/* ===== 基础重置 ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-font-smoothing: antialiased; }
body {
    font-family: -apple-system, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    color: #1d1d1f;
    background: #fff;
    line-height: 1.5;
    font-size: 17px;
}
img { max-width: 100%; height: auto; display: block; }
a { color: #0066cc; text-decoration: none; }
a:hover { text-decoration: underline; }
ul { list-style: none; }

/* ===== 布局容器 ===== */
.container { max-width: 980px; margin: 0 auto; padding: 0 22px; }
.container-wide { max-width: 1400px; margin: 0 auto; padding: 0 22px; }

/* ===== 顶部导航 ===== */
.site-nav {
    position: sticky; top: 0; z-index: 100;
    background: rgba(255,255,255,0.85);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    border-bottom: 1px solid #e8e8ed;
}
.site-nav .nav-inner {
    max-width: 1024px; margin: 0 auto;
    display: flex; align-items: center; justify-content: space-between;
    height: 44px; padding: 0 22px;
}
.site-nav .logo { color: #1d1d1f; font-size: 17px; font-weight: 600; letter-spacing: -0.02em; }
.site-nav nav ul { display: flex; gap: 28px; }
.site-nav nav a {
    color: #1d1d1f; font-size: 12px; opacity: 0.8;
    transition: opacity 0.2s;
}
.site-nav nav a:hover { opacity: 1; text-decoration: none; }

/* ===== Hero 区域 ===== */
.hero {
    background: linear-gradient(180deg, #f5f9ff 0%, #fff 100%);
    text-align: center;
    padding: 80px 22px 0;
    overflow: hidden;
}
.hero h1 {
    font-size: 56px;
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.07;
    margin-bottom: 12px;
}
.hero .tagline {
    font-size: 28px;
    font-weight: 600;
    color: #1d1d1f;
    margin-bottom: 16px;
}
.hero .price {
    font-size: 17px;
    color: #86868b;
    margin-bottom: 24px;
}
.hero .cta-group {
    display: flex; gap: 16px; justify-content: center; margin-bottom: 50px;
}
.btn {
    display: inline-block;
    padding: 12px 24px;
    border-radius: 980px;
    font-size: 17px;
    font-weight: 400;
    transition: all 0.2s;
}
.btn-primary { background: #0071e3; color: #fff; }
.btn-primary:hover { background: #0077ed; text-decoration: none; }
.btn-secondary { color: #0066cc; }
.btn-secondary:hover { text-decoration: underline; }

/* ===== 通用区块 ===== */
.section { padding: 100px 0; }
.section-gray { background: #f5f5f7; }
.section-dark { background: #000; color: #f5f5f7; }
.section h2 {
    font-size: 48px;
    font-weight: 700;
    text-align: center;
    letter-spacing: -0.02em;
    line-height: 1.08;
    margin-bottom: 20px;
}
.section .subtitle {
    font-size: 21px;
    text-align: center;
    color: #6e6e73;
    max-width: 680px;
    margin: 0 auto 50px;
    line-height: 1.52;
}
.section-dark .subtitle { color: #86868b; }

/* ===== 数据统计 ===== */
.stat-row {
    display: flex;
    justify-content: center;
    gap: 60px;
    flex-wrap: wrap;
    margin-top: 40px;
}
.stat-item { text-align: center; }
.stat-item .num {
    font-size: 56px;
    font-weight: 700;
    background: linear-gradient(90deg, #0071e3, #5e5ce6);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1;
    margin-bottom: 8px;
}
.stat-item .label { font-size: 14px; color: #86868b; }

/* ===== 功能卡片 ===== */
.feature-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
    margin-top: 40px;
}
.feature-card {
    background: #fff;
    border-radius: 20px;
    padding: 32px;
}
.section-dark .feature-card { background: #1d1d1f; }
.feature-card h3 {
    font-size: 21px;
    font-weight: 600;
    margin-bottom: 10px;
}
.feature-card p {
    font-size: 14px;
    color: #6e6e73;
    line-height: 1.6;
}

/* ===== FAQ 卡片入口 ===== */
.faq-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
    margin-top: 40px;
}
.faq-card {
    background: #fff;
    border-radius: 20px;
    padding: 28px;
    border: 1px solid #e8e8ed;
    transition: box-shadow 0.2s;
}
.faq-card:hover {
    box-shadow: 0 4px 16px rgba(0,0,0,0.08);
    text-decoration: none;
}
.faq-card h3 {
    font-size: 17px;
    font-weight: 600;
    color: #1d1d1f;
    margin-bottom: 8px;
}
.faq-card p {
    font-size: 14px;
    color: #6e6e73;
    line-height: 1.5;
}

/* ===== FAQ 文章页 ===== */
.article-page {
    padding: 60px 0 100px;
    max-width: 720px;
    margin: 0 auto;
}
.article-page h1 {
    font-size: 40px;
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.2;
    margin-bottom: 20px;
}
.article-page .meta {
    font-size: 14px;
    color: #86868b;
    margin-bottom: 40px;
    padding-bottom: 20px;
    border-bottom: 1px solid #e8e8ed;
}
.article-page h2 {
    font-size: 26px;
    font-weight: 700;
    margin: 40px 0 16px;
    letter-spacing: -0.01em;
}
.article-page p {
    font-size: 17px;
    line-height: 1.7;
    color: #1d1d1f;
    margin-bottom: 16px;
}
.article-page ul {
    margin: 16px 0;
    padding-left: 20px;
}
.article-page ul li {
    font-size: 16px;
    line-height: 1.8;
    color: #3a3a3c;
    list-style: disc;
}
.article-page .related {
    margin-top: 50px;
    padding: 30px;
    background: #f5f5f7;
    border-radius: 18px;
}
.article-page .related h3 {
    font-size: 17px;
    font-weight: 600;
    margin-bottom: 12px;
}
.article-page .related a {
    display: inline-block;
    margin: 4px 12px 4px 0;
    font-size: 15px;
}

/* ===== 404 ===== */
.error-page {
    min-height: 70vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 40px 22px;
}
.error-page .code {
    font-size: 120px;
    font-weight: 700;
    line-height: 1;
    margin-bottom: 16px;
    color: #1d1d1f;
}
.error-page h1 { font-size: 32px; font-weight: 700; margin-bottom: 12px; }
.error-page p {
    font-size: 17px; color: #6e6e73;
    max-width: 400px; margin-bottom: 30px; line-height: 1.5;
}

/* ===== 页脚 ===== */
.site-footer {
    background: #f5f5f7;
    padding: 40px 0;
    font-size: 12px;
    color: #86868b;
    line-height: 1.5;
}
.site-footer .footer-links {
    border-top: 1px solid #d2d2d7;
    padding-top: 20px;
    margin-top: 20px;
    display: flex;
    gap: 20px;
    flex-wrap: wrap;
}
.site-footer a { color: #515154; }

/* ===== 响应式 ===== */
@media (max-width: 768px) {
    .hero h1 { font-size: 40px; }
    .hero .tagline { font-size: 21px; }
    .section h2 { font-size: 32px; }
    .article-page h1 { font-size: 28px; }
    .feature-grid { grid-template-columns: 1fr; }
    .faq-grid { grid-template-columns: 1fr; }
    .stat-row { gap: 30px; }
    .stat-item .num { font-size: 40px; }
    .site-nav nav ul { gap: 16px; }
    .site-nav nav a { font-size: 11px; }
}