/* === 全局重置 & 设计变量 === */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
:root {
  --brand-primary: #003057;
  --brand-accent: #FFD700;
  --brand-gradient: linear-gradient(135deg, #001f3f 0%, #003057 50%, #0a4b7a 100%);
  --glass-bg: rgba(255,255,255,0.08);
  --glass-border: rgba(255,255,255,0.15);
  --shadow-sm: 0 8px 20px rgba(0,0,0,0.06);
  --shadow-lg: 0 20px 40px rgba(0,0,0,0.12);
  --radius-card: 24px;
  --radius-btn: 40px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --font-sans: system-ui, -apple-system, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  --text-light: #f0f4fa;
  --text-dark: #1a2634;
  --bg-dark: #0b1926;
  --bg-light: #f9fcff;
}
body {
  font-family: var(--font-sans);
  background: var(--bg-light);
  color: var(--text-dark);
  line-height: 1.6;
  scroll-behavior: smooth;
  transition: background 0.3s, color 0.3s;
}
body.dark-mode {
  background: var(--bg-dark);
  color: var(--text-light);
}
a { color: inherit; text-decoration: none; }
img, svg { display: block; max-width: 100%; height: auto; }
ul { list-style: none; }
.container { max-width: 1280px; margin: 0 auto; padding: 0 24px; }
.section-title { font-size: 2.2rem; font-weight: 700; margin-bottom: 0.5rem; letter-spacing: -0.02em; }
.section-sub { font-size: 1.1rem; opacity: 0.75; margin-bottom: 2.5rem; }
.glass-card {
  background: var(--glass-bg);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-card);
  box-shadow: var(--shadow-sm);
  padding: 2rem;
  transition: transform 0.25s, box-shadow 0.3s;
}
.glass-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  background: var(--brand-accent); color: #001f3f; font-weight: 600;
  padding: 12px 32px; border-radius: var(--radius-btn);
  transition: all 0.25s; border: none; cursor: pointer;
}
.btn:hover { background: #ffea70; transform: scale(1.02); box-shadow: 0 8px 18px rgba(255,215,0,0.3); }
.dark-mode .btn { color: #001f3f; }
/* 滚动动画初始 */
.reveal { opacity: 0; transform: translateY(30px); transition: opacity 0.7s ease, transform 0.7s ease; }
.reveal.visible { opacity: 1; transform: translateY(0); }
/* 头部导航 */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(0,48,87,0.85); backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(255,255,255,0.08);
  padding: 0 24px; transition: background 0.3s;
}
.dark-mode .site-header { background: rgba(10,25,47,0.9); }
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  max-width: 1280px; margin: 0 auto; height: 70px;
}
.logo svg { height: 38px; width: auto; }
.nav-links { display: flex; gap: 28px; font-weight: 500; }
.nav-links a { position: relative; padding: 4px 0; transition: color 0.2s; }
.nav-links a::after { content: ''; position: absolute; bottom: -2px; left: 0; width: 0; height: 2px; background: var(--brand-accent); transition: width 0.25s; }
.nav-links a:hover::after, .nav-links a.active::after { width: 100%; }
.nav-links a.active { color: var(--brand-accent); }
.dark-toggle { background: none; border: 1px solid rgba(255,255,255,0.25); border-radius: 30px; width: 40px; height: 40px; display: flex; align-items: center; justify-content: center; cursor: pointer; font-size: 1.2rem; transition: 0.2s; }
.dark-toggle:hover { background: rgba(255,255,255,0.1); }
.mobile-menu-btn { display: none; background: none; border: none; color: white; font-size: 1.8rem; cursor: pointer; }
/* 移动菜单 */
.mobile-nav { display: none; position: fixed; top: 70px; left: 0; width: 100%; background: rgba(0,30,60,0.98); backdrop-filter: blur(16px); padding: 24px; z-index: 99; flex-direction: column; gap: 16px; }
.mobile-nav.open { display: flex; }
.mobile-nav a { color: white; font-size: 1.2rem; border-bottom: 1px solid rgba(255,255,255,0.05); padding: 10px 0; }
/* Hero */
.hero {
  background: var(--brand-gradient);
  color: white; padding: 80px 0 100px; position: relative; overflow: hidden;
}
.hero::after { content: ''; position: absolute; inset: 0; background: radial-gradient(circle at 80% 30%, rgba(255,215,0,0.08) 0%, transparent 60%); pointer-events: none; }
.hero-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; align-items: center; }
.hero h1 { font-size: 3.2rem; font-weight: 800; line-height: 1.2; letter-spacing: -0.01em; }
.hero h1 span { color: var(--brand-accent); }
.hero p { font-size: 1.2rem; opacity: 0.85; margin: 20px 0 30px; max-width: 500px; }
.hero-badge { display: inline-block; background: rgba(255,215,0,0.15); padding: 6px 16px; border-radius: 40px; font-size: 0.9rem; margin-bottom: 20px; border: 1px solid rgba(255,215,0,0.2); }
.hero-visual svg { width: 100%; max-width: 480px; margin: 0 auto; filter: drop-shadow(0 20px 30px rgba(0,0,0,0.2)); }
/* 轮播 */
.carousel { position: relative; overflow: hidden; border-radius: var(--radius-card); background: #eef3f9; min-height: 300px; }
.dark-mode .carousel { background: #1f2c3a; }
.carousel-track { display: flex; transition: transform 0.5s ease; }
.carousel-slide { min-width: 100%; padding: 2rem; display: flex; flex-direction: column; justify-content: center; }
.carousel-indicators { display: flex; justify-content: center; gap: 12px; margin-top: 20px; }
.carousel-indicators button { width: 12px; height: 12px; border-radius: 20px; border: none; background: #b0c4de; cursor: pointer; transition: 0.2s; }
.carousel-indicators button.active { background: var(--brand-accent); width: 28px; }
/* 数字动画 */
.stat-number { font-size: 2.8rem; font-weight: 700; color: var(--brand-primary); }
.dark-mode .stat-number { color: var(--brand-accent); }
/* FAQ折叠 */
.faq-item { border-bottom: 1px solid rgba(0,0,0,0.06); padding: 1rem 0; }
.dark-mode .faq-item { border-color: rgba(255,255,255,0.08); }
.faq-question { display: flex; justify-content: space-between; align-items: center; font-weight: 600; cursor: pointer; padding: 0.5rem 0; }
.faq-answer { max-height: 0; overflow: hidden; transition: max-height 0.35s ease, padding 0.2s; padding: 0 0.5rem; }
.faq-answer.open { max-height: 400px; padding: 0.75rem 0.5rem; }
.faq-toggle { font-size: 1.4rem; transition: transform 0.2s; }
.faq-toggle.open { transform: rotate(45deg); }
/* 文章卡片 */
.article-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 24px; margin-top: 20px; }
.article-card { background: white; border-radius: var(--radius-card); padding: 1.5rem; box-shadow: var(--shadow-sm); transition: 0.2s; }
.dark-mode .article-card { background: #1a283a; }
.article-card h4 { font-size: 1.2rem; margin: 10px 0 6px; }
.article-card .meta { font-size: 0.8rem; opacity: 0.6; }
.read-more { color: var(--brand-primary); font-weight: 600; display: inline-block; margin-top: 12px; }
.dark-mode .read-more { color: var(--brand-accent); }
/* 联系方式区域 */
.contact-block { background: var(--brand-gradient); color: white; border-radius: 40px; padding: 3rem; margin: 60px 0; }
.contact-flex { display: flex; flex-wrap: wrap; gap: 30px; justify-content: space-between; }
/* footer */
.site-footer { background: #001a2c; color: #b0c8da; padding: 40px 0; margin-top: 60px; }
.dark-mode .site-footer { background: #030f1a; }
.footer-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px,1fr)); gap: 30px; }
.footer-grid a { color: #b0c8da; display: block; margin: 6px 0; }
.footer-grid a:hover { color: white; }
.footer-copy { border-top: 1px solid rgba(255,255,255,0.05); margin-top: 30px; padding-top: 20px; text-align: center; font-size: 0.9rem; }
/* 响应式 */
@media (max-width: 1024px) { .hero-grid { grid-template-columns: 1fr; } .hero h1 { font-size: 2.4rem; } }
@media (max-width: 768px) {
  .nav-links { display: none; }
  .mobile-menu-btn { display: block; }
  .section-title { font-size: 1.8rem; }
  .hero { padding: 60px 0; }
}
@media (max-width: 480px) { .hero h1 { font-size: 1.8rem; } .container { padding: 0 16px; } }
/* 返回顶部 */
.back-top { position: fixed; bottom: 30px; right: 30px; background: var(--brand-primary); color: white; width: 48px; height: 48px; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-size: 1.5rem; box-shadow: var(--shadow-lg); opacity: 0; visibility: hidden; transition: 0.3s; cursor: pointer; border: none; z-index: 50; }
.back-top.show { opacity: 1; visibility: visible; }
.back-top:hover { background: #002244; }
/* 搜索模拟 */
.search-box { display: flex; max-width: 400px; border-radius: 60px; overflow: hidden; background: white; box-shadow: 0 4px 10px rgba(0,0,0,0.02); }
.dark-mode .search-box { background: #1e2b3a; }
.search-box input { border: none; padding: 12px 20px; flex: 1; background: transparent; color: inherit; outline: none; }
.search-box button { background: var(--brand-accent); border: none; padding: 0 20px; font-weight: 600; cursor: pointer; }
/* 额外工具类 */
.mt-2 { margin-top: 2rem; }
.grid-2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px,1fr)); gap: 24px; }
.text-center { text-align: center; }
.brand-accent { color: var(--brand-accent); }
.rounded-full { border-radius: 999px; }