/* 全局重置 & 设计系统 (品牌深蓝+金色渐变) */
* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif; background: #f5f7fc; color: #1a2639; transition: background 0.3s, color 0.3s; line-height: 1.5; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }
img, svg { display: block; max-width: 100%; height: auto; }
.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }

/* 暗黑模式 (默认跟随系统, 可手动切换) */
body.dark { background: #0e1625; color: #e2e8f0; }
body.dark .card, body.dark .glass, body.dark header, body.dark footer { background: rgba(20, 30, 50, 0.8); backdrop-filter: blur(4px); border-color: #2a3a5a; }
body.dark .section-title { color: #f0b429; }
body.dark .btn-outline { border-color: #f0b429; color: #f0b429; }

/* 玻璃效果 & 圆角 & 阴影 */
.glass { background: rgba(255,255,255,0.6); backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px); border: 1px solid rgba(255,255,255,0.3); border-radius: 28px; box-shadow: 0 20px 40px -12px rgba(0,0,0,0.15); }
.card { background: #ffffff; border-radius: 24px; padding: 24px; box-shadow: 0 10px 25px -8px rgba(0,0,0,0.08); transition: transform 0.2s, box-shadow 0.3s; }
.card:hover { transform: translateY(-4px); box-shadow: 0 25px 40px -12px rgba(0,20,40,0.2); }
.btn { display: inline-flex; align-items: center; gap: 8px; background: linear-gradient(145deg, #f0b429, #d98c1a); color: #0b1a2f; font-weight: 600; padding: 12px 28px; border-radius: 40px; border: none; cursor: pointer; transition: all 0.2s; box-shadow: 0 8px 20px -6px rgba(210,150,30,0.3); }
.btn:hover { transform: scale(1.02); box-shadow: 0 12px 28px -6px #b57c1a; }
.btn-outline { background: transparent; border: 2px solid #0b1a2f; color: #0b1a2f; box-shadow: none; }
.btn-outline:hover { background: #0b1a2f; color: white; }

/* 渐变banner & 品牌色 */
.brand-gradient { background: linear-gradient(135deg, #0b1a2f 0%, #1c3155 50%, #2a4a7a 100%); }
.accent-gold { color: #f0b429; }
.section-title { font-size: 2rem; font-weight: 700; margin-bottom: 0.5rem; letter-spacing: -0.02em; }
.section-sub { color: #5a6b8a; max-width: 700px; }

/* 动画库 (滚动出现, 数字动画等) */
.fade-up { opacity: 0; transform: translateY(20px); transition: opacity 0.7s cubic-bezier(0.2,0.9,0.1,1), transform 0.7s cubic-bezier(0.2,0.9,0.1,1); }
.fade-up.visible { opacity: 1; transform: translateY(0); }
.count-up { display: inline-block; }

/* 导航, 吸顶, 移动菜单 */
header { position: sticky; top: 0; z-index: 100; background: rgba(255,255,255,0.75); backdrop-filter: blur(12px); border-bottom: 1px solid rgba(0,0,0,0.05); transition: background 0.3s; }
body.dark header { background: rgba(14,22,37,0.85); border-bottom-color: #2a3a5a; }
.nav-wrap { display: flex; align-items: center; justify-content: space-between; padding: 0 24px; height: 70px; max-width: 1280px; margin: 0 auto; }
.logo svg { width: 130px; height: auto; }
.nav-links { display: flex; gap: 24px; font-weight: 500; }
.nav-links a { padding: 6px 0; border-bottom: 2px solid transparent; transition: 0.2s; }
.nav-links a:hover, .nav-links a.active { border-bottom-color: #f0b429; color: #f0b429; }
.menu-toggle { display: none; background: none; border: none; font-size: 28px; cursor: pointer; }
.dark-toggle { background: none; border: none; font-size: 22px; cursor: pointer; margin-left: 16px; }
@media (max-width: 900px) {
  .nav-links { display: none; position: absolute; top: 70px; left: 0; right: 0; background: white; flex-direction: column; padding: 20px; gap: 16px; box-shadow: 0 20px 30px rgba(0,0,0,0.1); border-radius: 0 0 28px 28px; }
  body.dark .nav-links { background: #111c2e; }
  .nav-links.open { display: flex; }
  .menu-toggle { display: block; }
}

/* hero 轮播 */
.hero-carousel { position: relative; width: 100%; border-radius: 32px; overflow: hidden; margin: 24px 0; min-height: 400px; }
.hero-slide { display: none; padding: 60px 40px; align-items: center; gap: 30px; flex-wrap: wrap; }
.hero-slide.active { display: flex; }
.hero-slide .text { flex: 1 1 300px; }
.hero-slide h1 { font-size: 2.8rem; font-weight: 800; line-height: 1.2; }
.hero-slide p { font-size: 1.1rem; margin: 16px 0; opacity: 0.9; }
.hero-indicators { display: flex; justify-content: center; gap: 10px; margin-top: 16px; }
.hero-indicators span { width: 12px; height: 12px; border-radius: 50%; background: rgba(255,255,255,0.4); cursor: pointer; transition: 0.2s; }
.hero-indicators span.active { background: #f0b429; transform: scale(1.2); }

/* 网格/卡片布局 */
.grid-4 { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 24px; }
.grid-3 { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 24px; }
.grid-2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 24px; }
.flex-center { display: flex; align-items: center; justify-content: center; flex-wrap: wrap; }

/* FAQ折叠 */
.faq-item { border-bottom: 1px solid #dce2ef; padding: 16px 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; padding-top: 8px; color: #4a5a7a; }
.faq-item.open .faq-answer { max-height: 300px; }

/* 返回顶部 */
#backTop { position: fixed; bottom: 30px; right: 30px; width: 48px; height: 48px; border-radius: 50%; background: #f0b429; color: #0b1a2f; border: none; font-size: 24px; box-shadow: 0 6px 16px rgba(0,0,0,0.2); cursor: pointer; display: none; z-index: 99; }
#backTop.show { display: block; }

/* footer */
footer { background: #0b1a2f; color: #b0c4de; padding: 40px 0; margin-top: 60px; border-radius: 32px 32px 0 0; }
footer a { color: #b0c4de; }
footer a:hover { color: #f0b429; }
.footer-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px,1fr)); gap: 24px; }

/* 工具 */
.mt-4 { margin-top: 32px; }
.mb-2 { margin-bottom: 16px; }
.text-center { text-align: center; }