/* ============================================
   BG China 官网样式
   ============================================ */

:root {
  --bg-primary: #0a0e17;
  --bg-secondary: #111827;
  --bg-card: #1a2236;
  --accent-blue: #3b82f6;
  --accent-cyan: #06b6d4;
  --accent-orange: #f97316;
  --accent-red: #ef4444;
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --border-color: #1e293b;
  --gradient-blue: linear-gradient(135deg, #3b82f6 0%, #06b6d4 100%);
  --gradient-orange: linear-gradient(135deg, #f97316 0%, #ef4444 100%);
  --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.4);
  --radius: 12px;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', Arial, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
}

a { color: var(--accent-cyan); text-decoration: none; transition: color 0.3s; }
a:hover { color: var(--accent-orange); }

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

/* ---- Navigation ---- */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  background: rgba(10, 14, 23, 0.9);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-color);
  padding: 0 2rem;
}
.nav-inner {
  max-width: 1280px; margin: 0 auto;
  display: flex; align-items: center; justify-content: space-between;
  height: 64px;
}
.nav-logo {
  font-size: 1.5rem; font-weight: 900;
  background: var(--gradient-blue);
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  letter-spacing: 2px;
}
.nav-logo span { font-size: 0.75rem; color: var(--text-muted); -webkit-text-fill-color: var(--text-muted); display: block; letter-spacing: 1px; }
.nav-links { display: flex; gap: 1.5rem; list-style: none; }
.nav-links a {
  color: var(--text-secondary); font-size: 0.9rem; font-weight: 500;
  padding: 0.5rem 0.75rem; border-radius: 8px; transition: all 0.3s;
}
.nav-links a:hover { color: var(--text-primary); background: rgba(255,255,255,0.05); }
.nav-cta {
  background: var(--gradient-orange) !important; color: white !important;
  -webkit-text-fill-color: white !important;
  font-weight: 600 !important;
  padding: 0.5rem 1.2rem !important;
  border-radius: 8px !important;
}
.nav-cta:hover { opacity: 0.9; transform: translateY(-1px); }

.mobile-toggle {
  display: none; background: none; border: none; color: var(--text-primary);
  font-size: 1.5rem; cursor: pointer;
}

/* ---- Hero ---- */
.hero {
  min-height: 100vh; display: flex; align-items: center; justify-content: center;
  padding: 6rem 2rem 4rem;
  background: radial-gradient(ellipse at 50% 0%, rgba(59, 130, 246, 0.15) 0%, transparent 60%),
              var(--bg-primary);
  text-align: center; position: relative; overflow: hidden;
}
.hero::before {
  content: ''; position: absolute; top: -50%; left: -50%; width: 200%; height: 200%;
  background: repeating-linear-gradient(0deg, transparent, transparent 49px, rgba(59,130,246,0.03) 49px, rgba(59,130,246,0.03) 50px),
              repeating-linear-gradient(90deg, transparent, transparent 49px, rgba(59,130,246,0.03) 49px, rgba(59,130,246,0.03) 50px);
  animation: gridMove 20s linear infinite;
}
@keyframes gridMove { from { transform: translate(0, 0); } to { transform: translate(50px, 50px); } }

.hero-content { position: relative; z-index: 2; max-width: 900px; }
.hero-badge {
  display: inline-flex; align-items: center; gap: 0.5rem;
  background: rgba(59, 130, 246, 0.1); border: 1px solid rgba(59, 130, 246, 0.2);
  padding: 0.5rem 1.2rem; border-radius: 50px; font-size: 0.85rem;
  color: var(--accent-cyan); margin-bottom: 2rem;
}
.hero-badge::before { content: '🇺🇸'; }
.hero h1 {
  font-size: clamp(2.5rem, 6vw, 4.5rem); font-weight: 900;
  line-height: 1.1; margin-bottom: 1.5rem;
  background: linear-gradient(135deg, #f1f5f9 0%, #94a3b8 100%);
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
}
.hero h1 em {
  font-style: normal;
  background: var(--gradient-orange);
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
}
.hero-sub {
  font-size: 1.25rem; color: var(--text-secondary); max-width: 600px;
  margin: 0 auto 2.5rem; line-height: 1.8;
}
.hero-buttons { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; }
.btn {
  display: inline-flex; align-items: center; gap: 0.5rem;
  padding: 0.9rem 2rem; border-radius: 12px; font-size: 1rem; font-weight: 600;
  cursor: pointer; border: none; transition: all 0.3s; text-decoration: none;
}
.btn-primary { background: var(--gradient-orange); color: white; }
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 10px 30px rgba(249, 115, 22, 0.3); color: white; }
.btn-outline {
  background: transparent; color: var(--text-primary);
  border: 1px solid var(--border-color);
}
.btn-outline:hover { border-color: var(--accent-blue); background: rgba(59, 130, 246, 0.1); color: var(--accent-blue); }

.hero-stats {
  display: flex; justify-content: center; gap: 3rem; margin-top: 4rem;
  padding-top: 3rem; border-top: 1px solid var(--border-color);
}
.stat { text-align: center; }
.stat-num {
  font-size: 2.5rem; font-weight: 900;
  background: var(--gradient-blue);
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
}
.stat-label { font-size: 0.85rem; color: var(--text-muted); margin-top: 0.25rem; }

/* ---- Sections ---- */
.section {
  padding: 6rem 2rem; max-width: 1280px; margin: 0 auto;
}
.section-dark { background: var(--bg-secondary); }
.section-title {
  text-align: center; margin-bottom: 4rem;
}
.section-title h2 {
  font-size: clamp(1.8rem, 4vw, 2.5rem); font-weight: 800; margin-bottom: 1rem;
}
.section-title p { color: var(--text-secondary); font-size: 1.1rem; max-width: 600px; margin: 0 auto; }

/* ---- Cards ---- */
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); gap: 2rem; }
.card {
  background: var(--bg-card); border: 1px solid var(--border-color);
  border-radius: var(--radius); padding: 2rem; transition: all 0.3s;
  position: relative; overflow: hidden;
}
.card:hover {
  transform: translateY(-4px);
  border-color: var(--accent-blue);
  box-shadow: 0 20px 40px rgba(59, 130, 246, 0.1);
}
.card-icon {
  width: 56px; height: 56px; border-radius: 12px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.5rem; margin-bottom: 1.5rem;
  background: rgba(59, 130, 246, 0.1); border: 1px solid rgba(59, 130, 246, 0.2);
}
.card h3 { font-size: 1.25rem; font-weight: 700; margin-bottom: 0.75rem; }
.card p { color: var(--text-secondary); font-size: 0.95rem; }

/* ---- Products ---- */
.products-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 2rem; }
.product-card {
  background: var(--bg-card); border: 1px solid var(--border-color);
  border-radius: var(--radius); overflow: hidden; transition: all 0.3s;
}
.product-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3);
  border-color: var(--accent-orange);
}
.product-image {
  height: 220px; background: linear-gradient(135deg, #1a2236 0%, #0f172a 100%);
  display: flex; align-items: center; justify-content: center;
  font-size: 4rem; position: relative;
}
.product-badge {
  position: absolute; top: 1rem; right: 1rem;
  background: var(--gradient-orange); color: white;
  padding: 0.3rem 0.8rem; border-radius: 6px; font-size: 0.75rem; font-weight: 600;
}
.product-info { padding: 1.5rem; }
.product-info h3 { font-size: 1.2rem; font-weight: 700; margin-bottom: 0.5rem; }
.product-info .desc { color: var(--text-secondary); font-size: 0.9rem; margin-bottom: 1rem; }
.product-specs { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-bottom: 1.5rem; }
.spec-tag {
  background: rgba(6, 182, 212, 0.1); border: 1px solid rgba(6, 182, 212, 0.2);
  padding: 0.25rem 0.6rem; border-radius: 6px; font-size: 0.75rem; color: var(--accent-cyan);
}
.product-price { display: flex; align-items: center; justify-content: space-between; }
.price { font-size: 1.5rem; font-weight: 900; color: var(--accent-orange); }
.price small { font-size: 0.8rem; color: var(--text-muted); font-weight: 400; }

/* ---- Comparison ---- */
.compare-table {
  width: 100%; border-collapse: collapse; margin-top: 2rem;
  background: var(--bg-card); border-radius: var(--radius); overflow: hidden;
}
.compare-table th, .compare-table td {
  padding: 1rem 1.5rem; text-align: left; border-bottom: 1px solid var(--border-color);
}
.compare-table th {
  background: rgba(59, 130, 246, 0.1); font-weight: 700;
  color: var(--accent-cyan); font-size: 0.9rem;
}
.compare-table td { color: var(--text-secondary); }
.compare-table tr:hover td { background: rgba(255,255,255,0.02); }
.compare-table .highlight {
  background: rgba(249, 115, 22, 0.05);
  border-left: 3px solid var(--accent-orange);
}
.compare-table .check { color: #22c55e; }
.compare-table .cross { color: var(--accent-red); }

/* ---- FAQ ---- */
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item {
  background: var(--bg-card); border: 1px solid var(--border-color);
  border-radius: var(--radius); margin-bottom: 1rem; overflow: hidden;
  transition: all 0.3s;
}
.faq-item:hover { border-color: var(--accent-blue); }
.faq-q {
  padding: 1.5rem; cursor: pointer; font-weight: 600;
  display: flex; justify-content: space-between; align-items: center;
}
.faq-q::after { content: '+'; font-size: 1.5rem; color: var(--accent-blue); transition: transform 0.3s; }
.faq-item.open .faq-q::after { content: '−'; }
.faq-a {
  padding: 0 1.5rem; max-height: 0; overflow: hidden;
  color: var(--text-secondary); transition: all 0.3s;
}
.faq-item.open .faq-a { padding: 0 1.5rem 1.5rem; max-height: 500px; }

/* ---- CTA Banner ---- */
.cta-banner {
  background: var(--bg-card); border: 1px solid var(--border-color);
  border-radius: var(--radius); padding: 4rem 3rem; text-align: center;
  position: relative; overflow: hidden;
}
.cta-banner::before {
  content: ''; position: absolute; inset: 0;
  background: radial-gradient(ellipse at center, rgba(249, 115, 22, 0.1) 0%, transparent 70%);
}
.cta-banner h2 { font-size: 2rem; font-weight: 800; margin-bottom: 1rem; position: relative; }
.cta-banner p { color: var(--text-secondary); margin-bottom: 2rem; position: relative; }

/* ---- Footer ---- */
.footer {
  background: var(--bg-secondary); border-top: 1px solid var(--border-color);
  padding: 4rem 2rem 2rem;
}
.footer-inner {
  max-width: 1280px; margin: 0 auto;
  display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 2rem;
}
.footer h4 { font-size: 1rem; font-weight: 700; margin-bottom: 1rem; color: var(--text-primary); }
.footer ul { list-style: none; }
.footer li { margin-bottom: 0.5rem; }
.footer a { color: var(--text-muted); font-size: 0.9rem; }
.footer a:hover { color: var(--accent-cyan); }
.footer-bottom {
  max-width: 1280px; margin: 3rem auto 0; padding-top: 2rem;
  border-top: 1px solid var(--border-color);
  text-align: center; color: var(--text-muted); font-size: 0.85rem;
}

/* ---- Page Header ---- */
.page-header {
  padding: 8rem 2rem 4rem; text-align: center;
  background: radial-gradient(ellipse at 50% 0%, rgba(59, 130, 246, 0.15) 0%, transparent 60%),
              var(--bg-primary);
}
.page-header h1 {
  font-size: clamp(2rem, 5vw, 3rem); font-weight: 900; margin-bottom: 1rem;
}
.page-header p { color: var(--text-secondary); font-size: 1.1rem; max-width: 600px; margin: 0 auto; }
.breadcrumb {
  display: flex; align-items: center; justify-content: center; gap: 0.5rem;
  margin-bottom: 2rem; font-size: 0.85rem; color: var(--text-muted);
}
.breadcrumb a { color: var(--text-muted); }

/* ---- Responsive ---- */
@media (max-width: 768px) {
  .nav-links { display: none; }
  .mobile-toggle { display: block; }
  .hero-stats { gap: 1.5rem; flex-wrap: wrap; }
  .stat-num { font-size: 1.8rem; }
  .cards { grid-template-columns: 1fr; }
  .compare-table { font-size: 0.85rem; }
  .compare-table th, .compare-table td { padding: 0.75rem; }
  .cta-banner { padding: 3rem 1.5rem; }
  .footer-inner { grid-template-columns: 1fr 1fr; }
}

/* ---- Animations ---- */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(30px); }
  to { opacity: 1; transform: translateY(0); }
}
.animate { animation: fadeInUp 0.6s ease-out forwards; }
.animate-delay-1 { animation-delay: 0.1s; opacity: 0; }
.animate-delay-2 { animation-delay: 0.2s; opacity: 0; }
.animate-delay-3 { animation-delay: 0.3s; opacity: 0; }