/* 全局重置与品牌变量 */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
:root {
  --brand-primary: #0b1a2f;
  --brand-secondary: #00b4d8;
  --brand-accent: #0077b6;
  --glass-bg: rgba(255,255,255,0.05);
  --glass-border: rgba(255,255,255,0.12);
  --shadow-sm: 0 4px 20px rgba(0,0,0,0.08);
  --shadow-lg: 0 20px 40px rgba(0,0,0,0.15);
  --radius-md: 20px;
  --radius-lg: 32px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --bg-light: #f8faff;
  --text-dark: #0b1a2f;
  --text-light: #f0f4fa;
  --card-bg: #ffffff;
  --footer-bg: #0b1a2f;
  --dark-bg: #0b0f1a;
  --dark-card: #1a1f2e;
}
body {
  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif;
  background: var(--bg-light);
  color: var(--text-dark);
  line-height: 1.6;
  transition: background 0.3s, color 0.3s;
  scroll-behavior: smooth;
}
body.dark-mode { background: var(--dark-bg); color: #e0e8f0; }
.container { max-width: 1280px; margin: 0 auto; padding: 0 24px; }
/* 吸顶导航 */
.global-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255,255,255,0.7); backdrop-filter: blur(16px);
  box-shadow: 0 2px 16px rgba(0,0,0,0.04);
  transition: background 0.3s;
}
.dark-mode .global-header { background: rgba(10,14,23,0.8); }
.header-inner { display: flex; align-items: center; justify-content: space-between; padding: 12px 0; flex-wrap: wrap; }
.logo svg { display: block; height: 44px; width: auto; }
.nav-menu { display: flex; gap: 28px; list-style: none; font-weight: 500; }
.nav-menu a { text-decoration: none; color: inherit; padding: 8px 0; border-bottom: 2px solid transparent; transition: var(--transition); }
.nav-menu a:hover, .nav-menu a.active { border-bottom-color: var(--brand-secondary); color: var(--brand-secondary); }
.mobile-toggle { display: none; background: none; border: none; font-size: 28px; cursor: pointer; color: inherit; }
.dark-toggle { background: none; border: 1px solid var(--glass-border); border-radius: 40px; padding: 8px 14px; cursor: pointer; font-size: 18px; backdrop-filter: blur(4px); }
@media (max-width: 900px) {
  .nav-menu { display: none; flex-direction: column; width: 100%; background: rgba(255,255,255,0.9); backdrop-filter: blur(20px); padding: 16px 0; border-radius: var(--radius-md); margin-top: 12px; }
  .dark-mode .nav-menu { background: rgba(10,14,23,0.95); }
  .nav-menu.open { display: flex; }
  .mobile-toggle { display: inline-block; }
}
/* 通用卡片与玻璃 */
.glass-card { background: var(--glass-bg); backdrop-filter: blur(8px); border: 1px solid var(--glass-border); border-radius: var(--radius-md); padding: 28px; box-shadow: var(--shadow-sm); transition: var(--transition); }
.glass-card:hover { box-shadow: var(--shadow-lg); transform: translateY(-4px); }
.card-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 28px; }
.section-title { font-size: 2.2rem; font-weight: 700; margin-bottom: 40px; letter-spacing: -0.02em; }
.section-sub { font-size: 1.1rem; opacity: 0.75; margin-bottom: 48px; max-width: 640px; }
.btn { display: inline-block; background: var(--brand-secondary); color: #fff; padding: 14px 36px; border-radius: 60px; font-weight: 600; text-decoration: none; transition: var(--transition); border: none; cursor: pointer; }
.btn:hover { background: var(--brand-accent); transform: scale(1.02); box-shadow: 0 12px 24px rgba(0,180,216,0.3); }
/* hero */
.hero { padding: 60px 0 80px; background: linear-gradient(135deg, #0b1a2f 0%, #003049 50%, #0077b6 100%); color: white; border-radius: 0 0 60px 60px; margin-bottom: 40px; }
.dark-mode .hero { background: linear-gradient(135deg, #050a14, #0b1a2f, #002b4a); }
.hero-grid { display: flex; align-items: center; gap: 40px; flex-wrap: wrap; }
.hero-content { flex: 1 1 400px; }
.hero h1 { font-size: 3.2rem; font-weight: 800; line-height: 1.2; margin-bottom: 24px; }
.hero p { font-size: 1.2rem; opacity: 0.85; margin-bottom: 32px; max-width: 600px; }
.hero-visual { flex: 1 1 300px; min-height: 220px; background: rgba(255,255,255,0.05); border-radius: var(--radius-lg); backdrop-filter: blur(6px); display: flex; align-items: center; justify-content: center; }
/* 动画元素 */
.fade-up { opacity: 0; transform: translateY(30px); transition: opacity 0.7s ease, transform 0.7s ease; }
.fade-up.visible { opacity: 1; transform: translateY(0); }
.count-up { font-size: 2.8rem; font-weight: 700; color: var(--brand-secondary); }
/* footer */
.site-footer { background: var(--footer-bg); color: #b0c4d9; padding: 48px 0 24px; margin-top: 80px; border-radius: 48px 48px 0 0; }
.dark-mode .site-footer { background: #050a12; }
.footer-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 32px; }
.footer-links a { color: #b0c4d9; text-decoration: none; display: block; margin: 6px 0; font-size: 0.95rem; }
.footer-links a:hover { color: white; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,0.1); padding-top: 24px; margin-top: 40px; display: flex; flex-wrap: wrap; justify-content: space-between; font-size: 0.9rem; }
/* 轮播（简易） */
.carousel { position: relative; overflow: hidden; border-radius: var(--radius-lg); }
.carousel-track { display: flex; transition: transform 0.5s ease; }
.carousel-item { min-width: 100%; padding: 40px 24px; background: rgba(0,180,216,0.08); border-radius: var(--radius-md); text-align: center; }
.carousel-nav { display: flex; justify-content: center; gap: 12px; margin-top: 20px; }
.carousel-dot { width: 12px; height: 12px; border-radius: 20px; background: var(--glass-border); border: none; cursor: pointer; transition: var(--transition); }
.carousel-dot.active { background: var(--brand-secondary); width: 32px; }
/* 折叠faq */
.faq-item { border-bottom: 1px solid var(--glass-border); padding: 20px 0; }
.faq-question { font-weight: 600; cursor: pointer; display: flex; justify-content: space-between; align-items: center; }
.faq-answer { max-height: 0; overflow: hidden; transition: max-height 0.4s ease; opacity: 0.7; }
.faq-item.open .faq-answer { max-height: 400px; margin-top: 12px; }
/* 返回顶部 */
.back-top { position: fixed; bottom: 30px; right: 30px; background: var(--brand-secondary); color: white; width: 48px; height: 48px; border-radius: 60px; display: flex; align-items: center; justify-content: center; font-size: 24px; cursor: pointer; border: none; box-shadow: var(--shadow-lg); transition: var(--transition); opacity: 0; pointer-events: none; z-index: 200; }
.back-top.show { opacity: 1; pointer-events: auto; }
/* 文章卡片等 */
.article-card { padding: 20px; background: var(--card-bg); border-radius: var(--radius-md); box-shadow: var(--shadow-sm); transition: var(--transition); }
.dark-mode .article-card { background: var(--dark-card); }
.article-card h3 { margin-bottom: 8px; }
.article-card .meta { font-size: 0.85rem; opacity: 0.6; }
.grid-2col { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 24px; }
.schema-hide { display: none; }
/* 响应式微调 */
@media (max-width: 640px) { .hero h1 { font-size: 2.2rem; } .section-title { font-size: 1.8rem; } }