/* 全局重置与品牌变量 */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
:root {
    --brand-primary: #002856;
    --brand-secondary: #0A6EBD;
    --brand-accent: #F0B90B;
    --brand-light: #E6F2FF;
    --glass-bg: rgba(255,255,255,0.15);
    --glass-border: rgba(255,255,255,0.2);
    --shadow-sm: 0 8px 20px rgba(0,0,0,0.04);
    --shadow-md: 0 16px 40px rgba(0,0,0,0.08);
    --shadow-lg: 0 30px 60px rgba(0,0,0,0.12);
    --radius: 24px;
    --radius-sm: 12px;
    --transition: 0.25s ease;
    --bg-body: #ffffff;
    --bg-section: #f9fafc;
    --text-primary: #0b1a2e;
    --text-secondary: #2c3e50;
    --text-muted: #5a6b7f;
    --dark-bg: #0b1320;
    --dark-surface: #1a2635;
    --dark-text: #e4e9f2;
}
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    background: var(--bg-body);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background 0.3s, color 0.3s;
    scroll-behavior: smooth;
}
body.dark-mode { background: var(--dark-bg); color: var(--dark-text); }
body.dark-mode .section-light { background: var(--dark-surface); }
.container { max-width: 1280px; margin: 0 auto; padding: 0 24px; }
/* glass morphism */
.glass-card {
    background: var(--glass-bg);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
    transition: transform 0.2s, box-shadow 0.2s;
}
.glass-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); }
/* 渐变Banner */
.hero-gradient {
    background: linear-gradient(135deg, #002856 0%, #0a6ebd 70%, #1a8fe0 100%);
    color: white;
}
/* 圆角组件 */
.btn-rounded {
    border-radius: 60px;
    padding: 14px 36px;
    border: none;
    background: var(--brand-accent);
    color: #002856;
    font-weight: 600;
    font-size: 1rem;
    transition: all 0.2s;
    cursor: pointer;
}
.btn-rounded:hover { transform: scale(1.02); box-shadow: 0 8px 24px rgba(240,185,11,0.3); }
.section-title { font-size: 2.2rem; font-weight: 700; margin-bottom: 1.5rem; letter-spacing: -0.01em; }
.subtitle { font-size: 1.1rem; color: var(--text-muted); max-width: 720px; }
.dark-mode .subtitle { color: #a0b3cc; }
/* 网格卡片 */
.grid-3 { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 32px; }
.grid-4 { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 24px; }
.card-padding { padding: 28px 24px; }
/* 动画入场 */
.fade-up { opacity: 0; transform: translateY(30px); transition: opacity 0.6s ease, transform 0.6s ease; }
.fade-up.visible { opacity: 1; transform: translateY(0); }
/* 滚动数字 */
.count-num { font-size: 2.8rem; font-weight: 800; color: var(--brand-secondary); }
/* 轮播 */
.carousel-container { position: relative; overflow: hidden; border-radius: var(--radius); }
.carousel-slide { display: flex; transition: transform 0.5s ease; }
.carousel-item { min-width: 100%; padding: 40px 24px; }
/* 吸顶导航 */
.sticky-header {
    position: sticky; top: 0; z-index: 100;
    background: rgba(255,255,255,0.75);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid rgba(0,0,0,0.05);
}
.dark-mode .sticky-header { background: rgba(11,19,32,0.8); border-color: rgba(255,255,255,0.08); }
.nav-link { font-weight: 500; padding: 8px 16px; border-radius: 40px; transition: background 0.2s; }
.nav-link:hover, .nav-link.active { background: rgba(10,110,189,0.12); }
.mobile-menu-btn { display: none; background: none; border: none; font-size: 1.8rem; cursor: pointer; }
@media (max-width: 900px) {
    .nav-links { display: none; }
    .mobile-menu-btn { display: block; }
    .nav-links.open { display: flex; flex-direction: column; gap: 8px; background: var(--bg-body); padding: 20px; border-radius: var(--radius-sm); box-shadow: var(--shadow-lg); position: absolute; top: 70px; right: 24px; width: 240px; }
    .dark-mode .nav-links.open { background: var(--dark-surface); }
}
/* 暗黑切换 */
.dark-toggle {
    background: none; border: 1px solid var(--text-muted); border-radius: 40px;
    width: 44px; height: 44px; display: flex; align-items: center; justify-content: center;
    cursor: pointer; transition: 0.2s;
}
.dark-toggle:hover { background: rgba(0,0,0,0.05); }
.dark-mode .dark-toggle { border-color: #a0b3cc; }
/* 返回顶部 */
#backToTop {
    position: fixed; bottom: 40px; right: 30px; width: 52px; height: 52px;
    background: var(--brand-primary); color: white; border: none; border-radius: 50%;
    font-size: 1.8rem; cursor: pointer; box-shadow: var(--shadow-md); z-index: 99;
    display: none; transition: 0.2s;
}
#backToTop:hover { background: var(--brand-secondary); transform: scale(1.05); }
/* FAQ折叠 */
.faq-item { border-bottom: 1px solid rgba(0,0,0,0.06); padding: 16px 0; }
.faq-question { font-weight: 600; cursor: pointer; display: flex; justify-content: space-between; }
.faq-answer { max-height: 0; overflow: hidden; transition: max-height 0.3s ease; color: var(--text-muted); }
.faq-item.open .faq-answer { max-height: 300px; padding-top: 12px; }
/* 搜索模拟 */
.search-sim {
    background: var(--bg-section); border-radius: 60px; padding: 8px 20px;
    display: flex; align-items: center; gap: 8px; max-width: 360px;
    border: 1px solid rgba(0,0,0,0.06);
}
.dark-mode .search-sim { background: #1f2a3a; }
/* footer */
.footer-link { color: var(--text-muted); text-decoration: none; font-size: 0.9rem; }
.footer-link:hover { color: var(--brand-secondary); }
/* 其他 */
.bg-section-light { background: var(--bg-section); }
.dark-mode .bg-section-light { background: var(--dark-surface); }
.avatar-stack { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.badge { background: var(--brand-light); color: var(--brand-primary); padding: 4px 14px; border-radius: 60px; font-size: 0.8rem; }
.dark-mode .badge { background: #1a2a44; color: #b8d0f0; }
.mt-4 { margin-top: 2rem; }
.mb-4 { margin-bottom: 2rem; }
.text-center { text-align: center; }
.flex-between { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; }
.gap-2 { gap: 12px; }