:root {
    --bg-canvas: #fafafa;
    --bg-surface: #ffffff;
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --brand-main: #24a1de;
    --brand-dark: #1d82b3;
    --border-muted: #cbd5e1;
    --border-subtle: #f1f5f9;
    --code-bg: #0f172a;
    --mono-font: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
}
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "SF Pro Display", Helvetica, Arial, sans-serif;
    color: var(--text-primary);
    background-color: var(--bg-canvas);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
}
header {
    border-bottom: 1px solid var(--border-muted);
    position: sticky;
    top: 0;
    background: rgba(250, 250, 250, 0.85);
    backdrop-filter: blur(12px);
    z-index: 100;
}
.nav-wrapper {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 18px 24px;
}
.brand-logo {
    display: flex;
    align-items: center;
    gap: 12px;
    text-decoration: none;
}
.brand-logo svg {
    width: 30px;
    height: 30px;
    fill: var(--brand-main);
}
.brand-name {
    font-size: 19px;
    font-weight: 800;
    color: var(--text-primary);
    letter-spacing: -0.5px;
}
.brand-version {
    font-size: 11px;
    font-weight: 700;
    background: #e0f2fe;
    color: #0369a1;
    padding: 1px 6px;
    border-radius: 4px;
}
nav {
    display: flex;
    gap: 40px;
}
nav a {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 600;
    transition: color 0.15s;
    font-size: 14px;
}
nav a:hover, nav a.active {
    color: var(--brand-main);
}
.faq-hero {
    max-width: 1400px;
    margin: 0 auto;
    padding: 120px 24px 60px 24px;
}
.hero-content {
    max-width: 850px;
}
.hero-content h1 {
    font-size: 64px;
    font-weight: 900;
    line-height: 1.05;
    letter-spacing: -3px;
    margin-bottom: 28px;
}
.hero-content p {
    font-size: 19px;
    color: var(--text-secondary);
    line-height: 1.7;
}
.section-header-tag {
    font-size: 12px;
    font-weight: 800;
    text-transform: uppercase;
    color: var(--brand-main);
    letter-spacing: 2px;
    margin-bottom: 16px;
    display: block;
}

/* ========== 快速搜索与热门问题 ========== */
.quick-help-section {
    padding: 0 24px 40px 24px;
    background: transparent;
}
.quick-help-section .section-inner {
    max-width: 1400px;
    margin: 0 auto;
}
.quick-search-box {
    margin-bottom: 24px;
}
.search-form {
    display: flex;
    max-width: 600px;
    gap: 12px;
}
.search-input {
    flex: 1;
    padding: 14px 20px;
    border: 1px solid var(--border-muted);
    border-radius: 8px;
    font-size: 15px;
    background: #ffffff;
    outline: none;
    transition: border-color 0.2s;
}
.search-input:focus {
    border-color: var(--brand-main);
}
.search-btn {
    background-color: var(--text-primary);
    color: #ffffff;
    border: none;
    padding: 0 24px;
    border-radius: 8px;
    font-weight: 700;
    font-size: 14px;
    cursor: pointer;
    transition: background-color 0.15s;
}
.search-btn:hover {
    background-color: #1e293b;
}
.popular-topics {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 12px;
}
.popular-label {
    font-size: 14px;
    font-weight: 700;
    color: var(--text-secondary);
    margin-right: 4px;
}
.popular-chip {
    display: inline-block;
    padding: 8px 16px;
    background: #ffffff;
    border: 1px solid var(--border-muted);
    border-radius: 20px;
    font-size: 13px;
    font-weight: 600;
    color: var(--text-primary);
    text-decoration: none;
    transition: background-color 0.2s, border-color 0.2s;
}
.popular-chip:hover {
    background-color: #eef2ff;
    border-color: var(--brand-main);
    color: var(--brand-main);
}

/* ========== FAQ 主体 ========== */
.faq-body-section {
    background: #ffffff;
    border-top: 1px solid var(--border-muted);
    border-bottom: 1px solid var(--border-muted);
    padding: 100px 0;
}
.section-inner {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 24px;
}
.asymmetric-qa-matrix {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 64px;
    padding-bottom: 80px;
    margin-bottom: 80px;
    border-bottom: 1px solid var(--border-subtle);
}
.asymmetric-qa-matrix:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}
@media (max-width: 960px) {
    .asymmetric-qa-matrix {
        grid-template-columns: 1fr;
        gap: 24px;
    }
}
.qa-topic {
    font-size: 24px;
    font-weight: 850;
    letter-spacing: -0.5px;
    color: var(--text-primary);
    position: sticky;
    top: 100px;
    white-space: pre-line;
}
.qa-content h3 {
    font-size: 19px;
    font-weight: 800;
    margin-bottom: 16px;
    color: var(--text-primary);
}
.qa-content p {
    font-size: 15px;
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 32px;
}
.qa-content p strong {
    color: var(--text-primary);
}

/* ========== Footer ========== */
footer {
    background-color: #ffffff;
    color: var(--text-primary);
    padding: 100px 24px 60px 24px;
    border-top: 1px solid var(--border-muted);
}
.footer-upper {
    max-width: 1400px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1.5fr repeat(3, 1fr);
    gap: 60px;
    padding-bottom: 60px;
}
@media (max-width: 960px) {
    .footer-upper {
        grid-template-columns: repeat(2, 1fr);
        gap: 40px;
    }
}
@media (max-width: 480px) {
    .footer-upper {
        grid-template-columns: 1fr;
    }
}
.footer-manifesto h4 {
    font-size: 16px;
    font-weight: 800;
    margin-bottom: 16px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}
.footer-manifesto p {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.6;
    max-width: 360px;
}
.footer-links-grid h5 {
    font-size: 13px;
    font-weight: 700;
    color: #94a3b8;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 20px;
}
.footer-links-grid ul {
    list-style: none;
}
.footer-links-grid ul li {
    margin-bottom: 12px;
}
.footer-links-grid ul li a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 14px;
    font-weight: 500;
    transition: color 0.15s;
}
.footer-links-grid ul li a:hover {
    color: var(--brand-main);
}
.footer-meta-matrix {
    max-width: 1400px;
    margin: 0 auto;
    border-top: 1px solid var(--border-muted);
    border-bottom: 1px solid var(--border-muted);
    padding: 32px 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-family: var(--mono-font);
    font-size: 11px;
    color: #94a3b8;
    flex-wrap: wrap;
    gap: 16px;
}
.meta-status-node {
    display: flex;
    align-items: center;
    gap: 16px;
}
.meta-status-node span strong {
    color: var(--text-primary);
}
.footer-base {
    max-width: 1400px;
    margin: 0 auto;
    padding-top: 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 13px;
    color: var(--text-secondary);
}
@media (max-width: 640px) {
    .footer-base {
        flex-direction: column;
        gap: 16px;
        text-align: center;
    }
}
.footer-legal-links {
    display: flex;
    gap: 24px;
}
.footer-legal-links a {
    color: var(--text-secondary);
    text-decoration: none;
}
.footer-legal-links a:hover {
    color: var(--text-primary);
}