/* ===== 蓝色变体 ===== */
:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --accent-color: #3b82f6;
    --bg-color: #eff6ff;
    --card-bg: #ffffff;
    --text-color: #1e293b;
    --text-muted: #64748b;
    --border-color: #bfdbfe;
    --hover-color: #1d4ed8;
    --header-bg: #ffffff;
    --footer-bg: #1e3a5f;
    --footer-text: #bfdbfe;
    --ad-bg: #fef3c7;
    --ad-text: #92400e;
    --shadow: 0 2px 8px rgba(37,99,235,0.1);
    --radius: 12px;
}

/* ===== 基础模板变量 - 由变体覆盖 ===== */
:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --accent-color: #3b82f6;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-color: #1e293b;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
    --hover-color: #2563eb;
    --header-bg: #ffffff;
    --footer-bg: #1e293b;
    --footer-text: #cbd5e1;
    --ad-bg: #fef3c7;
    --ad-text: #92400e;
    --shadow: 0 2px 8px rgba(0,0,0,0.08);
    --radius: 12px;
}

/* ===== Reset ===== */
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
}
a { color: var(--primary-color); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--hover-color); }

/* ===== Header ===== */
.site-header {
    background: var(--header-bg);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}
.header-inner {
    max-width: 1400px;
    margin: 0 auto;
    padding: 16px 24px;
    display: flex;
    align-items: center;
    gap: 24px;
}
.logo-area { display: flex; align-items: center; gap: 12px; }
.logo-icon { font-size: 32px; }
.site-title { font-size: 24px; font-weight: 700; color: var(--primary-color); }
.header-nav { margin-left: auto; }
.hub-link {
    padding: 8px 16px;
    background: var(--primary-color);
    color: #fff;
    border-radius: 8px;
    font-size: 14px;
}
.hub-link:hover { background: var(--secondary-color); color: #fff; }
.search-box { width: 300px; }
.search-box input {
    width: 100%;
    padding: 10px 16px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 14px;
    outline: none;
}
.search-box input:focus { border-color: var(--primary-color); }

/* ===== Ad Banner ===== */
.ad-banner {
    max-width: 1400px;
    margin: 16px auto;
    padding: 12px 24px;
    background: var(--ad-bg);
    color: var(--ad-text);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    font-size: 14px;
}
.ad-contact-btn {
    padding: 6px 16px;
    background: var(--ad-text);
    color: #fff;
    border-radius: 6px;
    font-size: 13px;
}
.ad-contact-btn:hover { opacity: 0.9; color: #fff; }

/* ===== Main Content ===== */
.main-content { padding: 24px 0; }
.content-wrapper {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 24px;
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 24px;
}

/* ===== Categories Grid ===== */
.categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(380px, 1fr));
    gap: 20px;
}
.category-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 20px;
    box-shadow: var(--shadow);
    transition: transform 0.2s, box-shadow 0.2s;
}
.category-card:hover { transform: translateY(-2px); box-shadow: 0 4px 16px rgba(0,0,0,0.12); }
.category-header {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 16px;
    padding-bottom: 12px;
    border-bottom: 2px solid var(--border-color);
}
.category-icon { font-size: 24px; }
.category-name { font-size: 18px; font-weight: 600; color: var(--text-color); }
.link-list { list-style: none; }
.link-list li { margin-bottom: 8px; }
.link-list a {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 12px;
    border-radius: 6px;
    transition: background 0.2s;
    font-size: 14px;
}
.link-list a:hover { background: var(--bg-color); }
.link-desc { color: var(--text-muted); font-size: 12px; }

/* ===== Sidebar ===== */
.sidebar {
    display: flex;
    flex-direction: column;
    gap: 16px;
    position: sticky;
    top: 80px;
    align-self: start;
}
.ad-slot {
    background: var(--card-bg);
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    padding: 24px;
    text-align: center;
    min-height: 120px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 8px;
}
.ad-slot span { color: var(--text-muted); font-size: 14px; }
.ad-slot a { font-size: 13px; color: var(--primary-color); }
.contact-card {
    background: var(--card-bg);
    border-radius: 8px;
    padding: 20px;
    box-shadow: var(--shadow);
}
.contact-card h3 { font-size: 16px; margin-bottom: 12px; color: var(--text-color); }
.contact-card p { font-size: 14px; color: var(--text-muted); margin-bottom: 8px; }

/* ===== Footer ===== */
.site-footer {
    background: var(--footer-bg);
    color: var(--footer-text);
    padding: 32px 0;
    margin-top: 48px;
}
.footer-inner {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 24px;
    text-align: center;
}
.footer-links { margin-bottom: 16px; }
.footer-links a, .footer-links span { color: var(--footer-text); margin: 0 8px; font-size: 14px; }
.footer-disclaimer { font-size: 12px; color: var(--text-muted); margin-bottom: 8px; }
.footer-copyright { font-size: 14px; }

/* ===== Back to Top ===== */
#backToTop {
    position: fixed;
    bottom: 32px;
    right: 32px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--primary-color);
    color: #fff;
    border: none;
    font-size: 20px;
    cursor: pointer;
    box-shadow: var(--shadow);
    display: none;
    z-index: 99;
}
#backToTop:hover { background: var(--secondary-color); }

/* ===== Responsive ===== */
@media (max-width: 1024px) {
    .content-wrapper { grid-template-columns: 1fr; }
    .sidebar { position: static; flex-direction: row; flex-wrap: wrap; }
    .ad-slot { flex: 1; min-width: 200px; }
}
@media (max-width: 768px) {
    .header-inner { flex-wrap: wrap; }
    .search-box { width: 100%; order: 3; }
    .categories-grid { grid-template-columns: 1fr; }
    .site-title { font-size: 20px; }
}