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

body {
    font-family: Arial, Helvetica, sans-serif;
    font-size: 14px;
    line-height: 1.6;
    color: #333;
    background: #fff;
}

.top-bar {
    background: #36c;
    color: #fff;
    padding: 10px 20px;
    display: flex;
    align-items: center;
    gap: 10px;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    height: 50px;
}

.top-bar .site-logo {
    width: 32px;
    height: 32px;
    vertical-align: middle;
}

.top-bar .site-title {
    font-size: 18px;
    font-weight: bold;
    color: #fff;
    text-decoration: none;
}

.wrapper {
    display: flex;
    margin-top: 50px;
    min-height: calc(100vh - 50px);
}

.sidebar {
    width: 260px;
    background: #f5f5f5;
    border-right: 1px solid #ddd;
    padding: 20px 0;
    position: fixed;
    top: 50px;
    left: 0;
    bottom: 0;
    overflow-y: auto;
}

.sidebar .nav-header {
    padding: 0 16px 12px;
    font-size: 13px;
    font-weight: bold;
    color: #666;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    border-bottom: 1px solid #ddd;
    margin-bottom: 8px;
}

.sidebar .nav-menu {
    list-style: none;
}

.sidebar .nav-item {
    margin: 0;
}

.sidebar .nav-link {
    display: block;
    padding: 8px 16px;
    color: #333;
    text-decoration: none;
    font-size: 13px;
    border-left: 3px solid transparent;
}

.sidebar .nav-link:hover {
    background: #e8e8e8;
    border-left-color: #36c;
}

.sidebar .nav-link.active {
    background: #e0e8f0;
    border-left-color: #36c;
    font-weight: bold;
    color: #1a3a6e;
}

.sidebar .nav-link.sub-link {
    padding-left: 32px;
    font-size: 12px;
    color: #555;
}

.main-content {
    margin-left: 260px;
    flex: 1;
    padding: 30px 40px;
    max-width: 960px;
}

.content-card {
    background: #fff;
}

.content-card h1 {
    font-size: 28px;
    font-weight: normal;
    color: #1a3a6e;
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 1px solid #eee;
}

.content-card h2 {
    font-size: 20px;
    font-weight: bold;
    color: #36c;
    margin: 24px 0 12px;
}

.content-card h3 {
    font-size: 16px;
    font-weight: bold;
    color: #444;
    margin: 20px 0 10px;
}

.content-card p {
    margin-bottom: 14px;
}

.content-card ul, .content-card ol {
    margin: 10px 0 14px 24px;
}

.content-card li {
    margin-bottom: 6px;
}

.content-card a {
    color: #1a5e9c;
    text-decoration: underline;
}

.content-card a:hover {
    color: #36c;
}

.content-card img.content-img {
    max-width: 100%;
    height: auto;
    margin: 10px 0;
}

.content-card img.inline-img {
    vertical-align: middle;
    margin-right: 6px;
}

.content-card hr {
    border: none;
    border-top: 1px solid #ddd;
    margin: 24px 0;
}

.content-card .footer-book {
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px solid #eee;
    font-size: 13px;
    color: #666;
}

.content-card .footer-book h3 {
    font-size: 14px;
    color: #555;
    margin-bottom: 8px;
}

.content-card .footer-book ol {
    margin: 8px 0 8px 20px;
}

.content-card .footer-book ol li {
    margin-bottom: 3px;
}

.content-card .icon-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
}

@media (max-width: 768px) {
    .sidebar {
        width: 200px;
    }
    .main-content {
        margin-left: 200px;
        padding: 20px;
    }
}