/* ============================================================
   关于本站子页(about.html)专用样式,v74
   - 复用 css/styles.css 的主题变量与 .btn
   - ⚠️ styles.css 里 html,body 是 height:100% + overflow:hidden(SPA 布局),
     本页必须显式放开滚动,否则整页无法滚动(与 feedback.css 同一处理)。
   - 全站约定:不用 emoji,图标一律内联 SVG;颜色只走主题变量。
   ============================================================ */

html.ab-html {
    height: auto;
    overflow-x: hidden;
    overflow-y: auto;
}

html.ab-html body {
    height: auto;
    overflow: visible;
    background:
        radial-gradient(900px 420px at 85% -10%, var(--accent-light), transparent 60%),
        var(--bg-primary);
    min-height: 100vh;
}

.ab-wrap {
    width: 100%;
    max-width: 960px;
    margin: 0 auto;
    padding: 28px 20px 72px;
    box-sizing: border-box;
}

/* ---------- 顶部 ---------- */
.ab-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 24px;
    flex-wrap: wrap;
}

.ab-brand {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 17px;
    font-weight: 600;
    color: var(--text-primary);
}

.ab-brand-mark {
    width: 34px;
    height: 34px;
    border-radius: 10px;
    background: linear-gradient(135deg, var(--accent), var(--accent-hover));
    display: inline-flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    flex: 0 0 auto;
}

.ab-brand-mark svg { width: 18px; height: 18px; display: block; }

.ab-header-spacer { flex: 1 1 auto; }

.ab-nav-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 13px;
    color: var(--text-secondary);
    text-decoration: none;
    padding: 7px 12px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-secondary);
    transition: color var(--transition), border-color var(--transition);
}

.ab-nav-link:hover { color: var(--text-primary); border-color: var(--border-light); }
.ab-nav-link svg { width: 14px; height: 14px; }

/* ---------- 头图 ---------- */
.ab-hero { margin-bottom: 26px; }

.ab-title {
    font-size: 26px;
    font-weight: 700;
    margin: 0 0 8px;
    color: var(--text-primary);
}

.ab-sub {
    margin: 0 0 14px;
    font-size: 14px;
    line-height: 1.75;
    color: var(--text-secondary);
    max-width: 66ch;
}

.ab-meta {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
    font-size: 12px;
    color: var(--text-muted);
}

.ab-chip {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 4px 10px;
    border-radius: 999px;
    border: 1px solid var(--border-color);
    background: var(--bg-tertiary);
    color: var(--text-secondary);
}

.ab-chip b { color: var(--text-primary); font-weight: 600; }

/* ---------- 两栏:目录 + 正文 ---------- */
.ab-layout { display: block; }

.ab-toc {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 14px 16px;
    margin-bottom: 20px;
}

.ab-toc h2 {
    font-size: 12px;
    font-weight: 600;
    letter-spacing: 0.04em;
    color: var(--text-muted);
    margin: 0 0 10px;
    text-transform: uppercase;
}

.ab-toc ol {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.ab-toc a {
    display: inline-block;
    font-size: 13px;
    color: var(--text-secondary);
    text-decoration: none;
    padding: 5px 10px;
    border-radius: var(--radius-sm);
    border: 1px solid transparent;
    transition: all var(--transition);
}

.ab-toc a:hover { color: var(--text-primary); background: var(--bg-hover); }

.ab-toc a.is-active {
    color: var(--text-primary);
    background: var(--accent-light);
    border-color: var(--accent);
    font-weight: 600;
}

@media (min-width: 900px) {
    .ab-layout {
        display: grid;
        grid-template-columns: 196px minmax(0, 1fr);
        gap: 26px;
        align-items: start;
    }

    .ab-toc {
        position: sticky;
        top: 20px;
        margin-bottom: 0;
    }

    .ab-toc ol { display: block; }

    .ab-toc li { margin-bottom: 2px; }

    .ab-toc a { display: block; }
}

/* ---------- 章节 ---------- */
.ab-section {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 22px;
    margin-bottom: 18px;
    box-shadow: var(--shadow-sm);
    scroll-margin-top: 16px;
}

.ab-section > h2 {
    display: flex;
    align-items: center;
    gap: 9px;
    font-size: 17px;
    font-weight: 650;
    margin: 0 0 14px;
    color: var(--text-primary);
}

.ab-section > h2 svg { width: 18px; height: 18px; color: var(--accent); flex: 0 0 auto; }

.ab-prose p {
    margin: 0 0 12px;
    font-size: 13.5px;
    line-height: 1.85;
    color: var(--text-secondary);
}

.ab-prose p:last-child { margin-bottom: 0; }

/* ---------- 功能卡片 ---------- */
.ab-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(238px, 1fr));
    gap: 12px;
}

.ab-card {
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-tertiary);
    padding: 14px;
}

.ab-card-head {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 7px;
}

.ab-card-head svg { width: 16px; height: 16px; color: var(--accent); flex: 0 0 auto; }

.ab-card-head h3 {
    font-size: 13.5px;
    font-weight: 600;
    margin: 0;
    color: var(--text-primary);
}

.ab-card p {
    margin: 0;
    font-size: 12.5px;
    line-height: 1.7;
    color: var(--text-secondary);
}

/* ---------- 条目清单(数据来源口径) ---------- */
.ab-list {
    list-style: none;
    margin: 0;
    padding: 0;
}

.ab-list li {
    position: relative;
    padding: 9px 0 9px 16px;
    font-size: 13px;
    line-height: 1.8;
    color: var(--text-secondary);
    border-bottom: 1px dashed var(--border-color);
}

.ab-list li:last-child { border-bottom: none; padding-bottom: 0; }

.ab-list li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 17px;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--accent);
    opacity: 0.75;
}

/* ---------- 用户须知(带左侧警示条) ---------- */
.ab-note {
    border-left: 3px solid var(--accent);
    background: var(--bg-tertiary);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    padding: 12px 14px;
    margin-bottom: 10px;
}

.ab-note:last-child { margin-bottom: 0; }

.ab-note h3 {
    font-size: 13.5px;
    font-weight: 600;
    margin: 0 0 5px;
    color: var(--text-primary);
}

.ab-note p {
    margin: 0;
    font-size: 12.5px;
    line-height: 1.75;
    color: var(--text-secondary);
}

.ab-note.is-warn { border-left-color: var(--warning); }
.ab-note.is-danger { border-left-color: var(--danger); }
.ab-note.is-ok { border-left-color: var(--success); }

/* ---------- 页脚 ---------- */
.ab-footer {
    margin-top: 24px;
    padding-top: 18px;
    border-top: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: 12px;
    flex-wrap: wrap;
    font-size: 12px;
    color: var(--text-muted);
}

.ab-footer .ab-header-spacer { flex: 1 1 auto; }

.ab-footer a {
    color: var(--accent);
    text-decoration: none;
    font-weight: 600;
}

.ab-footer a:hover { text-decoration: underline; }

/* ---------- 窄屏 ---------- */
@media (max-width: 640px) {
    .ab-wrap { padding: 18px 12px 56px; }
    .ab-section { padding: 16px; border-radius: var(--radius-md); }
    .ab-title { font-size: 21px; }
    .ab-grid { grid-template-columns: 1fr; }
}

@media (prefers-reduced-motion: reduce) {
    .ab-nav-link,
    .ab-toc a { transition: none; }
}

@media print {
    html.ab-html body { background: #fff; }
    .ab-toc, .ab-header .ab-nav-link, .ab-footer .ab-nav-link { display: none !important; }
    .ab-section { box-shadow: none; border-color: #ccc; page-break-inside: avoid; }
    html.ab-html { overflow: visible; height: auto; }
}