/* 全局重置与设计变量 */
:root {
    --bg: #f8f9fc;
    --surface: #ffffff;
    --text: #1e1e2f;
    --text-secondary: #4a4a6a;
    --primary: #1a1a2e;
    --accent: #f5c518;
    --accent-light: #fde68a;
    --shadow: 0 8px 30px rgba(0,0,0,0.06);
    --radius: 20px;
    --glass-bg: rgba(255,255,255,0.55);
    --glass-border: rgba(255,255,255,0.25);
    --gradient-hero: linear-gradient(135deg, #0f0c29, #302b63, #24243e);
    --nav-bg: rgba(255,255,255,0.7);
    --footer-bg: #0f0c29;
    --card-bg: #ffffff;
    --border-color: #e9e9f0;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}
[data-theme="dark"] {
    --bg: #0d0d1a;
    --surface: #1a1a2e;
    --text: #eef0f7;
    --text-secondary: #b0b3c5;
    --primary: #f5c518;
    --accent: #f5c518;
    --shadow: 0 8px 30px rgba(0,0,0,0.5);
    --glass-bg: rgba(26,26,46,0.7);
    --glass-border: rgba(255,255,255,0.08);
    --gradient-hero: linear-gradient(135deg, #0b0b1a, #1a1a2e, #0f0c29);
    --nav-bg: rgba(13,13,26,0.8);
    --footer-bg: #05050f;
    --card-bg: #1e1e32;
    --border-color: #2d2d4a;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
    font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    transition: background var(--transition), color var(--transition);
    scroll-behavior: smooth;
}
a { color: inherit; text-decoration: none; }
img, svg { display: block; max-width: 100%; }
ul { list-style: none; }

/* 容器 */
.container { max-width: 1280px; margin: 0 auto; padding: 0 24px; }

/* 玻璃效果 */
.glass {
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius);
}

/* 头部导航 (吸顶) */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--nav-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border-color);
    transition: background var(--transition);
}
.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}
.logo-area {
    display: flex;
    align-items: center;
    gap: 10px;
}
.logo-svg {
    width: 44px;
    height: 44px;
}
.brand-name {
    font-weight: 700;
    font-size: 1.4rem;
    letter-spacing: 1px;
    color: var(--text);
}
.brand-name span { color: var(--accent); }

.main-nav {
    display: flex;
    gap: 28px;
    font-weight: 500;
}
.main-nav a {
    position: relative;
    padding: 6px 0;
    transition: color var(--transition);
}
.main-nav a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent);
    transition: width var(--transition);
}
.main-nav a:hover::after,
.main-nav a.active::after { width: 100%; }
.main-nav a.active { color: var(--accent); }

.header-actions {
    display: flex;
    align-items: center;
    gap: 18px;
}
.dark-toggle {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text);
    transition: transform 0.2s;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--surface);
    box-shadow: var(--shadow);
}
.dark-toggle:hover { transform: scale(1.05); }
.menu-toggle {
    display: none;
    background: none;
    border: none;
    font-size: 2rem;
    color: var(--text);
    cursor: pointer;
}

/* 移动菜单 */
.mobile-nav {
    display: none;
    flex-direction: column;
    background: var(--surface);
    padding: 20px;
    border-radius: 0 0 var(--radius) var(--radius);
    box-shadow: var(--shadow);
    position: absolute;
    top: 70px;
    left: 0;
    width: 100%;
    z-index: 99;
}
.mobile-nav.open { display: flex; }
.mobile-nav a {
    padding: 14px 0;
    border-bottom: 1px solid var(--border-color);
    font-weight: 500;
}
.mobile-nav a:last-child { border-bottom: none; }

/* Hero Banner 轮播 */
.hero {
    padding: 40px 0 60px;
    background: var(--gradient-hero);
    color: #fff;
    border-radius: 0 0 40px 40px;
}
.hero-carousel {
    position: relative;
    overflow: hidden;
    border-radius: 28px;
    min-height: 420px;
    display: flex;
    align-items: center;
}
.hero-slide {
    flex: 0 0 100%;
    padding: 60px 40px;
    display: flex;
    flex-direction: column;
    gap: 20px;
    transition: opacity 0.6s;
}
.hero-slide h1 {
    font-size: clamp(2.4rem, 6vw, 4rem);
    font-weight: 800;
    line-height: 1.2;
    max-width: 700px;
}
.hero-slide p {
    font-size: 1.2rem;
    max-width: 600px;
    opacity: 0.85;
}
.hero-cta {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    background: var(--accent);
    color: #1a1a2e;
    font-weight: 700;
    padding: 14px 36px;
    border-radius: 60px;
    width: fit-content;
    transition: transform 0.2s, box-shadow 0.2s;
    box-shadow: 0 4px 14px rgba(245,197,24,0.35);
}
.hero-cta:hover { transform: translateY(-3px); box-shadow: 0 8px 24px rgba(245,197,24,0.5); }
.carousel-indicators {
    display: flex;
    gap: 12px;
    justify-content: center;
    margin-top: 24px;
}
.carousel-indicators button {
    width: 12px;
    height: 12px;
    border-radius: 20px;
    border: none;
    background: rgba(255,255,255,0.3);
    cursor: pointer;
    transition: 0.3s;
}
.carousel-indicators button.active { background: var(--accent); width: 32px; }

/* 通用section */
section { padding: 70px 0; }
.section-title {
    font-size: 2.2rem;
    font-weight: 700;
    margin-bottom: 20px;
    letter-spacing: -0.3px;
}
.section-sub {
    color: var(--text-secondary);
    margin-bottom: 40px;
    max-width: 680px;
}

/* 卡片网格 */
.grid-2, .grid-3, .grid-4 {
    display: grid;
    gap: 28px;
}
.grid-2 { grid-template-columns: repeat(auto-fit, minmax(300px,1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(260px,1fr)); }
.grid-4 { grid-template-columns: repeat(auto-fit, minmax(220px,1fr)); }

.card {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 28px 24px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    transition: transform 0.25s, box-shadow 0.3s;
}
.card:hover { transform: translateY(-6px); box-shadow: 0 16px 40px rgba(0,0,0,0.08); }

/* 数字动画 */
.stat-number {
    font-size: 2.8rem;
    font-weight: 800;
    color: var(--accent);
}

/* FAQ折叠 */
.faq-item {
    background: var(--card-bg);
    border-radius: 16px;
    margin-bottom: 16px;
    border: 1px solid var(--border-color);
    overflow: hidden;
}
.faq-question {
    padding: 20px 24px;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.faq-question::after {
    content: '+';
    font-size: 1.6rem;
    transition: transform 0.3s;
}
.faq-item.open .faq-question::after { content: '−'; }
.faq-answer {
    max-height: 0;
    overflow: hidden;
    padding: 0 24px;
    transition: max-height 0.4s ease, padding 0.3s;
    color: var(--text-secondary);
}
.faq-item.open .faq-answer {
    max-height: 300px;
    padding: 0 24px 20px;
}

/* 时间轴 (发展历程) */
.timeline {
    display: flex;
    flex-direction: column;
    gap: 24px;
}
.timeline-item {
    display: flex;
    gap: 20px;
    align-items: flex-start;
}
.timeline-year {
    font-weight: 700;
    color: var(--accent);
    min-width: 80px;
}

/* 页脚 */
.site-footer {
    background: var(--footer-bg);
    color: #ccc;
    padding: 48px 0 24px;
    border-radius: 40px 40px 0 0;
}
.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px,1fr));
    gap: 32px;
}
.footer-grid h4 { color: #fff; margin-bottom: 16px; }
.footer-grid a { color: #aaa; display: block; margin-bottom: 8px; }
.footer-grid a:hover { color: var(--accent); }
.footer-bottom {
    border-top: 1px solid #2a2a4a;
    margin-top: 32px;
    padding-top: 24px;
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    font-size: 0.9rem;
}

/* 响应式 */
@media (max-width: 900px) {
    .main-nav { display: none; }
    .menu-toggle { display: block; }
    .hero-slide { padding: 40px 20px; }
}
@media (max-width: 640px) {
    .header-inner { height: 60px; }
    .brand-name { font-size: 1.1rem; }
    .section-title { font-size: 1.8rem; }
    .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
}

/* 滚动动画 (fade-up) */
.fade-up {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.7s ease, transform 0.7s ease;
}
.fade-up.visible {
    opacity: 1;
    transform: translateY(0);
}

/* 搜索模拟 (简单) */
.search-sim {
    display: flex;
    background: var(--surface);
    border-radius: 60px;
    padding: 4px 4px 4px 20px;
    border: 1px solid var(--border-color);
    max-width: 400px;
}
.search-sim input {
    border: none;
    background: transparent;
    padding: 12px 0;
    flex: 1;
    outline: none;
    color: var(--text);
}
.search-sim button {
    background: var(--accent);
    border: none;
    border-radius: 40px;
    padding: 10px 24px;
    font-weight: 600;
    cursor: pointer;
}

/* 返回顶部 */
.back-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: var(--accent);
    color: #1a1a2e;
    border: none;
    font-size: 1.6rem;
    cursor: pointer;
    box-shadow: 0 4px 20px rgba(0,0,0,0.2);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 999;
}
.back-top.show { display: flex; }