:root {
    --color-bg: #ffffff;
    --color-text: #1a1a1a;
    --color-border: #e0e0e0;
    --color-accent: #0066cc;
    --color-hover: #f5f5f5;
    --color-sidebar-bg: #fafafa;
}

[data-theme="dark"] {
    --color-bg: #1a1a1a;
    --color-text: #ffffff;
    --color-border: #333333;
    --color-accent: #4da6ff;
    --color-hover: #2a2a2a;
    --color-sidebar-bg: #242424;
}

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

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

/* Header */
.header {
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    max-width: 1400px;
    margin: 0 auto;
}

.header-right {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.site-title {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--color-accent);
    text-decoration: none;
    transition: opacity 0.2s;
}

.site-title:hover {
    opacity: 0.8;
}

.header-link {
    color: var(--color-text);
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 500;
    padding: 0.4rem 0.75rem;
    border-radius: 0.3rem;
    transition: all 0.2s;
}

.header-link:hover {
    color: var(--color-accent);
    background-color: var(--color-hover);
}

/* Mobile menu toggle */
.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    width: 40px;
    height: 40px;
    align-items: center;
    justify-content: center;
}

.menu-icon,
.menu-icon::before,
.menu-icon::after {
    display: block;
    width: 22px;
    height: 2px;
    background-color: var(--color-text);
    transition: transform 0.3s;
    position: relative;
}

.menu-icon::before,
.menu-icon::after {
    content: '';
    position: absolute;
    left: 0;
}

.menu-icon::before { top: -7px; }
.menu-icon::after { top: 7px; }

.theme-toggle {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.5rem;
    color: var(--color-text);
}

/* Layout */
.container {
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: 2rem;
    max-width: 1400px;
    margin: 0 auto;
    padding: 2rem;
    min-height: calc(100vh - 70px);
}

/* Sidebar Navigation */
.sidebar {
    background-color: var(--color-sidebar-bg);
    padding: 1.5rem;
    border-radius: 0.5rem;
    height: fit-content;
    position: sticky;
    top: 90px;
    max-height: calc(100vh - 120px);
    overflow-y: auto;
}

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

.nav-menu h3 {
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 1rem;
    text-transform: uppercase;
    color: var(--color-text);
}

.nav-section {
    margin-bottom: 0.5rem;
}

.nav-link {
    display: block;
    padding: 0.75rem 1rem;
    color: var(--color-text);
    text-decoration: none;
    transition: all 0.2s;
    border-radius: 0.3rem;
    font-size: 0.95rem;
}

.nav-link:hover {
    background-color: var(--color-hover);
    color: var(--color-accent);
}

/* Parent header: clickable parent link + small toggle */
.parent-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.parent-link {
    display: block;
    padding: 0.75rem 1rem;
    color: var(--color-text);
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 500;
    border-radius: 0.3rem;
}

.parent-link:hover {
    background-color: var(--color-hover);
    color: var(--color-accent);
}

.parent-link.active {
    background-color: var(--color-hover);
    color: var(--color-accent);
}

.section-toggle {
    background: none;
    border: none;
    color: var(--color-text);
    cursor: pointer;
    padding: 0.5rem 0.75rem;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: 0.3rem;
}

.section-toggle .arrow {
    font-size: 0.7rem;
    transition: transform 0.2s;
}

.section-toggle.active .arrow {
    transform: rotate(180deg);
}

.nav-subsection {
    display: none;
    padding-left: 0.5rem;
    border-left: 2px solid var(--color-border);
    margin-left: 0.5rem;
}

.nav-subsection.active {
    display: block;
}

.nav-sublink {
    display: block;
    padding: 0.5rem 1rem;
    color: var(--color-text);
    text-decoration: none;
    font-size: 0.9rem;
    transition: all 0.2s;
    border-radius: 0.3rem;
    margin-bottom: 0.25rem;
}

.nav-sublink:hover {
    background-color: var(--color-hover);
    color: var(--color-accent);
}

/* Table of Contents */
.toc-container h3 {
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 1rem;
    text-transform: uppercase;
    color: var(--color-text);
}

.toc {
    font-size: 0.9rem;
}

.toc ul {
    list-style: none;
    margin-left: 0;
}

.toc li {
    margin: 0.5rem 0;
}

.toc a {
    color: var(--color-text);
    text-decoration: none;
    transition: color 0.2s;
    display: block;
    padding: 0.25rem 0;
    border-left: 2px solid transparent;
    padding-left: 0.75rem;
    font-size: 0.9rem;
}

.toc a:hover,
.toc a.active {
    color: var(--color-accent);
    border-left-color: var(--color-accent);
}

/* Content */
.content {
    min-height: 100vh;
}

.content h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    margin-top: 0;
}

.content h2 {
    font-size: 2rem;
    margin-top: 2rem;
    margin-bottom: 0.75rem;
    border-bottom: 1px solid var(--color-border);
    padding-bottom: 0.5rem;
}

.content h3 {
    font-size: 1.5rem;
    margin-top: 1.5rem;
    margin-bottom: 0.5rem;
}

.content p {
    margin-bottom: 1rem;
}

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

.content a:hover {
    text-decoration: underline;
}

.content code {
    background-color: var(--color-hover);
    padding: 0.2rem 0.5rem;
    border-radius: 0.25rem;
    font-family: "Monaco", "Courier New", monospace;
    font-size: 0.9em;
}

.content pre {
    background-color: var(--color-sidebar-bg);
    padding: 1.5rem;
    border-radius: 0.5rem;
    overflow-x: auto;
    margin: 1rem 0;
    border-left: 4px solid var(--color-accent);
    position: relative;
}

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

.copy-button {
    position: absolute;
    top: 0.75rem;
    right: 0.75rem;
    background-color: var(--color-accent);
    color: var(--color-bg);
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 0.3rem;
    cursor: pointer;
    font-size: 0.85rem;
    font-weight: 500;
    transition: all 0.2s;
    opacity: 0;
}

.content pre:hover .copy-button {
    opacity: 1;
}

.copy-button:hover {
    background-color: var(--color-text);
    transform: scale(1.05);
}

.copy-button.copied {
    background-color: #10b981;
}

.content ul,
.content ol {
    margin-left: 2rem;
    margin-bottom: 1rem;
}

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

.content blockquote {
    border-left: 4px solid var(--color-accent);
    padding-left: 1rem;
    margin: 1rem 0;
    color: var(--color-text);
    opacity: 0.8;
}

.content table {
    width: 100%;
    border-collapse: collapse;
    margin: 1rem 0;
}

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

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

/* Responsive */
@media (max-width: 1024px) {
    .container {
        grid-template-columns: 250px 1fr;
        gap: 1.5rem;
        padding: 1.5rem;
    }
}

@media (max-width: 768px) {
    .mobile-menu-toggle {
        display: inline-flex;
    }

    .container {
        grid-template-columns: 1fr;
    }

    .sidebar {
        display: none;
        position: fixed;
        top: 60px;
        left: 0;
        right: 0;
        bottom: 0;
        z-index: 99;
        max-height: none;
        border-radius: 0;
        overflow-y: auto;
        margin: 0;
        padding: 1.5rem;
    }

    .sidebar.mobile-open {
        display: block;
    }

    .header-content {
        padding: 1rem;
    }

    .content h1 {
        font-size: 1.75rem;
    }

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

    .content h3 {
        font-size: 1.25rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 1rem;
        gap: 1rem;
    }

    .sidebar {
        padding: 1rem;
    }

    .content h1 {
        font-size: 1.5rem;
    }

    .content h2 {
        font-size: 1.25rem;
    }
}

/* Footer */
.site-footer {
    border-top: 1px solid var(--color-border);
    padding: 2rem;
    text-align: center;
    color: var(--color-text);
    opacity: 0.6;
    font-size: 0.9rem;
}

.site-footer a {
    color: var(--color-accent);
    text-decoration: none;
}

.site-footer a:hover {
    text-decoration: underline;
}

/* Active nav states */
.nav-link.active,
.nav-sublink.active {
    color: var(--color-accent);
    background-color: var(--color-hover);
    font-weight: 600;
}

/* Page Metadata and Tags */
.page-meta {
    margin-bottom: 1.5rem;
    padding: 1rem;
    background-color: var(--color-hover);
    border-left: 4px solid var(--color-accent);
    border-radius: 0.25rem;
}

.page-meta .description {
    margin: 0;
    font-style: italic;
    color: var(--color-text);
    opacity: 0.85;
}

.page-tags {
    margin-bottom: 1.5rem;
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.tag {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background-color: var(--color-accent);
    color: white;
    border-radius: 1rem;
    font-size: 0.875rem;
    font-weight: 500;
}