:root {
    --brand: #3b82f6;
    --brand-dark: #2563eb;
    --ink: #0f172a;
    --muted: #64748b;
    --line: #e2e8f0;
    --bg: #f5f7fb;
    --card: #ffffff;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
    margin: 0;
    color: var(--ink);
    background: var(--bg);
    font-family: "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", "Microsoft YaHei", sans-serif;
    line-height: 1.75;
}

.top {
    position: sticky;
    top: 0;
    z-index: 10;
    background: rgba(255, 255, 255, 0.92);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--line);
}

.top-inner {
    max-width: 780px;
    margin: 0 auto;
    padding: 14px 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
}

.brand {
    margin: 0;
    font-family: "Snell Roundhand", "Segoe Script", cursive;
    color: var(--brand);
    font-size: 26px;
    line-height: 1;
}

.nav {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.nav a {
    text-decoration: none;
    color: var(--brand-dark);
    background: #eff6ff;
    border-radius: 999px;
    padding: 6px 12px;
    font-size: 13px;
    font-weight: 600;
}

.nav a.active {
    background: var(--brand);
    color: #fff;
}

.wrap {
    max-width: 780px;
    margin: 0 auto;
    padding: 28px 20px 64px;
}

.hero {
    background: var(--card);
    border-radius: 20px;
    padding: 28px 24px;
    box-shadow: 0 12px 32px rgba(15, 23, 42, 0.06);
    margin-bottom: 20px;
}

.hero h1 {
    margin: 0 0 8px;
    font-size: 26px;
}

.meta {
    margin: 0;
    color: var(--muted);
    font-size: 13px;
}

.lead {
    margin: 16px 0 0;
    color: #334155;
}

.toc {
    background: var(--card);
    border-radius: 16px;
    padding: 18px 22px;
    margin-bottom: 20px;
    box-shadow: 0 8px 24px rgba(15, 23, 42, 0.04);
}

.toc h2 {
    margin: 0 0 10px;
    font-size: 15px;
}

.toc ol {
    margin: 0;
    padding-left: 20px;
}

.toc a {
    color: var(--brand-dark);
    text-decoration: none;
}

.card {
    background: var(--card);
    border-radius: 16px;
    padding: 8px 24px 24px;
    box-shadow: 0 8px 24px rgba(15, 23, 42, 0.04);
}

h2 {
    margin: 28px 0 10px;
    font-size: 18px;
    padding-top: 8px;
}

h3 {
    margin: 18px 0 8px;
    font-size: 16px;
}

p, li { font-size: 15px; color: #334155; }
ul, ol { padding-left: 1.2em; }
li { margin: 4px 0; }

.table-wrap {
    overflow-x: auto;
    margin: 12px 0 4px;
}

table {
    width: 100%;
    min-width: 520px;
    border-collapse: collapse;
    font-size: 13px;
    margin: 0;
}

th, td {
    border: 1px solid var(--line);
    padding: 10px 8px;
    text-align: left;
    vertical-align: top;
}

th {
    background: #f8fafc;
    color: var(--muted);
    font-weight: 600;
}

.note {
    background: #eff6ff;
    border-radius: 12px;
    padding: 12px 14px;
    color: #1e3a8a;
    font-size: 14px;
}

footer {
    margin-top: 24px;
    color: var(--muted);
    font-size: 12px;
    text-align: center;
}

@media (max-width: 640px) {
    .hero, .card, .toc { padding-left: 16px; padding-right: 16px; }
    .hero h1 { font-size: 22px; }
}