:root {
    --bg: #f6f7fb;
    --card: #ffffff;
    --text: #1f2937;
    --muted: #6b7280;
    --brand: #2563eb;
    --border: #e5e7eb;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
}

.site-header {
    background: var(--card);
    border-bottom: 1px solid var(--border);
}

.nav {
    max-width: 960px;
    margin: 0 auto;
    padding: 14px 20px;
    display: flex;
    gap: 22px;
    align-items: center;
}

.nav a {
    color: var(--text);
    text-decoration: none;
    font-size: 15px;
}

.nav a:hover {
    color: var(--brand);
}

.container {
    max-width: 960px;
    margin: 28px auto;
    padding: 0 20px;
}

.article,
.ad-slot {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 28px;
    margin-bottom: 20px;
}

.article h1 {
    margin-top: 0;
    font-size: 26px;
}

.download-button {
    display: inline-block;
    padding: 12px 22px;
    background: var(--brand);
    color: #fff;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
}

.download-button:hover {
    background: #1d4ed8;
}

.ad-slot {
    min-height: 120px;
}

.ad-label {
    font-size: 12px;
    color: var(--muted);
    margin: 0 0 8px;
}

.ad-note {
    color: var(--muted);
    font-size: 13px;
}

.site-footer {
    text-align: center;
    color: var(--muted);
    font-size: 13px;
    padding: 28px 20px;
}