:root {
    --primary: #4f46e5;
    --primary-dark: #3730a3;
    --ink: #172033;
    --muted: #5f6b7a;
    --surface: #ffffff;
    --soft: #f5f7fb;
    --border: #dfe5ee;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    color: var(--ink);
    background: var(--soft);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Microsoft YaHei", sans-serif;
    line-height: 1.75;
}

a { color: var(--primary-dark); }

.site-nav {
    position: sticky;
    top: 0;
    z-index: 20;
    border-bottom: 1px solid rgba(223, 229, 238, 0.9);
    background: rgba(255, 255, 255, 0.94);
    backdrop-filter: blur(12px);
}

.site-nav-inner {
    width: min(1120px, calc(100% - 32px));
    margin: 0 auto;
    min-height: 64px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
}

.brand {
    color: var(--ink);
    text-decoration: none;
    font-weight: 800;
}

.nav-links { display: flex; gap: 18px; flex-wrap: wrap; }
.nav-links a { color: var(--muted); text-decoration: none; font-size: 14px; }
.nav-links a:hover { color: var(--primary); }

.page-shell {
    width: min(960px, calc(100% - 32px));
    margin: 0 auto;
    padding: 48px 0 72px;
}

.breadcrumbs {
    color: var(--muted);
    font-size: 14px;
    margin-bottom: 24px;
}

.breadcrumbs a { color: inherit; }

.hero-card,
.content-card,
.guide-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 18px;
    box-shadow: 0 12px 32px rgba(35, 48, 75, 0.06);
}

.hero-card { padding: clamp(28px, 6vw, 56px); }

.eyebrow {
    color: var(--primary);
    font-size: 13px;
    font-weight: 750;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

h1 {
    margin: 10px 0 16px;
    font-size: clamp(32px, 6vw, 52px);
    line-height: 1.18;
    letter-spacing: -0.03em;
}

h2 {
    margin: 0 0 14px;
    font-size: clamp(22px, 4vw, 30px);
    line-height: 1.35;
}

h3 { margin: 0 0 10px; line-height: 1.4; }

.lede {
    max-width: 800px;
    margin: 0;
    color: var(--muted);
    font-size: 18px;
}

.answer-box {
    margin-top: 24px;
    padding: 20px 22px;
    border-left: 4px solid var(--primary);
    border-radius: 0 12px 12px 0;
    background: #eef2ff;
}

.meta-row {
    display: flex;
    flex-wrap: wrap;
    gap: 10px 20px;
    margin-top: 22px;
    color: var(--muted);
    font-size: 14px;
}

.content-card { margin-top: 24px; padding: clamp(24px, 5vw, 42px); }
.content-card p:last-child, .content-card ul:last-child { margin-bottom: 0; }
.content-card li + li { margin-top: 8px; }

.guide-grid,
.related-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 18px;
    margin-top: 24px;
}

.guide-card { padding: 24px; }
.guide-card p { color: var(--muted); }
.guide-card a { font-weight: 700; text-decoration: none; }

.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; min-width: 620px; }
th, td { padding: 14px; border-bottom: 1px solid var(--border); text-align: left; vertical-align: top; }
th { background: var(--soft); font-size: 14px; }

.faq-item + .faq-item { border-top: 1px solid var(--border); margin-top: 18px; padding-top: 18px; }
.faq-item p { margin-bottom: 0; color: var(--muted); }

.site-footer {
    padding: 26px 16px;
    color: var(--muted);
    text-align: center;
    border-top: 1px solid var(--border);
    background: var(--surface);
}

@media (max-width: 720px) {
    .site-nav-inner { align-items: flex-start; flex-direction: column; padding: 14px 0; gap: 8px; }
    .guide-grid, .related-grid { grid-template-columns: 1fr; }
    .page-shell { padding-top: 28px; }
}