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

:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-sidebar: #f1f3f5;
    --text-primary: #212529;
    --text-secondary: #495057;
    --border-color: #dee2e6;
    --link-color: #0066cc;
    --link-hover: #0052a3;
    --header-bg: #ffffff;
    --code-bg: #f8f9fa;
    --shadow: 0 1px 3px rgba(0,0,0,0.1);
}

body.dark-mode {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2a2a2a;
    --bg-sidebar: #252525;
    --text-primary: #e0e0e0;
    --text-secondary: #b0b0b0;
    --border-color: #404040;
    --link-color: #66b3ff;
    --link-hover: #4da3ff;
    --header-bg: #2a2a2a;
    --code-bg: #2d2d2d;
    --shadow: 0 1px 3px rgba(0,0,0,0.3);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* Header Styles */
header {
    background-color: var(--header-bg);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 2rem;
    position: sticky;
    top: 0;
    z-index: 100;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--shadow);
}

.header-left {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.header-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

.header-controls {
    display: flex;
    gap: 1rem;
    align-items: center;
}

.lang-toggle, .theme-toggle {
    background: none;
    border: 1px solid var(--border-color);
    padding: 0.5rem 1rem;
    border-radius: 0.25rem;
    cursor: pointer;
    color: var(--text-primary);
    font-size: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.3s ease;
}

.lang-toggle:hover, .theme-toggle:hover {
    background-color: var(--bg-secondary);
    transform: translateY(-1px);
    box-shadow: var(--shadow);
}

/* Hamburger Menu */
.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    background: none;
    border: none;
    padding: 0.5rem;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background-color: var(--text-primary);
    margin: 3px 0;
    transition: 0.3s;
}

.hamburger.active span:nth-child(1) {
    transform: rotate(-45deg) translate(-5px, 6px);
}

.hamburger.active span:nth-child(2) {
    opacity: 0;
}

.hamburger.active span:nth-child(3) {
    transform: rotate(45deg) translate(-5px, -6px);
}

/* Container Layout */
.container {
    display: flex;
    min-height: calc(100vh - 60px);
}

/* Sidebar Styles */
.sidebar {
    width: 300px;
    background-color: var(--bg-sidebar);
    border-right: 1px solid var(--border-color);
    padding: 2rem 1rem;
    overflow-y: auto;
    overflow-x: hidden;
    position: sticky;
    top: 60px;
    height: calc(100vh - 60px);
    scrollbar-width: thin;
    scrollbar-color: var(--border-color) transparent;
}

.sidebar::-webkit-scrollbar {
    width: 6px;
}

.sidebar::-webkit-scrollbar-track {
    background: transparent;
}

.sidebar::-webkit-scrollbar-thumb {
    background-color: var(--border-color);
    border-radius: 3px;
}

.nav-section {
    margin-bottom: 2rem;
}

.nav-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 0.25rem;
    transition: background-color 0.2s ease;
}

.nav-title:hover {
    background-color: var(--bg-secondary);
}

.nav-section-toggle {
    width: 20px;
    height: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: transform 0.2s ease;
}

.nav-section-toggle::after {
    content: '▼';
    font-size: 0.6rem;
    color: var(--text-secondary);
}

.nav-section.collapsed .nav-section-toggle::after {
    transform: rotate(-90deg);
}

.nav-list {
    list-style: none;
    transition: all 0.3s ease-out;
}

.nav-section.collapsed .nav-list {
    height: 0;
    overflow: hidden;
    opacity: 0;
}

.nav-item {
    margin-bottom: 0.25rem;
    position: relative;
}

.nav-item.has-subitems > .nav-link {
    position: relative;
    padding-right: 2.5rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.nav-link {
    display: block;
    padding: 0.5rem 1rem;
    color: var(--text-secondary);
    text-decoration: none;
    border-radius: 0.25rem;
    transition: all 0.2s ease;
}

.nav-toggle {
    position: absolute;
    right: 0.5rem;
    top: 50%;
    transform: translateY(-50%);
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: transform 0.2s ease;
}

.nav-toggle::after {
    content: '▶';
    font-size: 0.7rem;
    color: var(--text-secondary);
}

.nav-item.expanded .nav-toggle::after {
    transform: rotate(90deg);
}

.nav-link:hover {
    background-color: var(--bg-secondary);
    color: var(--link-color);
    transform: translateX(2px);
}

.nav-link.active {
    background-color: var(--bg-secondary);
    color: var(--link-color);
    font-weight: 500;
}

.nav-sublist {
    list-style: none;
    margin-left: 1rem;
    margin-top: 0.25rem;
    height: 0;
    overflow: hidden;
    opacity: 0;
    transition: all 0.3s ease-out;
}

.nav-item.expanded .nav-sublist {
    height: auto;
    overflow: visible;
    opacity: 1;
    transition: all 0.3s ease-in;
}

.nav-sublink {
    display: block;
    padding: 0.4rem 1rem 0.4rem 2rem;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    transition: all 0.2s ease;
    white-space: normal;
    word-wrap: break-word;
}

.nav-sublink:hover {
    color: var(--link-color);
    background-color: var(--bg-secondary);
}

.nav-link.external-link {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-link.external-link:hover {
    background-color: var(--bg-secondary);
    color: var(--link-color);
    transform: translateX(2px);
}

/* Content Styles */
.content {
    flex: 1;
    padding: 2rem 3rem;
    max-width: 900px;
    margin: 0 auto;
}

.loading {
    text-align: center;
    padding: 4rem;
    color: var(--text-secondary);
}

/* Typography */
.content h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0.5rem;
}

.content h2 {
    font-size: 2rem;
    margin-top: 2rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.content h3 {
    font-size: 1.5rem;
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.content h4 {
    font-size: 1.25rem;
    margin-top: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.content h5 {
    font-size: 1.1rem;
    margin-top: 1rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.content h6 {
    font-size: 1rem;
    margin-top: 1rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.content p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

.content blockquote {
    border-left: 4px solid var(--link-color);
    padding-left: 1rem;
    margin: 1rem 0;
    color: var(--text-secondary);
    font-style: italic;
    background-color: var(--bg-secondary);
    padding: 1rem;
    border-radius: 0 0.25rem 0.25rem 0;
}

.content code {
    background-color: var(--code-bg);
    padding: 0.2rem 0.4rem;
    border-radius: 3px;
    font-family: 'Courier New', monospace;
    font-size: 0.9em;
}

.content pre {
    background-color: var(--code-bg);
    padding: 1rem;
    border-radius: 5px;
    overflow-x: auto;
    margin-bottom: 1rem;
    border: 1px solid var(--border-color);
}

.content pre code {
    background: none;
    padding: 0;
}

.content ul, .content ol {
    margin-bottom: 1rem;
    padding-left: 2rem;
    color: var(--text-secondary);
}

.content li {
    margin-bottom: 0.5rem;
}

.content a {
    color: var(--link-color);
    text-decoration: none;
}

.content a:hover {
    color: var(--link-hover);
    text-decoration: underline;
}

.content table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 1rem;
    overflow-x: auto;
    display: block;
}

.content th, .content td {
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    text-align: left;
}

.content th {
    background-color: var(--bg-secondary);
    font-weight: 600;
}

.content tr:hover {
    background-color: var(--bg-secondary);
}

/* Responsive Design */
@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }

    .sidebar {
        position: fixed;
        left: -300px;
        top: 60px;
        transition: left 0.3s ease;
        z-index: 99;
        box-shadow: 2px 0 10px rgba(0, 0, 0, 0.1);
    }

    .sidebar.active {
        left: 0;
    }

    .content {
        padding: 1rem;
    }

    header {
        padding: 1rem;
    }

    .header-title {
        font-size: 1.2rem;
    }

    .lang-toggle span:last-child,
    .theme-toggle span:last-child {
        display: none;
    }

    .content h1 {
        font-size: 2rem;
    }

    .content h2 {
        font-size: 1.5rem;
    }

    .content h3 {
        font-size: 1.25rem;
    }
    
    .nav-toggle {
        width: 32px;
        height: 32px;
    }
}

/* Utilities */
.hidden {
    display: none !important;
}

/* Mermaid Diagrams */
.mermaid {
    margin: 1rem 0;
    text-align: center;
}

/* Animations */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in {
    animation: fadeIn 0.3s ease-out;
}