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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: #f5f5f5;
    display: flex;
}

.sidebar {
    width: 250px;
    background-color: #2c3e50;
    color: white;
    padding: 20px 0;
    position: fixed;
    height: 100vh;
    overflow-y: auto;
}

.nav-header {
    padding: 0 20px 20px;
    border-bottom: 1px solid #34495e;
}

.nav-title {
    color: white;
    text-decoration: none;
    font-size: 24px;
    font-weight: bold;
    display: block;
    transition: color 0.2s;
}

.nav-title:hover {
    color: #3498db;
}

.nav-list {
    list-style: none;
    margin-top: 20px;
}

.nav-list li {
    margin: 0;
}

.nav-list li.category {
    margin: 0;
}

.category-toggle {
    width: 100%;
    padding: 12px 20px;
    background-color: transparent;
    border: none;
    color: #ecf0f1;
    cursor: pointer;
    text-align: left;
    font-family: inherit;
    font-size: 14px;
    font-weight: 500;
    transition: all 0.2s;
    border-left: 3px solid transparent;
}

.category-toggle:hover {
    background-color: #34495e;
    color: #3498db;
    border-left-color: #3498db;
}

.category-toggle.open {
    background-color: #34495e;
    border-left-color: #3498db;
}

.category-items {
    list-style: none;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.2s ease;
}

.category-items.open {
    max-height: 1000px;
}

.category-items li a {
    padding-left: 40px;
    font-size: 13px;
}

.nav-list a {
    display: block;
    padding: 12px 20px;
    color: #ecf0f1;
    text-decoration: none;
    transition: all 0.2s;
    border-left: 3px solid transparent;
}

.nav-list a:hover {
    background-color: #34495e;
    color: #3498db;
    border-left-color: #3498db;
}

.nav-list a.active {
    background-color: #3498db;
    color: white;
    border-left-color: #2980b9;
}

main {
    margin-left: 250px;
    flex: 1;
    padding: 20px;
}

.container {
    max-width: 900px;
    background-color: white;
    padding: 40px;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

h1 {
    color: #2c3e50;
    margin-bottom: 20px;
    font-size: 32px;
    border-bottom: 2px solid #3498db;
    padding-bottom: 10px;
}

h2 {
    color: #34495e;
    margin-top: 30px;
    margin-bottom: 15px;
    font-size: 24px;
}

h3 {
    color: #7f8c8d;
    margin-top: 20px;
    margin-bottom: 10px;
    font-size: 18px;
}

p {
    color: #2c3e50;
    line-height: 1.6;
    margin-bottom: 15px;
}

ul, ol {
    margin-left: 30px;
    margin-bottom: 15px;
}

li {
    margin-bottom: 8px;
    line-height: 1.6;
}

a {
    color: #3498db;
    text-decoration: none;
    transition: color 0.2s;
}

a:hover {
    color: #2980b9;
    text-decoration: underline;
}

code {
    background-color: #ecf0f1;
    padding: 2px 6px;
    border-radius: 3px;
    font-family: 'Courier New', monospace;
    color: #c0392b;
}

pre {
    background-color: #2c3e50;
    color: #ecf0f1;
    padding: 15px;
    border-radius: 5px;
    overflow-x: auto;
    margin-bottom: 15px;
    border-left: 4px solid #3498db;
}

pre code {
    background-color: transparent;
    color: #ecf0f1;
    padding: 0;
    border-radius: 0;
    font-size: 13px;
    line-height: 1.4;
}

blockquote {
    border-left: 4px solid #3498db;
    padding: 10px 0 10px 20px;
    margin: 15px 0;
    background-color: #ecf0f1;
    color: #34495e;
}

blockquote p {
    margin: 0;
}

hr {
    border: none;
    height: 2px;
    background-color: #bdc3c7;
    margin: 30px 0;
}

img {
    max-width: 100%;
    height: auto;
    border-radius: 4px;
    margin: 15px 0;
}

ol {
    margin-left: 30px;
    margin-bottom: 15px;
}

ol li {
    margin-bottom: 8px;
}

strong {
    color: #2c3e50;
    font-weight: bold;
}

em {
    font-style: italic;
    color: #34495e;
}

@media (max-width: 768px) {
    body {
        flex-direction: column;
    }

    .sidebar {
        width: 100%;
        height: auto;
        position: relative;
    }

    main {
        margin-left: 0;
    }

    .container {
        margin-top: 10px;
    }
}