:root {
            --bg-dark: #0a0a0f;
            --bg-card: #12121a;
            --bg-code: #1a1a2e;
            --neon-cyan: #00f5ff;
            --neon-magenta: #ff00ff;
            --neon-purple: #b366ff;
            --text-primary: #ffffff;
            --text-secondary: #a0a0b0;
            --border-color: #2a2a3a;
            --success-green: #4ec9b0;
            --warning-yellow: #dcdcaa;
        }

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

        body {
            font-family: 'Space Grotesk', sans-serif;
            background: var(--bg-dark);
            color: var(--text-primary);
            line-height: 1.7;
            min-height: 100vh;
        }

        /* Grid background */
        body::before {
            content: '';
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: 
                linear-gradient(90deg, rgba(0,245,255,0.03) 1px, transparent 1px),
                linear-gradient(rgba(0,245,255,0.03) 1px, transparent 1px);
            background-size: 50px 50px;
            pointer-events: none;
            z-index: -1;
        }

        /* Header */
        .header {
            background: var(--bg-card);
            border-bottom: 1px solid var(--border-color);
            padding: 1rem 2rem;
            position: sticky;
            top: 0;
            z-index: 100;
        }

        .header-content {
            max-width: 1200px;
            margin: 0 auto;
            display: flex;
            align-items: center;
            justify-content: space-between;
            gap: 1rem;
        }

        .header-brand {
            display: flex;
            align-items: center;
            gap: 1rem;
            text-decoration: none;
            color: var(--text-primary);
        }

        .header-brand:hover {
            color: var(--neon-cyan);
        }

        .header-title {
            font-size: 1.25rem;
            font-weight: 600;
            background: linear-gradient(135deg, var(--neon-cyan), var(--neon-magenta));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }

        .header-nav {
            display: flex;
            gap: 0.5rem;
        }

        .nav-btn {
            display: inline-flex;
            align-items: center;
            gap: 0.5rem;
            padding: 0.5rem 1rem;
            background: transparent;
            border: 1px solid var(--border-color);
            border-radius: 6px;
            color: var(--text-secondary);
            text-decoration: none;
            font-size: 0.875rem;
            transition: all 0.2s ease;
            cursor: pointer;
            font-family: inherit;
        }

        .nav-btn:hover:not(:disabled) {
            border-color: var(--neon-cyan);
            color: var(--neon-cyan);
        }

        .nav-btn:disabled {
            opacity: 0.4;
            cursor: not-allowed;
        }

        /* Sidebar */
        .layout {
            display: flex;
            max-width: 1400px;
            margin: 0 auto;
        }

        .sidebar {
            width: 280px;
            background: var(--bg-card);
            border-right: 1px solid var(--border-color);
            height: calc(100vh - 65px);
            position: sticky;
            top: 65px;
            overflow-y: auto;
            flex-shrink: 0;
        }

        .sidebar-section {
            padding: 1rem;
        }

        .sidebar-title {
            font-size: 0.75rem;
            text-transform: uppercase;
            letter-spacing: 0.1em;
            color: var(--text-secondary);
            margin-bottom: 0.75rem;
            padding: 0 0.5rem;
        }

        .step-link {
            display: flex;
            align-items: center;
            gap: 0.75rem;
            padding: 0.625rem 0.75rem;
            border-radius: 6px;
            text-decoration: none;
            color: var(--text-secondary);
            font-size: 0.875rem;
            transition: all 0.2s ease;
            margin-bottom: 0.25rem;
        }

        .step-link:hover {
            background: rgba(0,245,255,0.1);
            color: var(--text-primary);
        }

        .step-link.active {
            background: linear-gradient(135deg, rgba(0,245,255,0.2), rgba(255,0,255,0.2));
            color: var(--text-primary);
            border-left: 3px solid var(--neon-cyan);
        }

        .step-number {
            width: 24px;
            height: 24px;
            display: flex;
            align-items: center;
            justify-content: center;
            background: var(--border-color);
            border-radius: 6px;
            font-size: 0.75rem;
            font-weight: 600;
            font-family: 'JetBrains Mono', monospace;
            flex-shrink: 0;
        }

        .step-link.active .step-number {
            background: linear-gradient(135deg, var(--neon-cyan), var(--neon-magenta));
            color: var(--bg-dark);
        }

        /* Main Content */
        .main {
            flex: 1;
            min-width: 0;
            padding: 2rem 3rem;
        }

        .content {
            max-width: 800px;
            margin: 0 auto;
        }

        /* Loading */
        .loading {
            display: flex;
            align-items: center;
            justify-content: center;
            height: 300px;
            color: var(--text-secondary);
        }

        .loading::after {
            content: '';
            width: 32px;
            height: 32px;
            border: 3px solid var(--border-color);
            border-top-color: var(--neon-cyan);
            border-radius: 50%;
            animation: spin 0.8s linear infinite;
            margin-left: 1rem;
        }

        @keyframes spin {
            to { transform: rotate(360deg); }
        }

        /* Markdown Styles */
        .markdown h1 {
            font-size: 2.25rem;
            font-weight: 700;
            margin-bottom: 1.5rem;
            background: linear-gradient(135deg, var(--neon-cyan), var(--neon-magenta));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
            line-height: 1.3;
        }

        .markdown h2 {
            font-size: 1.5rem;
            font-weight: 600;
            margin: 2.5rem 0 1rem;
            color: var(--neon-cyan);
            border-bottom: 1px solid var(--border-color);
            padding-bottom: 0.5rem;
        }

        .markdown h3 {
            font-size: 1.25rem;
            font-weight: 600;
            margin: 2rem 0 0.75rem;
            color: var(--neon-magenta);
        }

        .markdown h4 {
            font-size: 1.1rem;
            font-weight: 600;
            margin: 1.5rem 0 0.5rem;
            color: var(--text-primary);
        }

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

        .markdown a {
            color: var(--neon-cyan);
            text-decoration: none;
        }

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

        .markdown strong {
            color: var(--text-primary);
            font-weight: 600;
        }

        .markdown ul, .markdown ol {
            margin: 1rem 0 1.5rem 1.5rem;
            color: var(--text-secondary);
        }

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

        .markdown li::marker {
            color: var(--neon-cyan);
        }

        /* Checkboxes */
        .markdown input[type="checkbox"] {
            appearance: none;
            width: 18px;
            height: 18px;
            border: 2px solid var(--border-color);
            border-radius: 4px;
            margin-right: 0.5rem;
            vertical-align: middle;
            position: relative;
            cursor: pointer;
        }

        .markdown input[type="checkbox"]:checked {
            background: var(--neon-cyan);
            border-color: var(--neon-cyan);
        }

        .markdown input[type="checkbox"]:checked::after {
            content: '✓';
            position: absolute;
            color: var(--bg-dark);
            font-size: 12px;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
        }

        /* Code blocks */
        .markdown code {
            font-family: 'JetBrains Mono', monospace;
            font-size: 0.875em;
        }

        .markdown :not(pre) > code {
            background: var(--bg-code);
            padding: 0.2em 0.4em;
            border-radius: 4px;
            color: var(--warning-yellow);
        }

        .markdown pre {
            background: var(--bg-code);
            border: 1px solid var(--border-color);
            border-radius: 8px;
            padding: 1.25rem;
            overflow-x: auto;
            margin: 1.5rem 0;
        }

        .markdown pre code {
            color: var(--text-primary);
            background: none;
            padding: 0;
        }

        /* Blockquotes / Tips */
        .markdown blockquote {
            background: var(--bg-card);
            border-left: 4px solid var(--neon-cyan);
            border-radius: 0 8px 8px 0;
            padding: 1rem 1.25rem;
            margin: 1.5rem 0;
        }

        .markdown blockquote p {
            margin: 0;
            color: var(--text-secondary);
        }

        .markdown blockquote p:first-child {
            font-weight: 600;
            color: var(--neon-cyan);
        }

        /* Images */
        .markdown img {
            max-width: 100%;
            border-radius: 8px;
            border: 1px solid var(--border-color);
            margin: 1.5rem 0;
        }

        /* Tables */
        .markdown table {
            width: 100%;
            border-collapse: collapse;
            margin: 1.5rem 0;
        }

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

        .markdown th {
            background: var(--bg-card);
            color: var(--text-primary);
            font-weight: 600;
        }

        .markdown td {
            color: var(--text-secondary);
        }

        .markdown tr:hover td {
            background: rgba(0,245,255,0.05);
        }

        /* Horizontal rule */
        .markdown hr {
            border: none;
            border-top: 1px solid var(--border-color);
            margin: 2.5rem 0;
        }

        /* Navigation Footer */
        .nav-footer {
            display: flex;
            justify-content: space-between;
            margin-top: 3rem;
            padding-top: 2rem;
            border-top: 1px solid var(--border-color);
        }

        .nav-footer-btn {
            display: inline-flex;
            align-items: center;
            gap: 0.5rem;
            padding: 0.75rem 1.5rem;
            background: var(--bg-card);
            border: 1px solid var(--border-color);
            border-radius: 8px;
            color: var(--text-primary);
            text-decoration: none;
            font-weight: 500;
            transition: all 0.2s ease;
        }

        .nav-footer-btn:hover {
            border-color: var(--neon-cyan);
            transform: translateY(-2px);
        }

        .nav-footer-btn.disabled {
            opacity: 0.4;
            pointer-events: none;
        }

        /* Mobile */
        @media (max-width: 900px) {
            .sidebar {
                display: none;
            }
            
            .main {
                padding: 1.5rem;
            }

            .header-title {
                display: none;
            }
        }