:root {
    --bg: #f4f7fb;
    --card: #ffffff;
    --primary: #1f4b8f;
    --accent: #e34d5b;
    --text: #334155;
    --muted: #64748b;
    --border: #e2e8f0;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    padding: 32px 24px 48px;
    font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
    line-height: 1.7;
    color: var(--text);
    background: linear-gradient(135deg, #f8fbff 0%, #eef4ff 100%);
}

h1 {
    font-size: clamp(2rem, 4vw, 3.2rem);
    color: var(--primary);
    margin: 0 0 24px;
    text-align: center;
    font-weight: 700;
    letter-spacing: 0.02em;
}

h2 {
    font-size: clamp(1.4rem, 2.3vw, 1.9rem);
    color: var(--primary);
    margin: 0 0 16px;
    padding-bottom: 8px;
    border-bottom: 2px solid #dbeafe;
}

h3 {
    font-size: 1.15rem;
    color: var(--accent);
    margin: 20px 0 8px;
}

p {
    font-size: 1.05rem;
    color: var(--text);
    margin: 0 0 12px;
}

a {
    color: var(--primary);
    text-decoration: none;
    transition: color 0.2s ease;
}

a:hover {
    color: var(--accent);
}

body > div {
    max-width: 1100px;
    margin: 0 auto 24px;
    padding: 20px 24px;
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 18px;
    box-shadow: 0 10px 24px rgba(15, 23, 42, 0.06);
}

body > div:first-of-type {
    background: linear-gradient(135deg, #ffffff 0%, #eef6ff 100%);
}

body > div:first-of-type h2 {
    border-bottom: none;
    padding-bottom: 0;
}

body > div:first-of-type ol,
body > div:first-of-type ul {
    font-size: 1rem;
    color: var(--text);
    padding-left: 24px;
}

body > div:first-of-type ol li,
body > div:first-of-type ul li {
    margin-bottom: 10px;
}

body > div:first-of-type a {
    display: inline-block;
    padding: 6px 10px;
    border-radius: 8px;
    color: var(--primary);
    font-weight: 600;
    transition: background-color 0.2s ease, color 0.2s ease, transform 0.2s ease;
}

body > div:first-of-type a:hover {
    background-color: #e8f1ff;
    color: var(--accent);
    transform: translateX(2px);
}

iframe {
    width: 100%;
    max-width: 100%;
    min-height: 720px;
    border: 1px solid var(--border);
    border-radius: 12px;
    background: #fff;
    box-shadow: inset 0 0 0 1px rgba(0, 0, 0, 0.02);
}

@media (max-width: 768px) {
    body {
        padding: 24px 16px 60px;
    }

    body > div {
        padding: 18px;
    }

    iframe {
        min-height: 480px;
    }
}