/* === Reset & Base === */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
  color: #1E293B; background: #FFFFFF; line-height: 1.6;
}
a { text-decoration: none; color: inherit; }
ul, ol { list-style: none; }
img { max-width: 100%; display: block; }

/* === Utility === */
.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }
.section { padding: 80px 0; }
.section-alt { background: #F8FAFC; }
.section-blue { background: #EFF6FF; }
.text-center { text-align: center; }
.text-secondary { color: #64748B; }

/* === Typography === */
h1 { font-size: 48px; font-weight: 700; line-height: 1.2; }
h2 { font-size: 36px; font-weight: 700; line-height: 1.3; margin-bottom: 16px; }
h3 { font-size: 24px; font-weight: 600; line-height: 1.4; }
h4 { font-size: 20px; font-weight: 600; }
p { font-size: 16px; line-height: 1.8; color: #475569; }
.subtitle { font-size: 18px; color: #64748B; margin-bottom: 48px; }

/* === Header === */
.header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: rgba(255,255,255,0.95); backdrop-filter: blur(10px);
  border-bottom: 1px solid #E2E8F0; height: 72px;
}
.header .container { display: flex; align-items: center; justify-content: space-between; height: 100%; }
.logo { font-size: 24px; font-weight: 700; color: #2563EB; display: flex; align-items: center; gap: 8px; }
.logo-icon { width: 36px; height: 36px; background: #2563EB; border-radius: 8px; display: flex; align-items: center; justify-content: center; color: #fff; font-size: 18px; font-weight: 700; }
.nav { display: flex; align-items: center; gap: 32px; }
.nav a { font-size: 15px; color: #475569; font-weight: 500; transition: color 0.2s; padding: 4px 0; border-bottom: 2px solid transparent; }
.nav a:hover { color: #2563EB; border-bottom-color: #2563EB; }
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 12px 28px; border-radius: 8px; font-size: 16px; font-weight: 600;
  transition: all 0.2s; cursor: pointer; border: none;
}
.btn-primary { background: #2563EB; color: #fff; }
.btn-primary:hover { background: #1D4ED8; transform: translateY(-1px); box-shadow: 0 4px 12px rgba(37,99,235,0.3); }
.btn-outline { background: transparent; color: #2563EB; border: 2px solid #2563EB; }
.btn-outline:hover { background: #EFF6FF; }
.btn-white { background: #fff; color: #2563EB; }
.btn-white:hover { background: #F8FAFC; transform: translateY(-1px); }
.btn-lg { padding: 16px 36px; font-size: 18px; border-radius: 10px; }
.btn-sm { padding: 8px 20px; font-size: 14px; }
.header .btn-primary { padding: 10px 24px; font-size: 14px; }
.mobile-menu-btn { display: none; background: none; border: none; font-size: 24px; cursor: pointer; color: #1E293B; }

/* === Hero === */
.hero {
  padding: 160px 0 100px; background: linear-gradient(135deg, #EFF6FF 0%, #DBEAFE 50%, #EFF6FF 100%);
  text-align: center; position: relative; overflow: hidden;
}
.hero::before {
  content: ''; position: absolute; top: -50%; right: -20%; width: 600px; height: 600px;
  background: radial-gradient(circle, rgba(37,99,235,0.08) 0%, transparent 70%); border-radius: 50%;
}
.hero::after {
  content: ''; position: absolute; bottom: -30%; left: -10%; width: 400px; height: 400px;
  background: radial-gradient(circle, rgba(37,99,235,0.06) 0%, transparent 70%); border-radius: 50%;
}
.hero .container { position: relative; z-index: 1; }
.hero h1 { font-size: 56px; margin-bottom: 20px; color: #0F172A; }
.hero h1 span { color: #2563EB; }
.hero .hero-sub { font-size: 20px; color: #2563EB; margin-bottom: 16px; font-weight: 500; letter-spacing: 2px; }
.hero .hero-desc { font-size: 18px; color: #64748B; max-width: 600px; margin: 0 auto 40px; }
.hero-btns { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }

/* === Stats === */
.stats { padding: 60px 0; background: #fff; }
.stats-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 32px; }
.stat-item { text-align: center; padding: 24px; }
.stat-number { font-size: 42px; font-weight: 700; color: #2563EB; margin-bottom: 8px; }
.stat-label { font-size: 16px; color: #64748B; }

/* === Features === */
.features-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }
.feature-card {
  background: #fff; border-radius: 16px; padding: 36px 28px; text-align: center;
  border: 1px solid #E2E8F0; transition: all 0.3s;
}
.feature-card:hover { transform: translateY(-4px); box-shadow: 0 12px 32px rgba(0,0,0,0.08); border-color: #BFDBFE; }
.feature-icon {
  width: 64px; height: 64px; border-radius: 16px; background: #EFF6FF;
  display: flex; align-items: center; justify-content: center;
  margin: 0 auto 20px; font-size: 28px;
}
.feature-card h3 { font-size: 20px; margin-bottom: 12px; }
.feature-card p { font-size: 15px; color: #64748B; }

/* === Nodes === */
.nodes-map {
  background: linear-gradient(135deg, #0F172A 0%, #1E293B 100%);
  border-radius: 20px; padding: 60px 40px; text-align: center; position: relative; overflow: hidden;
  margin-bottom: 48px;
}
.nodes-map h2 { color: #fff; }
.nodes-map p { color: #94A3B8; max-width: 600px; margin: 0 auto 40px; }
.nodes-dots { display: flex; justify-content: center; gap: 40px; flex-wrap: wrap; }
.node-dot {
  display: flex; flex-direction: column; align-items: center; gap: 8px;
}
.node-dot-circle {
  width: 16px; height: 16px; background: #2563EB; border-radius: 50%;
  box-shadow: 0 0 20px rgba(37,99,235,0.5);
  animation: pulse 2s infinite;
}
@keyframes pulse {
  0%, 100% { box-shadow: 0 0 20px rgba(37,99,235,0.5); }
  50% { box-shadow: 0 0 40px rgba(37,99,235,0.8); }
}
.node-dot span { color: #CBD5E1; font-size: 14px; font-weight: 500; }
.nodes-list { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 16px; }
.node-tag {
  background: #fff; border: 1px solid #E2E8F0; border-radius: 12px; padding: 20px;
  text-align: center; font-weight: 600; color: #1E293B; transition: all 0.2s;
}
.node-tag:hover { border-color: #2563EB; color: #2563EB; background: #EFF6FF; }
.node-flag { font-size: 32px; margin-bottom: 8px; }

/* === Pricing === */
.pricing-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.pricing-card {
  background: #fff; border-radius: 16px; padding: 40px 32px; text-align: center;
  border: 2px solid #E2E8F0; transition: all 0.3s; position: relative;
}
.pricing-card:hover { transform: translateY(-4px); box-shadow: 0 12px 32px rgba(0,0,0,0.08); }
.pricing-card.popular { border-color: #2563EB; }
.pricing-badge {
  position: absolute; top: -14px; left: 50%; transform: translateX(-50%);
  background: #2563EB; color: #fff; padding: 4px 20px; border-radius: 20px;
  font-size: 13px; font-weight: 600;
}
.pricing-name { font-size: 20px; font-weight: 600; color: #64748B; margin-bottom: 8px; }
.pricing-price { font-size: 48px; font-weight: 700; color: #0F172A; margin-bottom: 4px; }
.pricing-price span { font-size: 18px; color: #64748B; font-weight: 400; }
.pricing-period { font-size: 14px; color: #94A3B8; margin-bottom: 24px; }
.pricing-features { text-align: left; margin-bottom: 32px; }
.pricing-features li { padding: 8px 0; font-size: 15px; color: #475569; display: flex; align-items: center; gap: 8px; }
.pricing-features li::before { content: '\2713'; color: #10B981; font-weight: 700; }
.pricing-card .btn { width: 100%; }

/* === Testimonials === */
.testimonials-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.testimonial-card {
  background: #fff; border-radius: 16px; padding: 32px; border: 1px solid #E2E8F0;
}
.testimonial-stars { color: #F59E0B; font-size: 18px; margin-bottom: 16px; }
.testimonial-text { font-size: 15px; color: #475569; margin-bottom: 20px; font-style: italic; line-height: 1.8; }
.testimonial-author { display: flex; align-items: center; gap: 12px; }
.testimonial-avatar {
  width: 44px; height: 44px; border-radius: 50%; background: #EFF6FF;
  display: flex; align-items: center; justify-content: center;
  font-weight: 700; color: #2563EB; font-size: 18px;
}
.testimonial-name { font-weight: 600; font-size: 15px; }
.testimonial-source { font-size: 13px; color: #94A3B8; }

/* === FAQ === */
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item {
  background: #fff; border: 1px solid #E2E8F0; border-radius: 12px;
  margin-bottom: 16px; overflow: hidden;
}
.faq-item details { padding: 0; }
.faq-item summary {
  padding: 20px 24px; font-size: 17px; font-weight: 600; cursor: pointer;
  display: flex; align-items: center; justify-content: space-between;
  list-style: none; transition: background 0.2s;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after { content: '+'; font-size: 24px; color: #2563EB; font-weight: 300; transition: transform 0.2s; }
.faq-item details[open] summary::after { content: '\2212'; }
.faq-item summary:hover { background: #F8FAFC; }
.faq-answer { padding: 0 24px 24px; }
.faq-answer p { font-size: 15px; color: #475569; line-height: 1.8; margin-bottom: 8px; }
.faq-answer ol { padding-left: 20px; }
.faq-answer ol li { font-size: 15px; color: #475569; line-height: 1.8; margin-bottom: 6px; list-style: decimal; }

/* === CTA === */
.cta-section {
  padding: 80px 0; background: linear-gradient(135deg, #2563EB 0%, #1D4ED8 100%);
  text-align: center;
}
.cta-section h2 { color: #fff; margin-bottom: 16px; }
.cta-section p { color: rgba(255,255,255,0.85); font-size: 18px; margin-bottom: 36px; }

/* === Footer === */
.footer { background: #0F172A; color: #CBD5E1; padding: 60px 0 30px; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; margin-bottom: 40px; }
.footer-brand p { font-size: 14px; color: #94A3B8; margin-top: 12px; line-height: 1.8; }
.footer h4 { color: #fff; font-size: 16px; margin-bottom: 16px; }
.footer ul li { margin-bottom: 10px; }
.footer ul li a { font-size: 14px; color: #94A3B8; transition: color 0.2s; }
.footer ul li a:hover { color: #fff; }
.footer-bottom {
  border-top: 1px solid #1E293B; padding-top: 24px;
  display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 16px;
}
.footer-bottom p { font-size: 13px; color: #64748B; }
.footer-notice { font-size: 13px; color: #F59E0B; }

/* === Page Hero (sub pages) === */
.page-hero {
  padding: 140px 0 60px; background: linear-gradient(135deg, #EFF6FF 0%, #DBEAFE 100%);
  text-align: center;
}
.page-hero h1 { font-size: 42px; margin-bottom: 16px; }
.page-hero p { font-size: 18px; color: #64748B; max-width: 600px; margin: 0 auto; }

/* === Content blocks === */
.content-block { max-width: 800px; margin: 0 auto; }
.content-block h2 { margin-top: 40px; margin-bottom: 16px; font-size: 28px; }
.content-block h3 { margin-top: 32px; margin-bottom: 12px; }
.content-block p { margin-bottom: 16px; }
.content-block ul li, .content-block ol li { margin-bottom: 8px; padding-left: 8px; }

/* === Detail feature === */
.feature-detail { display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: center; margin-bottom: 80px; }
.feature-detail:nth-child(even) { direction: rtl; }
.feature-detail:nth-child(even) > * { direction: ltr; }
.feature-detail-img {
  background: linear-gradient(135deg, #EFF6FF, #DBEAFE);
  border-radius: 20px; padding: 60px; text-align: center; font-size: 80px;
}
.feature-detail-text h3 { font-size: 28px; margin-bottom: 16px; }
.feature-detail-text p { font-size: 16px; color: #475569; line-height: 1.8; margin-bottom: 16px; }

/* === Responsive === */
@media (max-width: 1024px) {
  .features-grid { grid-template-columns: repeat(2, 1fr); }
  .pricing-grid { grid-template-columns: repeat(2, 1fr); }
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
  .feature-detail { grid-template-columns: 1fr; gap: 32px; }
  .feature-detail:nth-child(even) { direction: ltr; }
}
@media (max-width: 768px) {
  h1 { font-size: 32px; }
  h2 { font-size: 28px; }
  .hero { padding: 120px 0 60px; }
  .hero h1 { font-size: 36px; }
  .section { padding: 48px 0; }
  .nav { display: none; }
  .mobile-menu-btn { display: block; }
  .features-grid { grid-template-columns: 1fr; }
  .pricing-grid { grid-template-columns: 1fr; max-width: 400px; margin: 0 auto; }
  .testimonials-grid { grid-template-columns: 1fr; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); gap: 16px; }
  .footer-grid { grid-template-columns: 1fr; }
  .footer-bottom { flex-direction: column; text-align: center; }
  .hero-btns { flex-direction: column; align-items: center; }
  .hero-btns .btn { width: 100%; max-width: 300px; }
  .nodes-dots { gap: 20px; }
}