:root {
    --bg: #0d1117;
    --bg-secondary: #161b22;
    --bg-tertiary: #21262d;
    --text: #e6edf3;
    --text-secondary: #8b949e;
    --accent: #58a6ff;
    --border: #30363d;
    --success: #3fb950;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans SC', sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
}

.container {
    display: flex;
    min-height: 100vh;
}

/* Sidebar */
.sidebar {
    width: 260px;
    background: var(--bg-secondary);
    border-right: 1px solid var(--border);
    padding: 1.5rem;
    position: fixed;
    height: 100vh;
    overflow-y: auto;
}

.sidebar h1 {
    font-size: 1.3rem;
    margin-bottom: 0.5rem;
}

.sidebar .subtitle {
    color: var(--text-secondary);
    font-size: 0.85rem;
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border);
}

.nav-section {
    margin-bottom: 1.5rem;
}

.nav-section h2 {
    font-size: 0.7rem;
    text-transform: uppercase;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    letter-spacing: 0.05em;
}

.nav-section ul {
    list-style: none;
}

.nav-section a {
    display: block;
    padding: 0.35rem 0.5rem;
    color: var(--text);
    text-decoration: none;
    border-radius: 4px;
    font-size: 0.85rem;
    transition: background 0.15s;
}

.nav-section a:hover {
    background: var(--bg-tertiary);
}

.nav-section a.active {
    background: var(--accent);
    color: #000;
}

/* Main Content */
.main {
    margin-left: 260px;
    flex: 1;
    padding: 2rem 3rem;
    max-width: 850px;
}

.content h1 {
    font-size: 1.8rem;
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border);
}

.content h2 {
    font-size: 1.3rem;
    margin: 2rem 0 1rem;
    padding-bottom: 0.3rem;
    border-bottom: 1px solid var(--border);
}

.content h3 {
    font-size: 1.05rem;
    margin: 1.5rem 0 0.75rem;
    color: var(--accent);
}

.content p {
    margin: 0.75rem 0;
}

.content ul, .content ol {
    margin: 0.75rem 0 0.75rem 1.5rem;
}

.content li {
    margin: 0.4rem 0;
}

.content blockquote {
    border-left: 3px solid var(--accent);
    padding-left: 1rem;
    margin: 1rem 0;
    color: var(--text-secondary);
    font-style: italic;
}

.content code {
    background: var(--bg-tertiary);
    padding: 0.15rem 0.35rem;
    border-radius: 4px;
    font-size: 0.9em;
    font-family: 'SF Mono', Consolas, monospace;
}

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

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

.content hr {
    border: none;
    border-top: 1px solid var(--border);
    margin: 2rem 0;
}

.content strong {
    color: #fff;
}

/* Cards */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 1rem;
    margin: 1rem 0;
}

.card {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 1rem;
    transition: border-color 0.15s;
}

.card:hover {
    border-color: var(--accent);
}

.card h3 {
    margin: 0 0 0.5rem;
    font-size: 1rem;
    color: var(--text);
}

.card p {
    color: var(--text-secondary);
    font-size: 0.85rem;
    margin: 0.3rem 0;
}

.card a {
    color: inherit;
    text-decoration: none;
}

.badge {
    display: inline-block;
    padding: 0.1rem 0.4rem;
    background: var(--bg-tertiary);
    border-radius: 4px;
    font-size: 0.7rem;
    color: var(--text-secondary);
    margin-right: 0.25rem;
}

.badge.green { background: #238636; color: #fff; }

/* Responsive */
@media (max-width: 768px) {
    .sidebar {
        position: static;
        width: 100%;
        height: auto;
    }
    .main {
        margin-left: 0;
        padding: 1.5rem;
    }
    .container {
        flex-direction: column;
    }
}