text-align: center;
  line-height: 24px;
  font-size: 12px;
  margin-right: 8px;
}

/* Soft CTA */
.soft-cta {
  background: linear-gradient(135deg, #f7fafc 0%, #edf2f7 100%);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  margin-top: 40px;
  text-align: center;
}
.soft-cta p {
  font-size: 14px;
  color: var(--text-muted);
  margin-bottom: 14px;
}
.soft-cta a {
  display: inline-block;
  padding: 10px 24px;
  background: var(--primary);
  color: #fff;
  border-radius: var(--radius);
  font-size: 14px;
  transition: background 0.2s;
}
.soft-cta a:hover { background: var(--primary-light); color: #fff; }

/* Sidebar for article */
.article-with-sidebar {
  display: grid;
  grid-template-columns: 1fr 280px;
  gap: 32px;
  align-items: start;
}
.sidebar-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 20px;
  margin-bottom: 20px;
}
.sidebar-card h4 {
  font-size: 15px;
  color: var(--text-dark);
  margin-bottom: 14px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border-light);
}
.sidebar-card ul { list-style: none; }
.sidebar-card li { margin-bottom: 10px; }
.sidebar-card li a {
  font-size: 13px;
  color: var(--text-body);
  display: block;
  padding: 6px 0;
  border-bottom: 1px solid var(--border-light);
}
.sidebar-card li a:hover { color: var(--primary); padding-left: 4px; }

/* ========== Category / List Page ========== */
.category-hero {
  background: linear-gradient(135deg, #2d3748 0%, #1a365d 100%);
  color: #fff;
  padding: 50px 0 40px;
}
.category-hero h1 {
  font-size: 28px;
  margin-bottom: 10px;
}
.category-hero p {
  font-size: 15px;
  opacity: 0.85;
}

.article-list {
  display: grid;
  gap: 16px;
}
.article-item {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px 28px;
  transition: all 0.2s;
}
.article-item:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow-sm);
}
.article-item .ai-tag {
  display: inline-block;
  font-size: 12px;
  color: var(--accent-light);
  background: rgba(66,153,225,0.08);
  padding: 2px 8px;
  border-radius: 3px;
  margin-bottom: 8px;
}
.article-item h3 {
  font-size: 17px;
  color: var(--text-dark);
  margin-bottom: 8px;
}
.article-item h3 a { color: var(--text-dark); }
.article-item h3 a:hover { color: var(--primary); }
.article-item p {
  font-size: 14px;
  color: var(--text-muted);
  margin-bottom: 8px;
}
.article-item .ai-date {
  font-size: 12px;
  color: var(--text-muted);
}

/* ========== Footer ========== */
.site-footer {
  background: #1a202c;
  color: #a0aec0;
  padding: 60px 0 0;
  margin-top: 60px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  padding-bottom: 40px;
  border-bottom: 1px solid rgba(255,255,255,0.08);
}
.footer-brand h3 {
  color: #fff;
  font-size: 18px;
  margin-bottom: 12px;
}
.footer-brand p {
  font-size: 13px;
  line-height: 1.8;
  margin-bottom: 14px;
}
.footer-grid h4 {
  color: #fff;
  font-size: 14px;
  margin-bottom: 16px;
}
.footer-grid ul { list-style: none; }
.footer-grid li { margin-bottom: 10px; }
.footer-grid li a {
  color: #a0aec0;
  font-size: 13px;
}
.footer-grid li a:hover { color: #fff; }

/* ========== Training Ad ========== */
.train-ad {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  background: linear-gradient(135deg, #1e3a8a 0%, #2563eb 50%, #1d4ed8 100%);
  border-radius: 12px;
  padding: 44px 48px;
  text-decoration: none;
  color: #fff;
  position: relative;
  overflow: hidden;
  border: 1px solid rgba(255,255,255,0.15);
  box-shadow: 0 8px 30px rgba(37, 99, 235, 0.25);
  transition: box-shadow 0.3s ease, transform 0.3s ease;
}
.train-ad::before {
  content: '';
  position: absolute;
  top: -60%; right: -5%;
  width: 400px; height: 400px;
  background: radial-gradient(circle, rgba(255,255,255,0.12) 0%, transparent 70%);
  pointer-events: none;
}
.train-ad::after {
  content: '';
  position: absolute;
  bottom: -60%; left: 10%;
  width: 300px; height: 300px;
  background: radial-gradient(circle, rgba(96,165,250,0.2) 0%, transparent 70%);
  pointer-events: none;
}
.train-ad:hover {
  box-shadow: 0 14px 44px rgba(37, 99, 235, 0.35);
  transform: translateY(-3px);
}
.train-ad-left {
  position: relative;
  z-index: 1;
  flex: 1;
}
.train-ad-tag {
  display: inline-block;
  background: #fbbf24;
  color: #78350f;
  padding: 4px 14px;
  border-radius: 4px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 1px;
  margin-bottom: 16px;
}
.train-ad h3 {
  font-size: 24px;
  font-weight: 700;
  margin-bottom: 10px;
  line-height: 1.4;
  letter-spacing: 0.5px;
}
.train-ad p {
  font-size: 14px;
  opacity: 0.9;
  line-height: 1.6;
  max-width: 560px;
}
.train-ad-right {
  position: relative;
  z-index: 1;
  flex-shrink: 0;
}
.train-ad-btn {
  display: inline-block;
  background: #fff;
  color: #1d4ed8;
  padding: 14px 32px;
  border-radius: 6px;
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.5px;
  transition: all 0.25s;
  white-space: nowrap;
}
.train-ad:hover .train-ad-btn {
  background: #fbbf24;
  color: #78350f;
  transform: scale(1.06);
  box-shadow: 0 4px 16px rgba(251, 191, 36, 0.4);
}

@media (max-width: 640px) {
  .train-ad {
    flex-direction: column;
    text-align: left;
    padding: 32px 24px;
  }
  .train-ad h3 { font-size: 19px; }
  .train-ad-right { width: 100%; }
  .train-ad-btn { display: block; text-align: center; }
}

.footer-bottom {
  padding: 24px 0;
  font-size: 12px;
  text-align: center;
  border-top: none;
}
.footer-bottom p { margin-bottom: 6px; }
.footer-bottom a { color: #a0aec0; }
.footer-bottom a:hover { color: #fff; }
.footer-matrix {
  display: flex;
  justify-content: center;
  gap: 20px;
  margin-bottom: 10px;
  flex-wrap: wrap;
}
.footer-matrix a {
  color: #a0aec0;
  font-size: 12px;
  padding: 4px 12px;
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: 20px;
}
.footer-matrix a:hover {
  color: #fff;
  border-color: rgba(255,255,255,0.3);
}

/* ========== Responsive ========== */
@media (max-width: 900px) {
  .article-with-sidebar {
    grid-template-columns: 1fr;
  }
  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 30px;
  }
  .category-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .hero h1 { font-size: 28px; }
}

@media (max-width: 768px) {
  .nav-menu {
    display: none;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: #fff;
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    padding: 16px;
    gap: 4px;
  }
  .nav-menu.show { display: flex; }
  .nav-menu li a { padding: 12px; }
  .nav-toggle { display: block; }
  .hero { padding: 50px 0 40px; }
  .hero h1 { font-size: 24px; }
  .article-content { padding: 24px; }
  .article-header h1 { font-size: 22px; }
  .section { padding: 40px 0; }
}

@media (max-width: 480px) {
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .category-grid {
    grid-template-columns: 1fr;
  }
  .container { padding: 0 16px; }
}