/* 全局重置 & 品牌设计变量 */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
:root {
    --brand-primary: #0a0f2c;
    --brand-secondary: #1a2a6c;
    --brand-accent: #f0b429;
    --brand-accent-light: #f7d56e;
    --glass-bg: rgba(255,255,255,0.06);
    --glass-border: rgba(255,255,255,0.12);
    --shadow-sm: 0 8px 32px rgba(0,0,0,0.2);
    --shadow-card: 0 12px 40px rgba(0,0,0,0.25);
    --radius-card: 24px;
    --radius-btn: 60px;
    --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --transition: 0.3s cubic-bezier(0.2, 0, 0, 1);
    --bg-page: #f8faff;
    --text-primary: #171717;
    --text-secondary: #3d3d3d;
    --section-gap: 80px;
}
body.dark {
    --bg-page: #0c0f1e;
    --text-primary: #f0f2f5;
    --text-secondary: #b0b8c5;
    --glass-bg: rgba(255,255,255,0.04);
    --glass-border: rgba(255,255,255,0.08);
}
html { scroll-behavior: smooth; }
body {
    font-family: var(--font-sans);
    background: var(--bg-page);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background 0.3s, color 0.3s;
}
a { color: var(--brand-accent); text-decoration: none; transition: opacity 0.2s; }
a:hover { opacity: 0.8; }
img, svg { display: block; max-width: 100%; height: auto; }
.container { max-width: 1280px; margin: 0 auto; padding: 0 24px; }

/* 吸顶导航 + 玻璃效果 */
.site-header {
    position: fixed; top: 0; left: 0; width: 100%; z-index: 1000;
    background: rgba(10, 15, 44, 0.72);
    backdrop-filter: blur(16px) saturate(180%);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--glass-border);
    transition: background 0.3s, box-shadow 0.3s;
}
body.dark .site-header { background: rgba(8, 10, 28, 0.8); }
.header-inner {
    display: flex; align-items: center; justify-content: space-between;
    padding: 12px 24px; max-width: 1280px; margin: 0 auto;
}
.logo svg { width: 140px; height: 40px; }
.nav-links { display: flex; gap: 28px; align-items: center; }
.nav-links a {
    color: #f0f2f5; font-weight: 500; font-size: 0.95rem;
    letter-spacing: 0.3px; padding: 6px 0; border-bottom: 2px solid transparent;
    transition: border-color 0.2s, color 0.2s;
}
.nav-links a.active, .nav-links a:hover { border-bottom-color: var(--brand-accent); color: #fff; }
.dark-toggle {
    background: var(--glass-bg); border: 1px solid var(--glass-border);
    border-radius: 40px; width: 40px; height: 40px; display: flex;
    align-items: center; justify-content: center; cursor: pointer;
    color: #fff; font-size: 1.2rem; transition: 0.2s;
}
.dark-toggle:hover { background: rgba(255,255,255,0.12); }
.mobile-menu-btn { display: none; background: none; border: none; color: #fff; font-size: 2rem; cursor: pointer; }

/* 移动菜单 */
.mobile-nav {
    display: none; position: fixed; top: 68px; left: 0; width: 100%; height: 100vh;
    background: rgba(10, 15, 44, 0.96); backdrop-filter: blur(20px); z-index: 999;
    flex-direction: column; padding: 32px 24px; gap: 24px;
}
.mobile-nav.open { display: flex; }
.mobile-nav a { color: #fff; font-size: 1.4rem; font-weight: 500; border-bottom: 1px solid rgba(255,255,255,0.1); padding: 12px 0; }

/* 通用按钮 */
.btn {
    display: inline-flex; align-items: center; gap: 8px;
    background: var(--brand-accent); color: #0a0f2c; font-weight: 600;
    padding: 14px 32px; border-radius: var(--radius-btn); border: none;
    font-size: 1rem; cursor: pointer; transition: all 0.25s;
    box-shadow: 0 8px 20px rgba(240, 180, 41, 0.25);
}
.btn:hover { transform: translateY(-2px); box-shadow: 0 12px 28px rgba(240, 180, 41, 0.35); }
.btn-outline { background: transparent; border: 2px solid var(--brand-accent); color: var(--brand-accent); box-shadow: none; }
.btn-outline:hover { background: var(--brand-accent); color: #0a0f2c; }

/* Hero Banner */
.hero {
    padding: 140px 0 80px; background: linear-gradient(135deg, #0a0f2c 0%, #1a2a6c 70%, #0f1a44 100%);
    position: relative; overflow: hidden;
}
.hero::after { content: ''; position: absolute; inset: 0; background: radial-gradient(circle at 30% 40%, rgba(240,180,41,0.08), transparent 60%); }
.hero-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; align-items: center; position: relative; z-index: 2; }
.hero h1 { font-size: 3.2rem; font-weight: 700; color: #fff; line-height: 1.2; letter-spacing: -0.02em; }
.hero h1 span { color: var(--brand-accent); }
.hero p { color: rgba(255,255,255,0.8); font-size: 1.2rem; margin: 24px 0 32px; max-width: 540px; }
.hero-actions { display: flex; gap: 16px; flex-wrap: wrap; }
.hero-visual svg { width: 100%; height: auto; filter: drop-shadow(0 20px 40px rgba(0,0,0,0.3)); }

/* 卡片通用 */
.card {
    background: var(--glass-bg); backdrop-filter: blur(8px);
    border: 1px solid var(--glass-border); border-radius: var(--radius-card);
    padding: 32px; box-shadow: var(--shadow-sm); transition: transform 0.3s, box-shadow 0.3s;
}
.card:hover { transform: translateY(-6px); box-shadow: var(--shadow-card); }

/* 区段标题 */
.section-title { font-size: 2.2rem; font-weight: 600; margin-bottom: 16px; letter-spacing: -0.01em; }
.section-sub { color: var(--text-secondary); max-width: 680px; margin-bottom: 48px; }

/* 网格 */
.grid-2, .grid-3, .grid-4 { display: grid; gap: 28px; }
.grid-2 { grid-template-columns: repeat(2,1fr); }
.grid-3 { grid-template-columns: repeat(3,1fr); }
.grid-4 { grid-template-columns: repeat(4,1fr); }

/* 品牌介绍区块 */
.brand-story { display: flex; gap: 40px; align-items: center; flex-wrap: wrap; }
.brand-story > div { flex: 1; min-width: 280px; }
.milestone-list { list-style: none; margin-top: 20px; }
.milestone-list li { padding: 10px 0; border-bottom: 1px solid rgba(0,0,0,0.05); display: flex; gap: 12px; }
body.dark .milestone-list li { border-color: rgba(255,255,255,0.06); }

/* 团队卡片 */
.team-card { text-align: center; padding: 32px 16px; }
.team-card svg { width: 80px; height: 80px; margin: 0 auto 16px; border-radius: 50%; background: var(--glass-bg); padding: 8px; }

/* 案例 & 文章卡片 */
.article-card, .case-card { padding: 24px; }
.article-card h4 { margin: 12px 0 8px; }
.article-card .meta { color: var(--text-secondary); font-size: 0.85rem; }

/* FAQ折叠 */
.faq-item { border-bottom: 1px solid rgba(0,0,0,0.06); padding: 18px 0; }
body.dark .faq-item { border-color: rgba(255,255,255,0.06); }
.faq-question { display: flex; justify-content: space-between; cursor: pointer; font-weight: 600; font-size: 1.1rem; }
.faq-answer { max-height: 0; overflow: hidden; transition: max-height 0.4s ease, padding 0.3s; padding-top: 0; color: var(--text-secondary); }
.faq-item.active .faq-answer { max-height: 300px; padding-top: 16px; }

/* HowTo */
.howto-steps { counter-reset: step; }
.howto-step { display: flex; gap: 20px; margin-bottom: 24px; align-items: flex-start; }
.howto-step::before { counter-increment: step; content: counter(step); background: var(--brand-accent); color: #0a0f2c; font-weight: bold; width: 36px; height: 36px; border-radius: 50%; display: flex; align-items: center; justify-content: center; flex-shrink: 0; }

/* 轮播 */
.carousel { overflow: hidden; position: relative; }
.carousel-track { display: flex; transition: transform 0.5s ease; }
.carousel-slide { min-width: 100%; padding: 0 8px; }
.carousel-nav { display: flex; justify-content: center; gap: 12px; margin-top: 24px; }
.carousel-dot { width: 12px; height: 12px; border-radius: 50%; background: rgba(0,0,0,0.2); cursor: pointer; border: none; transition: 0.2s; }
.carousel-dot.active { background: var(--brand-accent); transform: scale(1.2); }

/* 数字动画 */
.stat-number { font-size: 2.8rem; font-weight: 700; color: var(--brand-accent); }

/* 返回顶部 */
.back-top { position: fixed; bottom: 32px; right: 32px; width: 48px; height: 48px; border-radius: 50%; background: var(--brand-accent); color: #0a0f2c; border: none; font-size: 1.6rem; cursor: pointer; box-shadow: 0 4px 16px rgba(0,0,0,0.2); display: none; z-index: 999; transition: 0.2s; }
.back-top.visible { display: flex; align-items: center; justify-content: center; }

/* footer */
.footer { background: var(--brand-primary); color: #ccc; padding: 48px 0 24px; margin-top: 80px; }
.footer a { color: #aaa; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,0.08); padding-top: 24px; margin-top: 32px; display: flex; justify-content: space-between; flex-wrap: wrap; gap: 12px; }

/* 响应式 */
@media (max-width: 1024px) {
    .hero h1 { font-size: 2.4rem; }
    .grid-4 { grid-template-columns: repeat(2,1fr); }
}
@media (max-width: 768px) {
    .nav-links { display: none; }
    .mobile-menu-btn { display: block; }
    .hero-grid { grid-template-columns: 1fr; }
    .hero h1 { font-size: 2rem; }
    .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
    .brand-story { flex-direction: column; }
    .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 480px) {
    .header-inner { padding: 8px 16px; }
    .container { padding: 0 16px; }
    .section-title { font-size: 1.8rem; }
}

/* 滚动动画 (透明过渡) */
.reveal { opacity: 0; transform: translateY(30px); transition: opacity 0.7s ease, transform 0.7s ease; }
.reveal.visible { opacity: 1; transform: translateY(0); }

/* 其他辅助 */
.text-center { text-align: center; }
.mt-24 { margin-top: 24px; }
.mb-24 { margin-bottom: 24px; }
.gap-16 { gap: 16px; }
.flex-wrap { display: flex; flex-wrap: wrap; }