:root {
    /* 简洁、对比清晰的浅色主题 */
    --bg: #f3f4f6;         /* 页面背景浅灰 */
    --panel: #ffffff;      /* 卡片白色 */
    --muted: #6b7280;      /* 次要文字灰 */
    --text: #111827;       /* 主文字接近黑色 */
    --primary: #2563eb;    /* 主色：适中蓝色 */
    --primary-700: #1d4ed8;
    --accent: #0ea5e9;     /* 辅助亮蓝，用得很少 */
    --ring: rgba(37, 99, 235, 0.18);
    --radius: 14px;
    --shadow: 0 10px 28px rgba(15,23,42,0.08);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html, body {
    height: 100%;
}

body {
    font-family: 'Inter', ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, 'Helvetica Neue', Arial, 'Noto Sans', 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol', 'Noto Color Emoji', sans-serif;
    line-height: 1.65;
    color: var(--text);
    background: var(--bg);
}

.container {
    max-width: 1040px;
    margin: 0 auto;
    padding: 0 20px;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    backdrop-filter: saturate(1.1) blur(10px);
    background: rgba(249, 250, 251, 0.9);
    border-bottom: 1px solid rgba(148,163,184,0.35);
}

.brand {
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    gap: 12px;
    padding: 22px 0 10px 0;
}

.logo {
    font-weight: 800;
    font-size: 26px;
    letter-spacing: 0.2px;
    color: var(--primary-700);
}

.tagline {
    color: var(--muted);
    font-weight: 600;
    font-size: 14px;
    text-transform: uppercase;
    letter-spacing: 1.2px;
}

.toc {
    display: flex;
    flex-wrap: wrap;
    gap: 12px 16px;
    padding: 12px 0 18px 0;
}

.toc a {
    text-decoration: none;
    color: var(--text);
    background: #e5e7eb;
    padding: 10px 14px;
    border-radius: 999px;
    border: 1px solid rgba(255,255,255,0.08);
    font-weight: 600;
    font-size: 13px;
    transition: all 0.25s ease;
}

.toc span {
    color: var(--text);
    background: #e5e7eb;
    padding: 10px 14px;
    border-radius: 999px;
    border: 1px solid rgba(255,255,255,0.08);
    font-weight: 600;
    font-size: 13px;
    cursor: default;
    user-select: none;
}

.toc a:hover {
    color: #fff;
    background: var(--primary);
    border-color: var(--primary);
    box-shadow: 0 0 0 6px var(--ring);
}

.card {
    background: var(--panel);
    border: 1px solid rgba(148,163,184,0.35);
    border-radius: var(--radius);
    padding: 28px 28px;
    margin: 20px 0;
    box-shadow: var(--shadow);
}

.card h2 {
    font-size: 22px;
    line-height: 1.25;
    margin-bottom: 12px;
    color: #0f172a;
}

.kicker {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 12px;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--primary-700);
    background: #e0edff;
    border: 1px solid rgba(37,99,235,0.35);
    padding: 6px 10px;
    border-radius: 999px;
    margin-bottom: 10px;
}

.kicker i {
    font-size: 13px;
    color: var(--primary-700);
}

.card p {
    color: var(--text);
    margin-bottom: 12px;
}

.card ul {
    margin-left: 20px;
    margin-top: 8px;
}

.card li {
    margin-bottom: 8px;
}

.card .meta {
    color: var(--muted);
    font-size: 14px;
    margin-top: 8px;
}

.callout {
    background: #e0f2fe;
    border-color: rgba(37,99,235,0.5);
}

.contact-email a {
    color: var(--primary-700);
    text-decoration: none;
    font-weight: 700;
    border-bottom: 2px solid rgba(14,165,165,0.5);
    transition: all 0.2s ease;
}

.contact-email a:hover {
    color: var(--primary);
    border-bottom-color: var(--primary);
}

.contact-email {
    color: var(--primary-700);
    font-weight: 700;
    border-bottom: 2px solid rgba(37,99,235,0.4);
}

.site-footer {
    margin: 40px 0 24px 0;
    color: var(--muted);
    text-align: center;
}

@media (max-width: 768px) {
    .toc {
        gap: 8px 10px;
    }
    .toc a {
        font-size: 12px;
        padding: 8px 12px;
    }
    .toc span {
        font-size: 12px;
        padding: 8px 12px;
    }
    .card {
        padding: 22px 18px;
    }
}