/* === 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", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  color: #1E293B; background: #FFFFFF; line-height: 1.6;
}
a { text-decoration: none; color: inherit; transition: color .2s; }
ul, ol { list-style: none; }
img { max-width: 100%; height: auto; display: block; }

/* === Container === */
.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }

/* === Navigation === */
.site-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: #1E293B; box-shadow: 0 2px 12px rgba(0,0,0,.15);
}
.nav-inner {
  max-width: 1200px; margin: 0 auto; padding: 0 20px;
  display: flex; align-items: center; justify-content: space-between; height: 64px;
}
.nav-logo { display: flex; align-items: center; gap: 10px; }
.nav-logo-icon {
  width: 36px; height: 36px; background: #2563EB; border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  color: #fff; font-weight: 700; font-size: 18px;
}
.nav-logo-text { color: #fff; font-size: 20px; font-weight: 700; letter-spacing: 1px; }
.nav-links { display: flex; align-items: center; gap: 32px; }
.nav-links a {
  color: rgba(255,255,255,.85); font-size: 15px; font-weight: 500;
  padding: 6px 0; position: relative; transition: color .2s;
}
.nav-links a:hover, .nav-links a.active { color: #fff; }
.nav-links a::after {
  content: ''; position: absolute; bottom: 0; left: 0; right: 0;
  height: 2px; background: #2563EB; transform: scaleX(0); transition: transform .2s;
}
.nav-links a:hover::after, .nav-links a.active::after { transform: scaleX(1); }
.nav-cta {
  display: inline-block; background: #2563EB; color: #fff !important;
  padding: 8px 22px; border-radius: 6px; font-weight: 600; font-size: 14px;
  transition: background .2s, transform .15s;
}
.nav-cta:hover { background: #1d4ed8; transform: translateY(-1px); }
.nav-cta::after { display: none !important; }

/* Mobile nav toggle */
.nav-toggle { display: none; flex-direction: column; gap: 5px; cursor: pointer; padding: 8px; }
.nav-toggle span { width: 24px; height: 2px; background: #fff; border-radius: 2px; }

/* === Hero === */
.hero {
  padding: 140px 0 80px; background: linear-gradient(135deg, #1E293B 0%, #0f172a 50%, #1e3a5f 100%);
  color: #fff; text-align: center; position: relative; overflow: hidden;
}
.hero::before {
  content: ''; position: absolute; top: -50%; left: -50%; width: 200%; height: 200%;
  background: radial-gradient(circle at 30% 40%, rgba(37,99,235,.15) 0%, transparent 50%),
              radial-gradient(circle at 70% 60%, rgba(16,185,129,.1) 0%, transparent 50%);
}
.hero-content { position: relative; z-index: 1; }
.hero h1 { font-size: 48px; font-weight: 800; margin-bottom: 16px; line-height: 1.2; }
.hero h1 span { color: #2563EB; }
.hero .subtitle {
  font-size: 20px; color: rgba(255,255,255,.8); max-width: 640px; margin: 0 auto 12px; line-height: 1.6;
}
.hero .trust-badge {
  font-size: 14px; color: rgba(255,255,255,.6); margin-bottom: 36px;
}
.hero-btns { display: flex; justify-content: center; gap: 16px; flex-wrap: wrap; margin-bottom: 32px; }
.btn-primary {
  display: inline-block; background: #2563EB; color: #fff;
  padding: 14px 40px; border-radius: 8px; font-size: 18px; font-weight: 700;
  transition: background .2s, transform .15s, box-shadow .2s;
  box-shadow: 0 4px 14px rgba(37,99,235,.4);
}
.btn-primary:hover { background: #1d4ed8; transform: translateY(-2px); box-shadow: 0 6px 20px rgba(37,99,235,.5); }
.btn-secondary {
  display: inline-block; background: rgba(255,255,255,.1); color: #fff;
  padding: 14px 32px; border-radius: 8px; font-size: 16px; font-weight: 600;
  border: 1px solid rgba(255,255,255,.25); transition: background .2s, transform .15s;
}
.btn-secondary:hover { background: rgba(255,255,255,.2); transform: translateY(-2px); }
.platform-icons {
  display: flex; justify-content: center; gap: 24px; margin-top: 20px;
}
.platform-icon {
  display: flex; flex-direction: column; align-items: center; gap: 6px;
  color: rgba(255,255,255,.7); font-size: 12px; transition: color .2s;
}
.platform-icon:hover { color: #fff; }
.platform-icon svg { width: 32px; height: 32px; fill: currentColor; }

/* === Section Common === */
.section { padding: 80px 0; }
.section-alt { background: #F8FAFC; }
.section-dark { background: #1E293B; color: #fff; }
.section-title {
  text-align: center; font-size: 32px; font-weight: 700; margin-bottom: 12px;
}
.section-desc {
  text-align: center; font-size: 16px; color: #475569; max-width: 600px; margin: 0 auto 48px;
}
.section-dark .section-desc { color: rgba(255,255,255,.7); }

/* === Features === */
.features-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px;
}
.feature-card {
  background: #fff; border-radius: 12px; padding: 32px 24px; text-align: center;
  box-shadow: 0 2px 12px rgba(0,0,0,.06); transition: transform .2s, box-shadow .2s;
  border: 1px solid #e2e8f0;
}
.feature-card:hover { transform: translateY(-4px); box-shadow: 0 8px 24px rgba(0,0,0,.1); }
.feature-icon {
  width: 64px; height: 64px; margin: 0 auto 20px;
  background: linear-gradient(135deg, #eff6ff, #dbeafe); border-radius: 16px;
  display: flex; align-items: center; justify-content: center;
}
.feature-icon svg { width: 32px; height: 32px; fill: #2563EB; }
.feature-card h3 { font-size: 18px; font-weight: 700; margin-bottom: 10px; }
.feature-card p { font-size: 14px; color: #475569; line-height: 1.6; }

/* === Download Section === */
.download-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px;
}
.download-card {
  background: #fff; border-radius: 12px; padding: 36px 24px; text-align: center;
  box-shadow: 0 2px 12px rgba(0,0,0,.06); border: 1px solid #e2e8f0;
  transition: transform .2s, box-shadow .2s;
}
.download-card:hover { transform: translateY(-4px); box-shadow: 0 8px 24px rgba(0,0,0,.1); }
.download-card-icon {
  width: 56px; height: 56px; margin: 0 auto 16px;
  display: flex; align-items: center; justify-content: center;
}
.download-card-icon svg { width: 48px; height: 48px; }
.download-card h3 { font-size: 18px; font-weight: 700; margin-bottom: 6px; }
.download-card .version { font-size: 13px; color: #94a3b8; margin-bottom: 20px; }
.download-card .btn-download {
  display: inline-block; background: #2563EB; color: #fff;
  padding: 10px 28px; border-radius: 6px; font-size: 15px; font-weight: 600;
  transition: background .2s, transform .15s;
}
.download-card .btn-download:hover { background: #1d4ed8; transform: translateY(-1px); }
.download-card .req { font-size: 12px; color: #94a3b8; margin-top: 12px; }

/* === Testimonials === */
.testimonials-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px;
}
.testimonial-card {
  background: #fff; border-radius: 12px; padding: 28px; border: 1px solid #e2e8f0;
}
.testimonial-stars { color: #F59E0B; font-size: 16px; margin-bottom: 12px; letter-spacing: 2px; }
.testimonial-text { font-size: 14px; color: #475569; line-height: 1.7; margin-bottom: 16px; font-style: italic; }
.testimonial-author { display: flex; align-items: center; gap: 12px; }
.testimonial-avatar {
  width: 40px; height: 40px; border-radius: 50%; background: #dbeafe;
  display: flex; align-items: center; justify-content: center;
  color: #2563EB; font-weight: 700; font-size: 16px;
}
.testimonial-name { font-size: 14px; font-weight: 600; }
.testimonial-source { font-size: 12px; color: #94a3b8; }

/* === Updates / Changelog === */
.changelog-list { max-width: 720px; margin: 0 auto; }
.changelog-item {
  display: flex; gap: 20px; padding: 24px 0; border-bottom: 1px solid #e2e8f0;
}
.changelog-item:last-child { border-bottom: none; }
.changelog-date {
  min-width: 100px; font-size: 13px; color: #94a3b8; font-weight: 600; padding-top: 2px;
}
.changelog-body h4 { font-size: 16px; font-weight: 700; margin-bottom: 6px; }
.changelog-body p { font-size: 14px; color: #475569; line-height: 1.6; }
.changelog-tag {
  display: inline-block; background: #eff6ff; color: #2563EB; font-size: 12px;
  padding: 2px 10px; border-radius: 4px; font-weight: 600; margin-bottom: 8px;
}

/* === FAQ === */
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item {
  background: #fff; border-radius: 12px; padding: 28px 32px; margin-bottom: 20px;
  border: 1px solid #e2e8f0; box-shadow: 0 1px 4px rgba(0,0,0,.04);
}
.faq-item h3 {
  font-size: 18px; font-weight: 700; margin-bottom: 16px; color: #1E293B;
  padding-bottom: 12px; border-bottom: 2px solid #eff6ff;
}
.faq-item .faq-answer { font-size: 15px; color: #475569; line-height: 1.8; }
.faq-item .faq-answer p { margin-bottom: 12px; }
.faq-steps { padding-left: 0; counter-reset: step; }
.faq-steps li {
  counter-increment: step; padding: 8px 0 8px 40px; position: relative;
  font-size: 15px; color: #475569; line-height: 1.7;
}
.faq-steps li::before {
  content: counter(step);
  position: absolute; left: 0; top: 8px;
  width: 28px; height: 28px; background: #eff6ff; color: #2563EB;
  border-radius: 50%; display: flex; align-items: center; justify-content: center;
  font-size: 13px; font-weight: 700;
}

/* === About === */
.about-hero {
  padding: 140px 0 60px; background: linear-gradient(135deg, #1E293B, #1e3a5f);
  color: #fff; text-align: center;
}
.about-hero h1 { font-size: 40px; font-weight: 800; margin-bottom: 16px; }
.about-hero p { font-size: 18px; color: rgba(255,255,255,.7); max-width: 600px; margin: 0 auto; }
.about-content { max-width: 800px; margin: 0 auto; }
.about-content h2 { font-size: 24px; font-weight: 700; margin: 32px 0 16px; }
.about-content p { font-size: 15px; color: #475569; line-height: 1.8; margin-bottom: 16px; }
.about-stats {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; margin: 40px 0;
}
.about-stat {
  text-align: center; padding: 28px; background: #F8FAFC; border-radius: 12px;
}
.about-stat .num { font-size: 36px; font-weight: 800; color: #2563EB; }
.about-stat .label { font-size: 14px; color: #475569; margin-top: 4px; }

/* === Product Page === */
.product-hero {
  padding: 140px 0 60px; background: linear-gradient(135deg, #1E293B, #1e3a5f);
  color: #fff; text-align: center;
}
.product-hero h1 { font-size: 40px; font-weight: 800; margin-bottom: 16px; }
.product-hero p { font-size: 18px; color: rgba(255,255,255,.7); max-width: 600px; margin: 0 auto; }
.product-detail { max-width: 800px; margin: 0 auto; }
.product-detail h2 { font-size: 24px; font-weight: 700; margin: 32px 0 16px; color: #1E293B; }
.product-detail p { font-size: 15px; color: #475569; line-height: 1.8; margin-bottom: 16px; }
.product-features-list { margin: 24px 0; }
.product-features-list li {
  padding: 12px 0 12px 32px; position: relative; font-size: 15px; color: #475569; line-height: 1.7;
}
.product-features-list li::before {
  content: '\2713'; position: absolute; left: 0; top: 12px;
  color: #10B981; font-weight: 700; font-size: 18px;
}

/* === Legal Pages === */
.legal-hero {
  padding: 140px 0 40px; background: linear-gradient(135deg, #1E293B, #1e3a5f);
  color: #fff; text-align: center;
}
.legal-hero h1 { font-size: 36px; font-weight: 800; margin-bottom: 8px; }
.legal-hero p { font-size: 14px; color: rgba(255,255,255,.5); }
.legal-content {
  max-width: 800px; margin: 0 auto; padding: 48px 20px;
}
.legal-content h2 { font-size: 20px; font-weight: 700; margin: 28px 0 12px; color: #1E293B; }
.legal-content p, .legal-content li {
  font-size: 14px; color: #475569; line-height: 1.8; margin-bottom: 12px;
}
.legal-content ul { padding-left: 20px; }
.legal-content ul li { list-style: disc; margin-bottom: 8px; }

/* === Footer === */
.site-footer {
  background: #0f172a; color: rgba(255,255,255,.7); padding: 48px 0 24px;
}
.footer-grid {
  display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; margin-bottom: 40px;
}
.footer-brand h3 { color: #fff; font-size: 20px; margin-bottom: 12px; }
.footer-brand p { font-size: 14px; line-height: 1.7; }
.footer-col h4 { color: #fff; font-size: 15px; margin-bottom: 16px; font-weight: 600; }
.footer-col a {
  display: block; font-size: 14px; color: rgba(255,255,255,.6); padding: 4px 0;
  transition: color .2s;
}
.footer-col a:hover { color: #fff; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,.1); padding-top: 24px;
  display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 12px;
}
.footer-bottom p { font-size: 13px; color: rgba(255,255,255,.4); }
.footer-bottom a { color: rgba(255,255,255,.5); font-size: 13px; }
.footer-bottom a:hover { color: #fff; }

/* === Responsive === */
@media (max-width: 1024px) {
  .features-grid, .download-grid { grid-template-columns: repeat(2, 1fr); }
  .testimonials-grid { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 768px) {
  .nav-links { display: none; }
  .nav-toggle { display: flex; }
  .nav-links.open {
    display: flex; flex-direction: column; position: absolute;
    top: 64px; left: 0; right: 0; background: #1E293B; padding: 20px;
    gap: 16px; box-shadow: 0 8px 24px rgba(0,0,0,.2);
  }
  .hero h1 { font-size: 32px; }
  .hero .subtitle { font-size: 16px; }
  .features-grid, .download-grid { grid-template-columns: 1fr; }
  .testimonials-grid { grid-template-columns: 1fr; }
  .about-stats { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .section { padding: 48px 0; }
  .section-title { font-size: 24px; }
  .hero { padding: 120px 0 60px; }
  .about-hero, .product-hero, .legal-hero { padding: 120px 0 40px; }
  .about-hero h1, .product-hero h1 { font-size: 28px; }
  .changelog-item { flex-direction: column; gap: 8px; }
  .footer-bottom { flex-direction: column; text-align: center; }
}
@media (max-width: 480px) {
  .hero h1 { font-size: 26px; }
  .hero-btns { flex-direction: column; align-items: center; }
  .platform-icons { gap: 16px; }
}