:root {
  --primary: #2563eb;
  --primary-dark: #1e40af;
  --accent: #0891b2;
  --bg-light: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-card: #ffffff;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;
  --border: #e2e8f0;
  --border-light: #f1f5f9;
  --gradient-1: linear-gradient(135deg, #2563eb 0%, #0891b2 100%);
  --gradient-2: linear-gradient(135deg, #f8fafc 0%, #ffffff 100%);
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -1px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -2px rgba(0, 0, 0, 0.04);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  background: var(--bg-light);
  color: var(--text-primary);
  line-height: 1.7;
  overflow-x: hidden;
}

/* Header */
.site-header {
  position: fixed;
  top: 0;
  width: 100%;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  z-index: 1000;
  padding: 0.8rem 0;
  box-shadow: var(--shadow-sm);
}

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

.logo {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
}

.logo-icon {
  height: 36px;
  width: auto;
  border-radius: 8px;
  object-fit: contain;
}

.logo-text {
  font-size: 1.3rem;
  font-weight: 700;
  background: var(--gradient-1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.logo-sub { font-weight: 300; opacity: 0.7; }

nav a {
  color: var(--text-secondary);
  text-decoration: none;
  margin-left: 2rem;
  font-size: 0.9rem;
  transition: color 0.3s;
}

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

/* Hero */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 6rem 2rem 4rem;
  position: relative;
  overflow: hidden;
  background: var(--bg-secondary);
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(ellipse at center, rgba(37, 99, 235, 0.05) 0%, transparent 70%);
  animation: pulse 8s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { transform: scale(1); opacity: 0.5; }
  50% { transform: scale(1.1); opacity: 1; }
}

.hero-content { position: relative; z-index: 1; max-width: 800px; }

.hero h1 {
  font-size: 3.5rem;
  font-weight: 800;
  margin-bottom: 1.5rem;
  background: var(--gradient-1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  line-height: 1.2;
}

.hero .subtitle {
  font-size: 1.3rem;
  color: var(--text-secondary);
  margin-bottom: 2.5rem;
  line-height: 1.8;
}

.hero .cta-group { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; }

.btn {
  display: inline-block;
  padding: 0.9rem 2rem;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  text-decoration: none;
  transition: all 0.3s;
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: var(--gradient-1);
  color: white;
  box-shadow: var(--shadow-md);
}

.btn-primary:hover { transform: translateY(-2px); box-shadow: var(--shadow-lg); }

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

.btn-outline:hover { border-color: var(--primary); color: var(--primary); }

/* Stats */
.stats-bar {
  background: var(--bg-light);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  padding: 3rem 2rem;
}

.stats-grid {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 2rem;
  text-align: center;
}

.stat-item .stat-number {
  font-size: 2.5rem;
  font-weight: 800;
  background: var(--gradient-1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.stat-item .stat-label {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-top: 0.5rem;
}

/* Sections */
.section {
  max-width: 1200px;
  margin: 0 auto;
  padding: 5rem 2rem;
}

.section-header {
  text-align: center;
  margin-bottom: 4rem;
}

.section-header h2 {
  font-size: 2.2rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: var(--text-primary);
}

.section-header p {
  color: var(--text-secondary);
  font-size: 1.1rem;
  max-width: 600px;
  margin: 0 auto;
}

/* Feature Cards */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 2rem;
  transition: all 0.3s;
  box-shadow: var(--shadow-sm);
}

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

.feature-icon {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  background: var(--gradient-1);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 1.2rem;
}

.feature-card h3 { 
  font-size: 1.2rem; 
  margin-bottom: 0.8rem; 
  color: var(--text-primary);
}

.feature-card p { 
  color: var(--text-secondary); 
  font-size: 0.95rem; 
  line-height: 1.7; 
}

/* Chips / Tags */
.chip-group { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-top: 1rem; }
.chip {
  background: rgba(8, 145, 178, 0.08);
  border: 1px solid rgba(8, 145, 178, 0.2);
  color: var(--accent);
  padding: 0.3rem 0.8rem;
  border-radius: 20px;
  font-size: 0.8rem;
}

/* Footer */
.site-footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border);
  padding: 3rem 2rem;
  text-align: center;
}

.footer-inner { max-width: 1200px; margin: 0 auto; }
.footer-links { margin-bottom: 1.5rem; }
.footer-links a { 
  color: var(--text-secondary); 
  text-decoration: none; 
  margin: 0 1rem; 
  font-size: 0.9rem; 
  transition: color 0.2s;
}
.footer-links a:hover { color: var(--primary); }
.footer-copy { color: var(--text-muted); font-size: 0.8rem; }

/* Page layout */
.page-hero {
  padding: 8rem 2rem 4rem;
  text-align: center;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border);
}

.page-hero h1 { 
  font-size: 2.5rem; 
  font-weight: 700; 
  margin-bottom: 1rem; 
  color: var(--text-primary);
}

.page-hero p { 
  color: var(--text-secondary); 
  font-size: 1.1rem; 
  max-width: 600px; 
  margin: 0 auto; 
}

.page-content { max-width: 900px; margin: 0 auto; padding: 4rem 2rem; }
.page-content h2 { 
  font-size: 1.8rem; 
  margin: 2.5rem 0 1rem; 
  color: var(--primary); 
}
.page-content h3 { 
  font-size: 1.3rem; 
  margin: 2rem 0 0.8rem; 
  color: var(--text-primary);
}
.page-content p { 
  color: var(--text-secondary); 
  margin-bottom: 1.2rem; 
  line-height: 1.8; 
}
.page-content ul, .page-content ol { 
  color: var(--text-secondary); 
  margin: 1rem 0 1.5rem 1.5rem; 
}
.page-content li { margin-bottom: 0.5rem; }

/* Responsive */
@media (max-width: 768px) {
  .hero h1 { font-size: 2.2rem; }
  .features-grid { grid-template-columns: 1fr; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  nav a { margin-left: 1rem; font-size: 0.8rem; }
  .header-inner { padding: 0 1rem; }
  .logo-icon { height: 30px; }
  .logo-text { font-size: 1.1rem; }
}

/* ========== 咨询问答库 ========== */
.qa-filters {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}
.qa-filter {
  padding: 0.4rem 1rem;
  border: 1px solid var(--border);
  border-radius: 20px;
  background: var(--bg-light);
  color: var(--text-secondary);
  cursor: pointer;
  font-size: 0.85rem;
  transition: all 0.2s;
}
.qa-filter:hover { 
  border-color: var(--primary); 
  color: var(--primary); 
}
.qa-filter.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}

.qa-search {
  position: relative;
  margin-bottom: 2rem;
}
.qa-search input {
  width: 100%;
  padding: 0.8rem 1rem 0.8rem 2.8rem;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--bg-light);
  color: var(--text-primary);
  font-size: 0.95rem;
  transition: border-color 0.2s;
}
.qa-search input:focus {
  outline: none;
  border-color: var(--primary);
}
.qa-search-icon {
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  font-size: 1rem;
  color: var(--text-muted);
}

.qa-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.qa-card {
  padding: 1.2rem 1.5rem;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--bg-light);
  transition: all 0.2s;
  box-shadow: var(--shadow-sm);
}
.qa-card:hover {
  border-color: var(--primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}
.qa-card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.6rem;
}
.qa-category-tag {
  display: inline-block;
  padding: 0.2rem 0.6rem;
  border-radius: 6px;
  background: rgba(37, 99, 235, 0.08);
  color: var(--primary);
  font-size: 0.75rem;
  font-weight: 600;
}
.qa-date {
  font-size: 0.8rem;
  color: var(--text-muted);
}
.qa-title {
  font-size: 1.1rem;
  margin-bottom: 0.5rem;
}
.qa-title a {
  color: var(--text-primary);
  text-decoration: none;
  transition: color 0.2s;
}
.qa-title a:hover { color: var(--primary); }
.qa-summary {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 0.8rem;
}
.qa-tags {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}
.qa-tag {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.qa-empty {
  text-align: center;
  padding: 4rem 0;
  color: var(--text-muted);
}
.qa-empty a { color: var(--primary); }

/* 咨询详情页 */
.qa-detail { padding: 2rem 0; }
.qa-breadcrumb {
  margin-bottom: 1.5rem;
}
.qa-breadcrumb a {
  color: var(--primary);
  text-decoration: none;
  font-size: 0.9rem;
}
.qa-detail-card {
  padding: 2rem;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--bg-light);
  margin-bottom: 2rem;
  box-shadow: var(--shadow-sm);
}
.qa-detail-meta {
  display: flex;
  gap: 1rem;
  align-items: center;
  margin-bottom: 1rem;
}
.qa-detail-card h1 {
  font-size: 1.6rem;
  margin-bottom: 0.8rem;
  color: var(--text-primary);
}
.qa-content {
  line-height: 1.8;
  color: var(--text-primary);
}
.qa-content h2 {
  font-size: 1.2rem;
  color: var(--primary);
  margin: 1.5rem 0 0.8rem;
}
.qa-content h3 {
  font-size: 1.05rem;
  margin: 1.2rem 0 0.6rem;
  color: var(--text-primary);
}
.qa-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
}
.qa-content th, .qa-content td {
  padding: 0.6rem 0.8rem;
  border: 1px solid var(--border);
  font-size: 0.9rem;
}
.qa-content th {
  background: var(--bg-secondary);
  font-weight: 600;
  color: var(--text-primary);
}
.qa-content blockquote {
  margin: 1.5rem 0;
  padding: 1rem 1.2rem;
  border-left: 3px solid var(--primary);
  background: var(--bg-secondary);
  border-radius: 0 8px 8px 0;
}
.qa-content blockquote a { color: var(--primary); font-weight: 600; }

.qa-cta {
  text-align: center;
  padding: 2rem;
  border: 1px dashed var(--border);
  border-radius: 12px;
  background: var(--bg-secondary);
}
.qa-cta h3 { 
  margin-bottom: 0.5rem; 
  color: var(--text-primary);
}
.qa-cta p { 
  color: var(--text-secondary); 
  margin-bottom: 1rem; 
}

@media (max-width: 768px) {
  .qa-detail-card { padding: 1.2rem; }
  .qa-detail-card h1 { font-size: 1.3rem; }
}

/* ========== Mobile Menu Toggle ========== */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.mobile-menu-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: all 0.3s;
}
.mobile-menu-toggle.active span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.mobile-menu-toggle.active span:nth-child(2) { opacity: 0; }
.mobile-menu-toggle.active span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

/* ========== Footer Grid ========== */
.footer-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 2rem;
  text-align: left;
  margin-bottom: 2rem;
}
.footer-col {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}
.footer-col h4 {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}
.footer-col a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.85rem;
  transition: color 0.2s;
}
.footer-col a:hover { color: var(--primary); }

/* ========== Enhanced Responsive ========== */
@media (max-width: 768px) {
  .mobile-menu-toggle { display: flex; }
  nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
    padding: 1rem 2rem;
    flex-direction: column;
    box-shadow: var(--shadow-lg);
  }
  nav.nav-open { display: flex; }
  nav a {
    margin-left: 0;
    padding: 0.6rem 0;
    font-size: 0.95rem;
    border-bottom: 1px solid var(--border-light);
  }
  nav a:last-child { border-bottom: none; }
  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
  }
}

@media (max-width: 480px) {
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .hero h1 { font-size: 1.8rem; }
  .hero .subtitle { font-size: 1rem; }
}